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Molecular dynamics simulation results. (a, b) Side and top views of the homology model for the lipase QLM. The lid and catalytic domain are colored in red and gray, and the active site residue S89 is shown in a van der Waals sphere representation. (c−e) Simulation systems for the QLM on GO (c), GO/GR (d), and GR (e) nanosheets, respectively. Carbon, oxygen, and hydrogen atoms in each nanosheet are shown as cyan, red, and white spheres, respectively. Water is rendered transparently, and ions are not depicted. (f) Timedepenedent RMSDs for protein backbone atoms in different simulation systems (two independent runs for GO/GR, one each for GO and GR). The flexible N (residues 1−11) and C termini (residues 267−277) are not included in the calculations.
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Lipases, which can be immobilized and reused for many reaction cycles, are important enzymes with many industrial applications. A key challenge for in lipase immobilization for catalysis is to open the lipase lid and maintain it in an open conformation in order to expose its active site. Here we have designed “tailor-made” graphene-based nano-suppo...
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... lipase adsorption onto GO was confirmed, the effect of hydrophobicity on the immobilization process was investigated using chemically reduced GOs (CRGOs) with varying degrees of hydrophobicity/hydrophilicity, as synthesized by L-ascorbic acid (L-AA) reduction. GO and CRGO reduced for 1, 2, 3, and 4 h exhibited water contact angles of 28 ± 4, 38 ± 1, 46 ± 1, 62 ± 4, and 70.6 ± 2°, respectively. Importantly, surface adsorption often leads to changes in the secondary structure of proteins. 32 We thus employed CD spectroscopy to study the conformational changes brought about by QLM immobilization on different hydrophobic surfaces (Figure 1f), All CD spectra presented minima at 208 nm and maxima at 190 nm, indicating a general excess of α-helical content. 33 As the surface hydrophobicity within the CRGO series increases, we observe a constant decrease in ellipticity at 208 nmsuggesting an associated decrease in α-helical content 34 after immobiliza- tion. This observation implies that α-helical structures are destabilized as oxygen-containing functional groups are system- atically removed from the GO surface ( Figure S2 in the Supporting Information). Intriguingly, this spectral trend could arise from the binding of hydrophobic lipase lids to hydrophobic patches on GO scaffolds. It was previously reported that the immobilization of Burkholderia cepacia lipase (BCL) on a hydrophobic support (the microporous resin NKA) resulted in a decrease in α-helical content and a concomitant opening of the BCL active site. 35 It is thus conceivable that binding between QLM's hydrophobic lid and hydrophobic regions on GO could disrupt the lid's helical structure, a conformational change that might, in turn, significantly enhance QLM activity. MD studies (discussed in depth below) indeed support the notion that surface-induced lid opening becomes more prominent with increasing hydro- ...
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... better understand the molecular details of interactions between the lipase QLM and CRGOs, we carried out molecular dynamics (MD) simulations of QLM adsorbed onto various CRGO nanosheets. Figure 2a,b illustrates the side and top views of our atomistic QLM model. The enzyme's active site (hallmarked by Ser89) is occluded by a lipase lid containing three helices (two long and one short) that are joined by flexible connector regions. It is now well-known that the oxidized groups on the graphene oxide are far from uniform they are randomly distributed but also strongly correlated with each other through the so-called "getting together effect". This effect is mainly due to the fact that, once one of the carbon atoms in graphene is oxidized, its neighboring carbon atoms connected by π−π bonds will become unstable and hence are more prone to be oxidized. Similarly, when these neighboring carbon atoms are oxidized, they would further induce other neighboring carbon atoms to be oxidized. 41 As a result, "chunks of hydrophobic (sp 2 domain) regions and chunks of oxidized hydrophilic regions coexist on the GO", 42 resulting in numerous GO domains, graphene (GR) domains, and GO/ GR boundaries. In correspondence with these different CRGOs found in the experiment, we simulated three types of nanosheets: (1) a GO nanosheet that has the molecular formula C 10 O 2 H (highly oxidized, Figure 2c), (2) a GO/GR nanosheet wherein 50% of GO oxidation sites have been replaced by bare graphene (GR) atoms (Figure 2d), and (3) a GR nanosheet that contains no oxidization sites at all ( Figure 2e). The dynamic processes of QLM adsorption onto these nanosheets were simulated independently, as shown in Figure 2c−e. Due to the complex nature of interactions between QLM and the GO/GR nanosheet, two separate simulations (labeled as GO/GR-1 and GO/GR-2) were performed in that case. Both of these simulation runs started from the same state, wherein the QLM was initiated 5 Å above the interface between the GO and GR domains. Figure 2f shows the root-mean-square deviation (RMSD) of the QLM structure from its starting configuration. From analyses of four MD trajectories, the QLM was adsorbed onto each nanosheet within 10 ns of simulation time. After that, dynamic interactions between the QLM and nanosheets ...
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... better understand the molecular details of interactions between the lipase QLM and CRGOs, we carried out molecular dynamics (MD) simulations of QLM adsorbed onto various CRGO nanosheets. Figure 2a,b illustrates the side and top views of our atomistic QLM model. The enzyme's active site (hallmarked by Ser89) is occluded by a lipase lid containing three helices (two long and one short) that are joined by flexible connector regions. It is now well-known that the oxidized groups on the graphene oxide are far from uniform they are randomly distributed but also strongly correlated with each other through the so-called "getting together effect". This effect is mainly due to the fact that, once one of the carbon atoms in graphene is oxidized, its neighboring carbon atoms connected by π−π bonds will become unstable and hence are more prone to be oxidized. Similarly, when these neighboring carbon atoms are oxidized, they would further induce other neighboring carbon atoms to be oxidized. 41 As a result, "chunks of hydrophobic (sp 2 domain) regions and chunks of oxidized hydrophilic regions coexist on the GO", 42 resulting in numerous GO domains, graphene (GR) domains, and GO/ GR boundaries. In correspondence with these different CRGOs found in the experiment, we simulated three types of nanosheets: (1) a GO nanosheet that has the molecular formula C 10 O 2 H (highly oxidized, Figure 2c), (2) a GO/GR nanosheet wherein 50% of GO oxidation sites have been replaced by bare graphene (GR) atoms (Figure 2d), and (3) a GR nanosheet that contains no oxidization sites at all ( Figure 2e). The dynamic processes of QLM adsorption onto these nanosheets were simulated independently, as shown in Figure 2c−e. Due to the complex nature of interactions between QLM and the GO/GR nanosheet, two separate simulations (labeled as GO/GR-1 and GO/GR-2) were performed in that case. Both of these simulation runs started from the same state, wherein the QLM was initiated 5 Å above the interface between the GO and GR domains. Figure 2f shows the root-mean-square deviation (RMSD) of the QLM structure from its starting configuration. From analyses of four MD trajectories, the QLM was adsorbed onto each nanosheet within 10 ns of simulation time. After that, dynamic interactions between the QLM and nanosheets ...
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... better understand the molecular details of interactions between the lipase QLM and CRGOs, we carried out molecular dynamics (MD) simulations of QLM adsorbed onto various CRGO nanosheets. Figure 2a,b illustrates the side and top views of our atomistic QLM model. The enzyme's active site (hallmarked by Ser89) is occluded by a lipase lid containing three helices (two long and one short) that are joined by flexible connector regions. It is now well-known that the oxidized groups on the graphene oxide are far from uniform they are randomly distributed but also strongly correlated with each other through the so-called "getting together effect". This effect is mainly due to the fact that, once one of the carbon atoms in graphene is oxidized, its neighboring carbon atoms connected by π−π bonds will become unstable and hence are more prone to be oxidized. Similarly, when these neighboring carbon atoms are oxidized, they would further induce other neighboring carbon atoms to be oxidized. 41 As a result, "chunks of hydrophobic (sp 2 domain) regions and chunks of oxidized hydrophilic regions coexist on the GO", 42 resulting in numerous GO domains, graphene (GR) domains, and GO/ GR boundaries. In correspondence with these different CRGOs found in the experiment, we simulated three types of nanosheets: (1) a GO nanosheet that has the molecular formula C 10 O 2 H (highly oxidized, Figure 2c), (2) a GO/GR nanosheet wherein 50% of GO oxidation sites have been replaced by bare graphene (GR) atoms (Figure 2d), and (3) a GR nanosheet that contains no oxidization sites at all ( Figure 2e). The dynamic processes of QLM adsorption onto these nanosheets were simulated independently, as shown in Figure 2c−e. Due to the complex nature of interactions between QLM and the GO/GR nanosheet, two separate simulations (labeled as GO/GR-1 and GO/GR-2) were performed in that case. Both of these simulation runs started from the same state, wherein the QLM was initiated 5 Å above the interface between the GO and GR domains. Figure 2f shows the root-mean-square deviation (RMSD) of the QLM structure from its starting configuration. From analyses of four MD trajectories, the QLM was adsorbed onto each nanosheet within 10 ns of simulation time. After that, dynamic interactions between the QLM and nanosheets ...
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... better understand the molecular details of interactions between the lipase QLM and CRGOs, we carried out molecular dynamics (MD) simulations of QLM adsorbed onto various CRGO nanosheets. Figure 2a,b illustrates the side and top views of our atomistic QLM model. The enzyme's active site (hallmarked by Ser89) is occluded by a lipase lid containing three helices (two long and one short) that are joined by flexible connector regions. It is now well-known that the oxidized groups on the graphene oxide are far from uniform they are randomly distributed but also strongly correlated with each other through the so-called "getting together effect". This effect is mainly due to the fact that, once one of the carbon atoms in graphene is oxidized, its neighboring carbon atoms connected by π−π bonds will become unstable and hence are more prone to be oxidized. Similarly, when these neighboring carbon atoms are oxidized, they would further induce other neighboring carbon atoms to be oxidized. 41 As a result, "chunks of hydrophobic (sp 2 domain) regions and chunks of oxidized hydrophilic regions coexist on the GO", 42 resulting in numerous GO domains, graphene (GR) domains, and GO/ GR boundaries. In correspondence with these different CRGOs found in the experiment, we simulated three types of nanosheets: (1) a GO nanosheet that has the molecular formula C 10 O 2 H (highly oxidized, Figure 2c), (2) a GO/GR nanosheet wherein 50% of GO oxidation sites have been replaced by bare graphene (GR) atoms (Figure 2d), and (3) a GR nanosheet that contains no oxidization sites at all ( Figure 2e). The dynamic processes of QLM adsorption onto these nanosheets were simulated independently, as shown in Figure 2c−e. Due to the complex nature of interactions between QLM and the GO/GR nanosheet, two separate simulations (labeled as GO/GR-1 and GO/GR-2) were performed in that case. Both of these simulation runs started from the same state, wherein the QLM was initiated 5 Å above the interface between the GO and GR domains. Figure 2f shows the root-mean-square deviation (RMSD) of the QLM structure from its starting configuration. From analyses of four MD trajectories, the QLM was adsorbed onto each nanosheet within 10 ns of simulation time. After that, dynamic interactions between the QLM and nanosheets ...
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... better understand the molecular details of interactions between the lipase QLM and CRGOs, we carried out molecular dynamics (MD) simulations of QLM adsorbed onto various CRGO nanosheets. Figure 2a,b illustrates the side and top views of our atomistic QLM model. The enzyme's active site (hallmarked by Ser89) is occluded by a lipase lid containing three helices (two long and one short) that are joined by flexible connector regions. It is now well-known that the oxidized groups on the graphene oxide are far from uniform they are randomly distributed but also strongly correlated with each other through the so-called "getting together effect". This effect is mainly due to the fact that, once one of the carbon atoms in graphene is oxidized, its neighboring carbon atoms connected by π−π bonds will become unstable and hence are more prone to be oxidized. Similarly, when these neighboring carbon atoms are oxidized, they would further induce other neighboring carbon atoms to be oxidized. 41 As a result, "chunks of hydrophobic (sp 2 domain) regions and chunks of oxidized hydrophilic regions coexist on the GO", 42 resulting in numerous GO domains, graphene (GR) domains, and GO/ GR boundaries. In correspondence with these different CRGOs found in the experiment, we simulated three types of nanosheets: (1) a GO nanosheet that has the molecular formula C 10 O 2 H (highly oxidized, Figure 2c), (2) a GO/GR nanosheet wherein 50% of GO oxidation sites have been replaced by bare graphene (GR) atoms (Figure 2d), and (3) a GR nanosheet that contains no oxidization sites at all ( Figure 2e). The dynamic processes of QLM adsorption onto these nanosheets were simulated independently, as shown in Figure 2c−e. Due to the complex nature of interactions between QLM and the GO/GR nanosheet, two separate simulations (labeled as GO/GR-1 and GO/GR-2) were performed in that case. Both of these simulation runs started from the same state, wherein the QLM was initiated 5 Å above the interface between the GO and GR domains. Figure 2f shows the root-mean-square deviation (RMSD) of the QLM structure from its starting configuration. From analyses of four MD trajectories, the QLM was adsorbed onto each nanosheet within 10 ns of simulation time. After that, dynamic interactions between the QLM and nanosheets ...
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... better understand the molecular details of interactions between the lipase QLM and CRGOs, we carried out molecular dynamics (MD) simulations of QLM adsorbed onto various CRGO nanosheets. Figure 2a,b illustrates the side and top views of our atomistic QLM model. The enzyme's active site (hallmarked by Ser89) is occluded by a lipase lid containing three helices (two long and one short) that are joined by flexible connector regions. It is now well-known that the oxidized groups on the graphene oxide are far from uniform they are randomly distributed but also strongly correlated with each other through the so-called "getting together effect". This effect is mainly due to the fact that, once one of the carbon atoms in graphene is oxidized, its neighboring carbon atoms connected by π−π bonds will become unstable and hence are more prone to be oxidized. Similarly, when these neighboring carbon atoms are oxidized, they would further induce other neighboring carbon atoms to be oxidized. 41 As a result, "chunks of hydrophobic (sp 2 domain) regions and chunks of oxidized hydrophilic regions coexist on the GO", 42 resulting in numerous GO domains, graphene (GR) domains, and GO/ GR boundaries. In correspondence with these different CRGOs found in the experiment, we simulated three types of nanosheets: (1) a GO nanosheet that has the molecular formula C 10 O 2 H (highly oxidized, Figure 2c), (2) a GO/GR nanosheet wherein 50% of GO oxidation sites have been replaced by bare graphene (GR) atoms (Figure 2d), and (3) a GR nanosheet that contains no oxidization sites at all ( Figure 2e). The dynamic processes of QLM adsorption onto these nanosheets were simulated independently, as shown in Figure 2c−e. Due to the complex nature of interactions between QLM and the GO/GR nanosheet, two separate simulations (labeled as GO/GR-1 and GO/GR-2) were performed in that case. Both of these simulation runs started from the same state, wherein the QLM was initiated 5 Å above the interface between the GO and GR domains. Figure 2f shows the root-mean-square deviation (RMSD) of the QLM structure from its starting configuration. From analyses of four MD trajectories, the QLM was adsorbed onto each nanosheet within 10 ns of simulation time. After that, dynamic interactions between the QLM and nanosheets ...
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... better comprehend the decrease in enzymatic activity associated with high levels of hydrophobicity, we tracked the hydrophobic QLM residues most involved in interactions with the GR nanosheet in MD simulations ( Figure S5 in the Supporting Information). Though strong hydrophobic contacts prevent QLM desorption from the GR nanosheet surface, its lateral diffusion across the nanosheet is marked (see Figure S6 in the Supporting Information). Thus, it is likely that adsorbed QLMs could encounter one another and aggregate on a bare GR surface, mutually occluding their active sites and thus reducing catalytic activity (Figure 2). Our GO/GR simulations suggest that such diffusion is effectively arrested by the presence of oxidation sites on the GR surface. As noted previously, exceptionally strong hydrophobic interactions with pristine graphene might also cause partial QLM unfolding, as seen in previous studies on the protein HP35 47 and as supported by our spectroscopic data. Some combination of these factors, perhaps, explains why enzymatic activity is disturbed once the hydrophobicity of GO surpasses a certain limit. Previous experiments have shown that hydrophobic mesoporous octyl silica can denature Cal B through overly strong hydrophobic adsorption; 48 other enzymes (such as α- ChT) have exhibited depressed catalytic activity due to exceptionally strong interactions with their supports, as well. 49 By analyzing the interaction energies, including van der Waals and electrostatic energy components, between the lipase and the various nanosheets simulated here, we find that equilibrated energies are more negative when the interactions are more hydrophobic (Figure 3f). For the QLM adsorbed onto the GR nanosheet, the total protein−GR interaction energy reached around −440 kcal/mol, more than 4 times that seen with the weakly interacting GO. Further rearrangement of auxiliary hydrophobic residues in the direction of the GR surface (a process that could lead to denaturation) may occur on experimental time scales. When hydrophobic interactions become more prominent, the absolute interaction energy between the QLM and the GO/GR nanosheet also becomes more ...
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Biographene was successfully produced in water from graphite flakes by a simple, rapid, and efficient methodology based on a bioexfoliation technology. The methodology consisted in the application of a lipase, with a unique mechanism of interaction with hydrophobic surfaces, combined with a previous mechanical sonication, to selectively generate li...
Citations
... The adsorption could change the enzyme to a state with an opened catalytic cavity, even in the absence of direct interaction of the active site with the GO [29,30]. GO can induce changes in the tertiary structure of lipase while maintaining the secondary structure increasing its activity, but our graphene oxide has not been partially reduced to increase the hydrophobicity and only a minor activation could be expected from GO [31,32]. Lipases from Thermomyces lanuginosa and Alcaligenes sp. ...
Obesity is a global pandemic, thus novel developments that reduce the absorption of fats is of interest. We have evaluated the effect of graphene oxide (GO) on the lipase catalyzed hydrolysis of fats (tributyrin, sunflower and olive oil) under simulated duodenal conditions. Results indicate that the presence of GO in the digestion mixture can inhibit lipase activity up to a 90% of the initial reaction rate, and this inhibition lasts even during 2 h of digestion. The inhibition mechanism seems non competitive and could be opposite to the effect of bile salts, although the direct interaction between GO and the enzyme cannot be discarded. The inhibition is found also in alimentary fats suggesting that GO could be a strong inhibitor for fat hydrolysis.
... Commonly used immobilized methods include adsorption, entrapment, cross-linking, and covalent binding, which can maintain the catalytic activity of enzymes and improve their stability or resistance to inhibitors and chemical reagents (Dong et al., 2012;Liang et al., 2015;Zhao et al., 2017). Moreover, due to the great flexibility of the active center of lipases, the activity, selectivity, or specificity of lipases are easily adjusted during immobilization (dos Santos et al., 2015;Mathesh et al., 2016;Stepankova et al., 2013). While the stability of immobilized enzymes can be improved by sacrificing enzymatic activity, simultaneously achieving high retention of enzyme activity and enhanced stability, as well as reusability, remains a considerable challenge for immobilized enzyme systems. ...
... Modifying the surface of magnetic nanoparticle carriers with ILs would improve the electrostatic interaction, hydrophobic interaction, and hydrogen bond between the carriers and the lipase, efficiently preventing the leakage of lipase (Qin et al. 2016). The introduction of ILs increases hydrophobic interaction between the carriers and the lipase, leading to the opening of the lipase lid and making its active site more accessible, and the activity of the lipase is enhanced as a result of interface activation (Brzozowski et al. 1991;Mathesh et al. 2016;Wang et al. 2021b). Moreover, the enhancement of the activity of lipase immobilization by ILs may also be attributed to the increase in the rigidity of the lipase structure (Jiang et al. 2009). ...
Enzyme immobilized on magnetic nanomaterials is a promising biocatalyst with efficient recovery under applied magnets. In this study, a recombinant extracellular lipase from Aspergillus niger GZUF36 (PEXANL1) expressed in Pichia pastoris GS115 was immobilized on ionic liquid-modified magnetic nano ferric oxide (Fe3O4@SiO2@ILs) via electrostatic and hydrophobic interaction. The morphology, structure, and properties of Fe3O4@SiO2@ILs and immobilized PEXANL1 were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction, vibration sample magnetometer, and zeta potential analysis. Under optimized conditions, the immobilization efficiency and activity recovery of immobilized PEXANL1 were 52 ± 2% and 122 ± 2%, respectively. The enzymatic properties of immobilized PEXANL1 were also investigated. The results showed that immobilized PEXANL1 achieved the maximum activity at pH 5.0 and 45 °C, and the lipolytic activity of immobilized PEXANL1 was more than twice that of PEXANL1. Compared to PEXANL1, immobilized PEXANL1 exhibited enhanced tolerance to temperature, metal ions, surfactants, and organic solvents. The operation stability experiments revealed that immobilized PEXANL1 maintained 86 ± 3% of its activity after 6 reaction cycles. The enhanced catalytic performance in enzyme immobilization on Fe3O4@SiO2@ILs made nanobiocatalysts a compelling choice for bio-industrial applications. Furthermore, Fe3O4@SiO2@ILs could also benefit various industrial enzymes and their practical uses.
Key points
• Immobilized PEXANL1 was confirmed by SEM, FT-IR, and XRD.
• The specific activity of immobilized PEXANL1 was more than twice that of PEXANL1.
• Immobilized PEXANL1 had improved properties with good operational stability.
Graphical abstract
... Thus, enzymes with robust stability profiles, such as those that can retain their activity under extreme pH, temperature, salinity, heavy metals, solvents, and inhibitors, may be needed for the remediation and valorization of most waste. Unfortunately, very few enzymes have some or a combination of these properties (Olusesan et al., 2011;Mathesh et al., 2016;Akanbi et al., 2020). So, waste may have to be pretreated before enzymatic treatment, which can add to the cost of generating value out of the waste. ...
... Besides, the electrostatic potential energy distribution analysis of ChryBHE-Tase, especially at the substrate binding cleft (SBC, Fig. 2g [13][14][15][16][17]. Almost no BHET molecule could be detected in the SBC of BsEst and ChryBHE-Tase (Fig. 2i). However, a certain number of water molecules were present in SBC, indicating the larger BHET might be blocked by uncertain barrier structures (the particular region is called lid in hydrolase [56][57][58] ). These results were confirmed by the spatial distribution function (SDF) of BHET and water around the protein surface (Fig. 3b). ...
... 11 and 12). We found that the truncated barrier in BsEst and ChryBHETase has low flexibility (Fig. 2h, Supplementary Fig. 21, and 25 RMSF: 1~3 Å), which is different from the flexible lid in lipase that distinguishes barrier engineering from lid engineering 57,58,60,61 . The rigid barrier is not favorable for the access of substrate into SBC. ...
Although considerable research achievements have been made to address the plastic crisis using enzymes, their applications are limited due to incomplete degradation and low efficiency. Herein, we report the identification and subsequent engineering of BHETases, which have the potential to improve the efficiency of PET recycling and upcycling. Two BHETases (ChryBHETase and BsEst) are identified from the environment via enzyme mining. Subsequently, mechanism-guided barrier engineering is employed to yield two robust and thermostable ΔBHETases with up to 3.5-fold enhanced kcat/KM than wild-type, followed by atomic resolution understanding. Coupling ΔBHETase into a two-enzyme system overcomes the challenge of heterogeneous product formation and results in up to 7.0-fold improved TPA production than seven state-of-the-art PET hydrolases, under the conditions used here. Finally, we employ a ΔBHETase-joined tandem chemical-enzymatic approach to valorize 21 commercial post-consumed plastics into virgin PET and an example chemical (p-phthaloyl chloride) for achieving the closed-loop PET recycling and open-loop PET upcycling.
... This can be achieved and tuned through chemical reduction of GO, which allows modulating the enzyme activity. MD simulations were used to study the molecular mechanisms driving the lid-opening, shedding light on the key role of the hydrophobic interactions occurring between the interface of the lipase and GO (Mathesh et al., 2016). Additionally, Zhuang et al. (2020) observed that the lipase immobilized on functionalized GO is around 20 times more active than when immobilized on GO. ...
In recent years, simulations have been used to great advantage to understand the structural and dynamic aspects of distinct enzyme immobilization strategies, as experimental techniques have limitations in establishing their impact at the molecular level. In this review, we discuss how molecular dynamic simulations have been employed to characterize the surface phenomenon in the enzyme immobilization procedure, in an attempt to decipher its impact on the enzyme features, such as activity and stability. In particular, computational studies on the immobilization of enzymes using i) nanoparticles, ii) self-assembled monolayers, iii) graphene and carbon nanotubes, and iv) other surfaces are covered. Importantly, this thorough literature survey reveals that, while simulations have been primarily performed to rationalize the molecular aspects of the immobilization event, their use to predict adequate protocols that can control its impact on the enzyme properties is, up to date, mostly missing.
... [15][16][17][18][19] Bile salts can induce the activation of lipase at the interface, thus promoting the chiral catalytic ability of a lipase. 10,[19][20][21][22][23] Bile acid plays an important role in the field of molecular recognition. The recognition principle stems from the chiral rigid structure of the bile acid. ...
BACKGROUND
Lipase as a hydrolase has important applications in the synthesis of chiral drugs. Based on the special interfacial activity of lipase, bile salt as a biosurfactant can effectively improve the catalytic activity of lipase.
RESULTS
In this work, the strong selective recognition of the molecular tweezers and guest molecules helps improve the guest molecule concentration near the lipase catalytic center. However, this strong recognition will also make it difficult for the guest molecules to break away from the molecular tweezers. Therefore, there is an optimal value for this recognition that can effectively improve the chiral resolution effect of lipase.
CONCLUSIONS
The two hydroxyl groups on deoxycholic acid were modified to prepare deoxycholic acid‐based molecular tweezers with two ‘arms’ and one ‘crack.’ The recognition performance between the molecular tweezers and amino acid methyl ester was determined by UV spectrophotometry. According to the binding constant, Ka, and free energy, −ΔG0, a complex formed between the deoxycholic acid‐based molecular tweezers (host) and amino acid methyl ester (guest) due to chiral recognition. Molecular tweezers were subsequently mixed with porcine pancreatic lipase (PPL) and candida rugosa lipase (CRL), respectively, to catalyze the transesterification of racemic tryptophan methyl ester. © 2023 Society of Chemical Industry.
... Lipase from the Alcaligenes sp. (adsorption), [233] Lipase from ...
Lipase has been used extensively in the industrial sector for edible fats and oils processing. However, its industrial scale application is often hampered by limitations such as low stability and poor reusability. A countermeasure taken is lipase immobilization which is a technique to confine enzyme molecules within a fixed space while maintaining catalytic activity. This usually enhances lipase stability and allows its reusability together with other advantages like simple product separation and better design options for the bioreactor. Meanwhile, lipase immobilization often involves high cost and thus making them less attractive for certain industrial applications (e.g., monoglyceride and diglyceride production, vitamin C esters synthesis) compared to chemical catalysts. Their lower activity compared to free lipase and chemical catalysts is also a challenge that needs to be overcome. Therefore, this paper will discuss the important characteristics of lipase, trending materials and protocols used in lipase immobilization, and current applications of immobilized lipase in edible oil and fat industries. This is to provide a thorough understanding of lipase immobilization technology in edible oil and fat modifications so that the strategy for its application can be more appropriately designed for optimized industrial benefits.
... While further investigation is needed, we posit that the relatively polar (compared to PEG) PSar polyamide may prevent the helical lid of palatase 20000L from opening, an important step in lipase-catalyzed reactions which benefit from a more hydrophobic environment. 68 Three-Step, One-Pot Chemoenzymatic Sequence. As the toolbox of established reactions that can now be run in the same aqueous reaction medium continues to expand, so do opportunities to telescope reactions that can now be run in a single pot without reliance on wasteful intermediate workup and purification steps. ...
Savie is a biodegradable surfactant derived from vitamin E and polysarcosine (PSar) developed for use in organic synthesis in recyclable water. This includes homogeneous catalysis (including examples employing only ppm levels of catalyst), heterogeneous catalysis, and biocatalytic transformations, including a multistep chemoenzymatic sequence. Use of Savie frequently leads to significantly higher yields than do conventional surfactants, while obviating the need for waste-generating organic solvents.
... These abundant functional groups on the graphene oxide surface can be key chemical structures used as immobilization sites for lipases. The immobilization process is effectively facilitated by chemical bonds and electrostatic interactions [55,56]. Considering these features, the bonding of magnetic nanoparticles on the surface of graphene oxide provides magnetic properties with a high specific surface area for lipase immobilization to provide easy separation of the solids from the liquid medium [57]. ...
Candida rugosa lipase was immobilized on graphene oxides magnetized with NiFe2O4 nanoparticles (NiFe2O4-GO) and used for the transesterification of algal lipids. The VSM, FE-SEM, EDS, and FTIR analyses were done to investigate the features of nanoparticles, graphene oxide, and synthesized magnetic nanobiocatalyst. These tests confirmed the successful immobilization of Candida rugosa lipase on the base. Immobilization was caused via interfacial activation on hydrophobic supports. The lipase immobilization process was studied using different enzyme concentrations (30-160 µg/ml) at different incubation times (1-5 h). It was found that 100 µg/ml enzyme concentration (3.3 mg supports/ml solution) for 2 h incubation time were the best conditions which led to the immobilization efficiency of 78%. The results revealed that in comparison to the free enzyme, the immobilized enzyme is more thermal and pH resistant; it could retain 70% of its initial activity at 60 °C and lose only 20% at pH 9. Immobilized lipase retained 47% of its initial activity after 6 cycles of hydrolysis at 37°C and pH 7, demonstrating its reusability and resistance. Biodiesel production efficiency was obtained 80% and 68% when using free and immobilized lipase as biocatalysts, respectively.
