Fig 7 - uploaded by Edwin Moran
Content may be subject to copyright.
Representation of the villus vascular system emphasizing arteriole and venule locations. One arteriole from the mucosa directly ascends to the villus apex with oxygen then venules subsequently carry absorbed nutrients to the base. Nutrients and other information about the lumen are conveyed via vascular contents to enable accommodation by developing cells to expected conditions. Another arteriole communicates with crypt about body information and cell needs for of the villus before returning to form a confluence with descending venules from the villus and portal entry. (Adapted and redrawn from Aharinejad et al., 1991; Courtesy of Scanning Electron Microscopy Inc.).
Source publication
Recovery of dietary protein proceeds through two phases of digestion before suitable forms exist for absorption. The first phase engages the gastric system where low pH weakens overall structures allowing pepsin to disrupt hydrophobic bonding and enhance aqueous compatibility. Secondly, trypsin, chymotrypsin and elastase proteolysis in conjunction...
Context in source publication
Context 1
... microvessels accomplish many objectives: supply oxygen, remove absorbed nutrients, and provide logistical sup- port for all facets of epithelial operation (Fig. 7). Arterioles in the submucosa divide with a branch directly accessing and devoted to the crypt while another ascends to the villus apex ( Kumoro and Hashimoto, 1990;Aharinejad et al., 1991). Once at the apex, a multitude of venules subsequently cascade down the villus immediately adjacent to mature, developing, and eventually ...
Citations
... This low degree of free amino groups during the gastric stage, followed by a significant increase post-intestinal digestion was expected, since pepsin is an endopeptidase estimated to be responsible for the digestion of only ~15% of dietary protein (Smith and Morton 2010). It has previously been shown that pepsin has a preparatory function important for the subsequent trypsin and chymotrypsin-catalyzed hydrolysis in the small intestine, which the results of this work also suggested (Moran 2016;Rivera Del Rio et al., 2021). In this study only the endpoint of intestinal digestion was investigated. ...
The aim of this work was to investigate the impact of the addition of salivary α-amylase on starch hydrolysis in protein-containing dispersions during an in vitro digestion process. In vitro digestion provides useful insights on the fate of nutrients during gastro-intestinal transit in complex food matrices, an important aspect to consider when developing highly nutritious foods. Many foods contain polysaccharides, and as their disruption in the gastric stage is limited, salivary α-amylase is often neglected in in vitro studies. A reference study on the effect of salivary α-amylase using one of the most advanced and complex in vitro digestion models (INFOGEST) is, however, not available. Hence, this work reports the gastrointestinal breakdown of three mixed dispersions containing whey protein isolate with different polysaccharides: potato starch, pectin from citrus peel and maize starch. The latter was also studied after heating. No polysaccharide or salivary α-amylase-dependent effect on protein digestion was found, based on the free NH2 and SDS-PAGE. However, in the heat-treated samples, the addition of salivary α-amylase showed a significantly higher starch hydrolysis compared to the sample without α-amylase, due to the gelatinization of the starch granules, which improved the accessibility of the starch molecules to the enzyme. This work demonstrated that the presence of different types of polysaccharides does not affect protein digestion, but also it emphasizes the importance of considering the influence of processing on food structure and its digestibility, even in the simplest model systems.
... They work together with chymotrypsin and carboxypeptidase in the metabolic processing of protein hydrolysis into easily absorbed essential peptides and amino acids. These amino acids have several functions in the body, such as muscle growth and hormone production [4,5]. ...
Although enzymes have been used for thousands of years, their application in industrial processes has gained importance since the 20th century due to technological and scientific advances in several areas, including biochemistry [...]
... The hydrolyzed purslane notably increased the quantity of soluble protein, as depicted in Figure 6. Soluble proteins are either oligopeptides or amino acids that can be readily taken up by the digestive system [28]. Throughout the hydrolysis process, the interplay between the enzyme and substrate streamlined the peptide bonds, ultimately enhancing the solubility of proteins. ...
Feed ingredients such as fishmeal and soybean meal are common used in the aquaculture industry. However, they have drawbacks both environmentally and economically and should switch over to more sustainable materials. Using a weed in fish feed opens up potential and environmentally conscious possibilities. The objective of this study is to explore the potential valorization of a common weed plant called Portulaca oleracea L., using enzymatic hydrolysis for incorporation into fish feeds. This common weed can thrive by itself without human intervention. The nutrient content of P. oleracea L. was 16.33% protein, 0.88% lipid, 10.19 % ash, 26.20% crude fiber, and 46.40% carbohydrates (by differences) (% dry weight). However, the high crude fiber restricts its utilization in feed formulation. Hydrolysis has been employed to reduce crude fiber and enhance its quality. The treatments in doses are as follows: 10%, 20%, 30%. and 40% (v/w). Each treatment was conducted in three triplicates for 60 hours, 55oC, and pH 5.0. The result revealed that the nutrient quality of P. oleracea L. was improved. In conclusion, the valorized P. oleracea L. is feasible to be an ingredient in fish feed.
... According to Zhang et al. [7], in the food industry, trypsin is applied in the preparation of nutritional proteins/peptides, used in baby food to reduce your allergenicity and enhance the digestibility, and in the synthesis of protein hydrolysates [8]. However, it stands out for laboratory-scale use in protein fragmentation for further identification and characterization [1,9]. ...
This study aimed to immobilize trypsin on activated carbon submitted to different surface modifications and its application in casein hydrolysis. With the aim of determining which support can promote better maintenance of the immobilized enzyme. Results showed that pH 5.0 was obtained as optimal for immobilization and pH 9.0 for the casein hydrolysis reaction for activated carbon and glutaraldehyde functionalized carbon. Among the supports used, activated carbon modified with iron ions in the presence of a chelating agent was the one that showed best results, under the conditions evaluated in this study. Presenting an immobilization yield of 95.15% and a hydrolytic activity of 4.11 U, same as soluble enzyme (3.76 U). This derivative kept its activity stable at temperatures above 40 °C for1 h and when stored for 30 days at 5 °C. Furthermore, it was effective for more than 6 reuse cycles (under the same conditions as the 1st cycle). In general, immobilization of trypsin on metallized activated carbon can be an alternative to biocatalysis, highlighting the advantages of protease immobilization.
... Proteases are enzymes that hydrolyse proteins to polypeptides and free amino acids, which are more suitable forms for absorption by host enterocytes (Moran, 2016). Within animal production, initial interest in supplementing non-ruminant diets with exogenous proteases, typically of microbial (bacterial and fungal) origin, sought to target proteinaceous antinutrients and/or immunogenic components of the diet, such as trypsin inhibitors, to improve growth performance (Cowieson and Roos, 2016). ...
... So many of the key components secreted by the host to help manage interactions with their associated microbiome are proteinaceous in nature, including antimicrobial peptides, acute phase proteins, chemokines, cytokines, mucins, secretory IgA, tight junction proteins, whereby increased expression would enhance the requirement for constituent amino acids. For example, arginine (nitric oxide) and cystine, glutamine, glycine-serine, proline, and threonine (mucins) are amongst the best considered in the context of gastrointestinal physiology (Moran, 2016). Nitric oxide can be produced in large quantities by immune cells, particularly activated macrophages, from arginine by inducible nitric oxide synthases (Bogdan, 2001). ...
Exogenous proteases are well established for hydrolysing proteins and improving the digestibility of amino acids, which, in animal production, enhances growth performance and diet formulation flexibility. Attention has now turned to the wider, or ‘extra-proteinaceous’, benefits of proteases. Both host and (gut) microbiome utilise amino acids for diverse functions beyond just cellular growth and proliferation. For example, the host produces a diverse array of proteinaceous secretions that seek to modulate the activity of the intestinal microbiome and opportunities to interact with host (e.g., epithelial) receptors. Reciprocally, the microbiome utilises various protein-based components to perform individual lifestyle traits, such as colonising gut niches, production of virulence traits, etc., which can be influenced by protease activity and amino acid availability. In addition, microbial fermentation of proteins and amino acids produces metabolites that may be considered undesirable (e.g., toxic) for the host’s cells or, for example, can act as signalling molecules, shaping the secretion of gut hormones and function. Parallels may also exist between various antibiotic growth promoters and proteases, in that both can target/impact microbial proteins (synthesis and degradation, respectively). There are many aspects to consider, such as determining optimal intestinal levels and spectra of proteolytic activity under various scenarios, but great potential exists.
... The protein digestive process is initiated in the proventriculus of poultry where pepsin and HCl secretions split proteins into polypeptides. Several pancreatic enzymes (trypsin, chymotrypsin, carboxypeptidase, elastase) are released into the duodenum to convert polypeptides into short peptide fragments, which are, in turn, converted to di-and tripeptides (or oligopeptides) by amino peptidase and dipeptidase in the apical membrane of enterocytes (Moran 2016). Intestinal uptakes of oligopeptides are conducted via the Pept-1 transporter (Zwarycz and Wong 2013) in combination with the Na + /H + exchanger, NHE (Thwaites et al. 2002). ...
The purpose of the review is to reappraise amino acids in broilerchicken nutrition so that the chicken-meat industry may be betterplaced to enhance the utilisation of protein and amino acids bybroiler chickens. The quest to develop reduced-crude protein dietsemphasises the dichotomy between protein-bound and non-protein-bound (synthetic, crystalline) amino acids with respect todigestive dynamics. The successful development and adoption ofreduced-crude protein diets will almost certainly demand a superiorknowledge of amino acids in broiler chicken nutrition than is pre-sently the case. Consequently, there is a need to identify the short-falls in our comprehension so that they may be corrected. Theintestinal uptakes of amino acids and their transition across enter-ocytes along the small intestine to enter the portal circulation is anarea that is poorly understood. Similarly, this applies to proteinturnover and the post-enteral metabolism and partitioning ofamino acids into protein body segments. Feathering demandsabout 10% of dietary amino acids in broiler chickens, but theamino acid profile of feathers is radically different to that of skeletalmuscle. The likelihood is that more attention should be paid to theamino acid requirements of feathering, more so when birds areoffered reduced-crude protein diets because there is the possibilitythat preference is given to partitioning of amino acids for feather-ing. Reduced-crude protein diets hold several potential advantagesincluding reduced nitrogen and ammonia emissions anda decreased dependence on soybean meal as a major source ofprotein. Hence, the need for a better comprehension of amino acids in broiler chicken nutrition.
... The second layer or unstirred water layer (USWL) is formed by the collaboration of enterocytes with goblet cells that create a completely separate mucin barrier. By having a distinct internal structure, the entry of microbes from within the loose layer is restricted while simultaneously limiting the size of nutrient forms that can pass through for absorption (Corfield, 2015;Johansson et al., 2008;Moran, 2016). Preferential use of amino acids by microbes within the lumen not only minimizes their potential absorption and villus use, but a separate modified and limited large intestinal vascular system within the mucosa further discourages access from body sources (Ahmadinejad et al., 1991;Wille and Schenk, 1997). ...
... Mucin also functions as a localized buffer that optimizes the terms for final enzyme digestion and active transport while small molecular neutralizations enable direct membrane transfer (Moran, 2016). Protein digestion by pepsin and the array of subsequent pancreatic enzymes generally leads to the release of free essential amino acids while the non-essentials largely appear as peptides. ...
Endogenous protein leaving the ileum largely consists of accrued mucins from the upper gastrointestinal tract (GIT) that had resisted digestion. The amounts released rely on their mucosal generation during enteral feeding which vary with age as well as diet. These digestion resistant proteins of endogenous origin continue to be unavailable in the large intestine, whereas those of dietary origin provide amino acids that largely support the existing microbial population while denying limited amounts for absorption. Other mucins pre-exist within the large intestine as two layers at the lumen surface. A loose layer harboring a diverse microbial population is superimposed on the unstirred water layer (USWL) which simultaneously acts as an obstacle to microbes at the loose layer while performing as a molecular sieve for nutrients. The USWL is formed through interplay between enterocyte and goblet cells; however, the basis for presence of the loose layer is elusive. Large intestinal fermentation predominates within the colon of swine, whereas fowl employ their ceca. Motility within the colon of swine segregates fine materials into haustrae out-pocketings that parallel their placement within the ceca of fowl. Viscous mucins from small intestinal endogenous losses may envelop microbes within the large intestinal lumen to present successive adherents on the USWL that assemble its loose layer. The loose layer continually functions as a microbial reservoir in support of lumen fermentation. Microbial catabolism of mucin within the loose layer is known to be slow, but its proximity to the enterocyte is of advantage to enterocyte absorption with by-product amino acids fostering the USWL.
... Previous reports indicated that dietary changes are influential in modifying epithelial mucin predominantly in the small intestine (Sharma et al., 1997;Sharma and Schumacher, 2001). Goblet cells depend heavily on absorbed glutamine and glucose to synthesize mucins, which can be readily provided by prolamines and starch in grain (Moran Jr, 2016). It has been shown that feeding carbohydrates to the late-term embryo of broiler chickens can be seen to enhance mucin-2 expression and goblet cell development (Sharma et al., 1997;Smirnov et al., 2006). ...
This study explored the variation of ileal endogenous amino acid (IEAA) losses and its influencing factors in chickens offered nitrogen-free diets (NFD) containing different ratios of amylose to amylopectin (AM/AP). A total of 252 broiler chickens at 28 d old were randomly allocated into 7 treatment groups for a 3-d trial. The dietary treatments included a basal diet (control), a NFD containing corn starch (CS), and 5 NFD with AM/AP ratios of 0.20, 0.40, 0.60, 0.80, and 1.00, respectively. As the AM/AP ratio increased, the IEAA losses of all AAs, starch digestibility and maltase activity linearly decreased (P < 0.05), but the DM digestibility linearly and quadratically decreased (P < 0.05). Compared with the control, the NFD increased the number of goblet cells and its regulatory genes mucin-2 and krüppel-like factor 4 (KLF-4) while decreasing serum glucagon and thyroxine concentrations, ileal villus height, and crypt depth (P < 0.05). Additionally, NFD with lower AM/AP ratios (0.20 and 0.40) decreased the ileal microbiota species richness (P < 0.05). In all NFD groups, the number of Proteobacteria increased whereas the abundance of Firmicutes dropped (P < 0.05). However, the broilers in the AM/AP 0.60 group were closer to the digestive physiological state of chickens fed the control diet, with no significant change in maltase activity and mucin-2 expression (P < 0.05). In conclusion, increasing AM/AP ratio in a NFD decreased the IEAA losses and the apparent ileal digestibility of starch but inevitably resulted in malnutrition and disruption of gut microbiota homeostasis. This study recommends AM/AP in NFD at 0.60 to measure IEAA of broiler chickens.
... Nutrients are usually absorbed in the intestine through gastrointestinal digestion. During absorption, peptides are hydrolyzed further by pepsin and trypsin into smaller peptides or amino acids [42]. Therefore, the tolerance of purified peptides to pepsin and trypsin was evaluated to model and assess their stability in the digestive system. ...
Type I and V collagens are the major components of fibrillogenic proteins in fish skin, and their hydrolysis products possess hyaluronidase inhibitory activity. In this study, for the first time, type I and V collagens were isolated from the skin of shortbill spearfish and striped marlin. Type I (2α1[I]α2[I]) and type V (α1[V]α3[V]α2[V]) collagens composed of distinct α-peptide chains with comparable structures were investigated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and UV spectrophotometric chromatography. After enzymatic digestion, the collagen peptides were purified by using ultrafiltration (30 KDa) and high-performance liquid chromatography (RP-HPLC) to yield CPI-F3 and CPV-F4 fractions with strong hyaluronidase inhibition rates (42.17% and 30.09%, respectively). Based on the results of simulated gastrointestinal fluid, temperature, and pH stability assays, CPI-F3 and CPV-F4 exhibited stability in gastric fluid and showed no significant changes under the temperature range from 50 to 70 • C (p > 0.05). The results of this first research on the bioactivity of type V collagen peptides provide valuable information for the biomedical industry and show the potential for future bioactivity investigations of type V collagen and its peptides.
... The nourishment of goblet cells to form mucin depends mainly on the absorbed glutamine and glucose, which is easily provided by the prolamines and www.nature.com/scientificreports/ starch in grain 23 . Previous in vivo studies indicated that feeding starch increased mucus production in pigs and rats 24,25 . ...
Abstract The nitrogen-free diet (NFD) method is widely used to determine the ileal endogenous amino acids (IEAAs) losses in broiler chickens. Starch and dextrose are the main components of NFD, but the effects of their proportion in the NFD on the IEAAs and the digestive physiology of broilers are still unclear. This preliminary study aims to explore the best proportion of glucose and corn starch in NFD to simulate the normal intestinal physiology of broilers, which helps to improve the accuracy of IEAAs determination. For this purpose, 28-day-old broiler chickens were allocated to five treatment groups for a 3-day trial, including a control group and four NFD groups. The ratios of dextrose to corn starch (D/CS) in the four NFD were 1.00, 0.60, 0.33, and 0.14, respectively. Results noted that NFD significantly reduced serum IGF-1, albumin, and uric acid levels compared with the control (P
