Gastrointestinal Function and Toxicology in Canines
Shayne C. Gad in Toxicology of the Gastrointestinal Tract, 2018
The total pancreatic secretion is capable of hydrolyzing fats, proteins, and carbohydrates and the character of the pancreatic secretion can be modified by the character of the chyme itself. Disaccharides and trisaccharides are products of the action of pancreatic amylase on such substrates as glycogen, starches, and most other carbohydrates. Neutral fats are reduced to fatty acids and monoglycerides under the action of pancreatic lipase. Pancreatic phospholipase and cholesterol esterase produce fatty acids and phospholipids and fatty acids and cholesterol, respectively. The most important and abundant pancreatic proteolytic enzyme is trypsin. Carboxypeptidase and chymotrypsin are also proteolytic enzymes of importance but are found to be present in lesser amounts than trypsin. Nucleases and elastases are also present in pancreatic secretions but are of lesser importance and in small amounts. Proteolytic enzymes produced by the pancreas are in enzymatically inactive forms, which are activated only upon entry into the gastrointestinal tract. This activation is achieved by the presence of kinases produced by the gastrointestinal mucosa and to a lesser degree by autocatalysis. The actions of nucleases and elastases are obvious. Trypsin and chymotrypsin cleave proteins and large polypeptides in such a fashion as to produce smaller peptides, but not individual amino acids. Carboxypeptidase, however, does hydrolyze peptides into individual amino acids.
The Renin-Angiotensin System
Austin E. Doyle, Frederick A. O. Mendelsohn, Trefor O. Morgan in Pharmacological and Therapeutic Aspects of Hypertension, 2020
However, very high concentrations of angiotensin I may be handled in a different manner.251 Using near-physiological concentrations of angiotensin I injected into the pulmonary arteries of anesthetized rats, only angiotensin II and unaltered angiotensin I were found in the pulmonary venous effluent, indicating the action of converting enzyme. However, when higher doses of angiotensin I were administered, the converting enzyme appeared to become saturated, and a peptide resembling [des-Leu10]-angi-otensin I was found in the venous effluent in large quantities. The appearance of this peptide fragment indicates the action of a carboxypeptidase. The authors suggested that this dual enzyme system might allow protective inactivation of excessive amounts of angiotensin I reaching the lungs.
Biocatalyzed Synthesis of Antidiabetic Drugs
Peter Grunwald in Pharmaceutical Biocatalysis, 2019
For these biotransformations, five steps were required (Barfoed, 1987): Insulin was first extracted from frozen porcine pancreas glands, purified and converted into human insulin in a medium that contains only a small amount of water and trypsin and a large quantity of organic solvent and threonine ester. Thus, trypsin hydrolyzed insulin at LysB29-AlaB30, while at the same time catalyzed the reverse reaction in which the threonine ester displaces alanine from position B30 in the insulin molecule. This transpeptidation of porcine insulin to human insulin was optimized to 97% yield using soluble trypsin (Morihara et al., 1979), and followed by chromatographic purification to reduce measurable levels of proinsulin and remove the other reagents, pharmaceutical formulation and distribution into the market. Finally, the product was formulated and then filled under sterile conditions, packaged, and distributed. Transpeptidation could be also catalyzed by immobilized trypsin, although the reported yield was lower, around 80% (Ueno and Morihara, 1989). Another protease, from Achromobacter lyticus, was also found to be completely specific for the hydrolysis of LysB29-AlaB30 and the subsequent condensation con H-Thr-OBut (Morihara et al., 1980; Morihara and Ueno, 1991). Similarly, the use of carboxypeptidase A for the same procedure was described (Andresen et al., 1983).
Comprehensive characterisation of the heterogeneity of adalimumab via charge variant analysis hyphenated on-line to native high resolution Orbitrap mass spectrometry
Published in mAbs, 2019
Florian Füssl, Anne Trappe, Ken Cook, Kai Scheffler, Oliver Fitzgerald, Jonathan Bones
Using our native CVA-MS approach, we were able to obtain very high chromatographic resolution and successful identification of the majority of the 16 charge variants observed. Among them were proteoforms modified by different levels of C-terminal lysine truncation, deamidation, succinimide aspartic acid (Asp) formation, glycation and fragmentation. To investigate whether host cell proteins (HCPs) might be involved in the fragmentation of adalimumab, we performed an HCP analysis employing peptide mapping. Several HCPs were detected, among them the protease Cathepsin L, which could suggest the occurrence of the detected fragments to partly be due to enzymatic proteolysis. Carboxypeptidase B (CpB) digestion and peptide mapping experiments were performed as orthogonal methods to confirm the results obtained on the intact protein level.
Is individual genetic susceptibility a link between silica exposure and development or severity of silicosis? A systematic review
Published in Inhalation Toxicology, 2020
Kaio Cezar Rodrigues Salum, Marcos Cesar Santos Castro, Ângela Santos Ferreira Nani, Fabiana Barzotto Kohlrausch
Carboxypeptidase M (CPM) belongs to the family of the carboxypeptidases, which function is removing C-terminal amino acids from peptides and proteins and exert roles in physiological processes like inflammation. CPM has been suggested to play critical roles in inflammatory diseases (Deiteren et al. 2009), and a higher expression level of CPM may promote the progression of lung fibrosis (Chu et al. 2019). In fact, the relative expression of the CPM gene was significantly higher in subjects with silicosis compared with healthy controls (Chu et al. 2019). Based on the hypothesis that the rs12812500 polymorphism is located on the promoter of the CPM gene and was associated with higher CPM expression, Chu et al. (2019) evaluated this polymorphism and observed the G allele was associated with an increased risk of silicosis in an additive genetic model controlled for confounders.
Recent advances in proteolytic stability for peptide, protein, and antibody drug discovery
Published in Expert Opinion on Drug Discovery, 2021
Xianyin Lai, Jason Tang, Mohamed E.H. ElSayed
Carboxypeptidases (EC 3.4.16–3.4.18) are peptidases that cleave a peptide bond at the carboxy-terminal (C-terminal) end of a peptide or protein. Carboxypeptidases are named with a combination of one letter and one number following the word carboxypeptidase at the beginning. There are at least 17 carboxypeptidases, belonging to two major groups. One uses serine as an active site residue named as serine carboxypeptidases, and the other uses zinc at the active site, known as metallocarboxypeptidases, which are further separated into two subgroups based on amino acid sequence similarities [66]. Among the carboxypeptidases, some of them have low tissue specificity with expression in many tissues and are secreted into bodily fluids with a low concentration, such as carboxypeptidases D and X2. Some are in specific tissues without leaking into bodily fluids or with a low concentration in bodily fluids, such as carboxypeptidase A4 in the esophagus and skin, carboxypeptidase A6 in the intestine, prostate, and retina, carboxypeptidase E in the brain, carboxypeptidase M in the adipose, carboxypeptidase O in the intestine, X1 in the placenta, and carboxypeptidase Z in the ovary. And others are produced in specific tissues and then secreted into either small intestinal fluid or blood. Carboxypeptidases A1, A2, and B1 are produced in the pancreas and activated in the duodenum. All three proteins are zinc-containing metallopeptidases [67]. Compared to the high abundance of trypsin, chymotrypsin and elastase in the small intestine, carboxypeptidases such as A1, A2, and B1, have a much lower concentration.
Related Knowledge Centers
- Aminopeptidase
- Enzyme
- Hydrolysis
- Peptide
- Peptide Bond
- Protease
- Protein
- Enzyme Commission Number
- C-Terminus
- N-Terminus