Digestion chymotrypsin

Chymotrypsin specifically cleaves peptide bonds whose C-terminal amino acid is adjacent to non-polar aromatic amino acid residues or the bulky, hydrophobic methionine. Because these residues are often buried in the interior of proteins, including chymotrypsin, the self-hydrolysis of native, folded chymotrypsin is very inefficient. In fact, during digestion, chymotrypsin acts most effectively on partially degraded and denatured (unfolded) proteins. 

Let us look more closely at the chirality of enzymes. An illustration is chymotrypsin, an enzyme in the intestines of animals, which catalyzes the hydrolysis of proteins during digestion. Chymotrypsin, like all proteins, is composed of a long molecular chain of amino acids that folds up into the active enzyme. Human chymotrypsin has 268 chiral centers that result firom the amino acids so the maximum number of stereoisomers possible is 2 , a staggeringly large number, almost beyond comprehension. 

Chymotrypsin (Section 27 10) A digestive enzyme that cat alyzes the hydrolysis of proteins Chymotrypsin selectively catalyzes the cleavage of the peptide bond between the car boxyl group of phenylalanine tyrosine or tryptophan and some other ammo acid... 

The serine proteases are the most extensively studied class of enzymes. These enzymes are characterized by the presence of a unique serine amino acid. Two major evolutionary families are presented in this class. The bacterial protease subtilisin and the trypsin family, which includes the enzymes trypsin, chymotrypsin, elastase as well as thrombin, plasmin, and others involved in a diverse range of cellular functions including digestion, blood clotting, hormone production, and complement activation. The trypsin family catalyzes the reaction ... 

Huxley suggested that crossbridges can move out in this way and bind to actin because S-2 of HMM acted as a flexible link between LMM in the thick filament backbone and S-1. This was based on the observation that heavy meromyosin could be digested by chymotrypsin into two further subffagments (Lowey et al., 1966), S-1 and S-2, as described above, and that S-1 contained the ATPase and actin binding sites, whereas S-2 did not moreover, S-2 did not self-aggregate, as did the rod or LMM portion of myosin. 

There are two main classes of proteolytic digestive enzymes (proteases), with different specificities for the amino acids forming the peptide bond to be hydrolyzed. Endopeptidases hydrolyze peptide bonds between specific amino acids throughout the molecule. They are the first enzymes to act, yielding a larger number of smaller fragments, eg, pepsin in the gastric juice and trypsin, chymotrypsin, and elastase secreted into the small intestine by the pancreas. Exopeptidases catalyze the hydrolysis of peptide bonds, one at a time, fi"om the ends of polypeptides. Carboxypeptidases, secreted in the pancreatic juice, release amino acids from rhe free carboxyl terminal, and aminopeptidases, secreted by the intestinal mucosal cells, release amino acids from the amino terminal. Dipeptides, which are not substrates for exopeptidases, are hydrolyzed in the brush border of intestinal mucosal cells by dipeptidases. 

The cysteinyl residue in the core was oxidized with performic acid according to the method of Hirs ( ) and the oxidized core was digested with chymotrypsin for 8 hours at room temperature in a pH stat at pH 8.9. Enzyme equal to 0.5% of the substrate by weight was added at 0 and at 2 hr. The chymotryptic peptides were also separated by Dowex 50-X4 chromatography. 

Inactivation due to digestive proteases. Therapeutic proteins would represent potential targets for digestive proteases such as pepsin, trypsin and chymotrypsin. 

The catalytic mechanism of the subtilisins is the same as that of the digestive enzymes trypsin and chymotrypsin as well as that of enzymes in the blood clotting cascade, reproduction and other mammalian enzymes. The enzymes are known as serine proteases due to the serine residue which is crucial for catalysis (Kraut, 1977 and Polgar, 1987)... 

Further confirmation for the location of the membrane-spanning domains of the El and of the E2 polypeptide chains has come from studies of Sindbis virus. After chymotrypsin digestion of the viral particle, the... 

The Pharmaceutical Industiy. Pepsin, trypsin and chymotrypsin have been used clinically as a digestive aid, especially when coated to protect against damage in the stomach, and also in the preparation of precooked cereals and baby foods. Proteases have also been used medically for fibrinolysis, as anti-inflammatory agents in the potentiation of drug activity, and in the treatment of cystic fibrosis, burns, ulcers and acne. 

A large group of proteinases contain serine in their active center. The serine proteases include, for example, the digestive enzymes trypsin, chymotrypsin, and elastase (see pp. 94 and 268), many coagulation factors (see p. 290), and the fibrinolytic enzyme plos-min and its activators (see p. 292). 

The digestive enzyme chymotrypsin has a serine in its active site that acts as a general base or proton acceptor during hydrolysis of peptide bonds in protein substrates (Figure 3-2). 

The porcine insulin is first subjected to digestion with chymotrypsin-free trypsin at pH 7.5 for in excess of 45 min. This results in the selective cleavage of the peptide bond linking arginine 22... 

Asafetida, administered orally to albino rats at a dose of 250 mg% for 8 weeks, enhanced pancreatic lipase activity, stimulated pancreatic amylase and chymotrypsin. The stimulatory influence was not observed when their intake was restricted to a single oral dose " " ". Protein digestibility. Asafetida did not affect the digestibility of protein in sorghum " . ... 

Trypsin is responsible for the activation of chymotrypsin, as well as for a range of other digestive enzymes synthesized in the pancreas. Trypsin itself is formed from its zymogen via digestion by the enzyme enteropeptidase. Enteropeptidase is secreted from intestinal cells and cleaves trypsinogen to trypsin as soon it travels from the pancreas to the intestine. 

Proteins are hydrolyzed to a-amino acids by heating with aqueous strong acids or, at room temperature, by digestive enzymes such as trypsin, chymotrypsin, or pepsin. 

---