Trypsin chymotrypsin and

This is nicely illustrated by members of the chymotrypsin superfamily the enzymes chymotrypsin, trypsin, and elastase have very similar three-dimensional structures but different specificity. They preferentially cleave adjacent to bulky aromatic side chains, positively charged side chains, and small uncharged side chains, respectively. Three residues, numbers 189, 216, and 226, are responsible for these preferences (Figure 11.11). Residues 216... 

Figure 11.11 Schematic diagrams of the specificity pockets of chymotrypsin, trypsin and elastase, illustrating the preference for a side chain adjacent to the scisslle bond In polypeptide substrates. Chymotrypsin prefers aromatic side chains and trypsin prefers positively charged side chains that can interact with Asp 189 at the bottom of the specificity pocket. The pocket is blocked in elastase, which therefore prefers small uncharged side chains.

Selected entries from Methods in Enzymology [vol, page(s)] Sulfonylation reaction, 11, 706 reaction kinetics, 11, 707 second-order rate constants for inactivation of chymotrypsin, trypsin, and acetylcholine esterase by PMSE and related sulfonylat-ing agents, 11, 707 reactivation of PMS-chymotrypsin, 11, 710 as inhibitor [of calcium-activated factor, 80, 674 of cathepsin G, 80, 565 of crayfish trypsin, 80, 639 of elastase, 80, 587 of pro-lylcarboxypeptidase, 80, 465 of protease Re, 80, 691 of protease So, 80, 695 of protein C, 80, 329] proteolysis, 76, 7. 

Chymotrypsinogen consists of a single 245-residue chain. The amino acid residues in chymotrypsin, trypsin, and elastase are usually all numbered according to their position in this zymogen. Inactive proenzymes are formed as precursors to enzymes of many different classes and are activated in a variety of ways. A part of the polypeptide chain of the proenzymes is often folded over the active site, interacting in a nonsubstrate-like fashion and blocking the site.197a... 

Chromophoric inhibitor displacement.6 1 The spectrum of the dye proflavin changes significantly with solvent polarity. It is a competitive inhibitor of chymotrypsin, trypsin, and thrombin, and it undergoes a large increase in absorbance at 465 nm (Ae 2 X 104 M l cm 1) on binding (Figure 7.1). 

Schematic diagrams of the amino acid sequences of chymotrypsin, trypsin, and elastase. Each circle represents one amino acid. Amino acid residues that are identical in all three proteins are in solid color. The three proteins are of different lengths but have been aligned to maximize the correspondence of the amino acid sequences. All of the sequences are numbered according to the sequence in chymotrypsin. Long connections between nonadjacent residues represent disulfide bonds. Locations of the catalytically important histidine, aspartate, and serine residues are marked. The links that are cleaved to transform the inactive zymogens to the active enzymes are indicated by parenthesis marks. After chymotrypsinogen is cut between residues 15 and 16 by trypsin and is thus transformed into an active protease, it proceeds to digest itself at the additional sites that are indicated these secondary cuts have only minor effects on the enzymes s catalytic activity. (Illustration copyright by Irving Geis. Reprinted by permission.)...

Organophosphorus compounds bearing a fluorescent group were specifically introduced into the active sites of the serine-enzymes -Chymotrypsin, Trypsin and Butyrylcholin-esterase using the agents 2, 3i and 4. This was shown using electrophoresis. 

Within each protease family, individual members will differ in their substrate specificity. Most proteases have extended substrate binding sites and will bind to and recognize several amino acid residues of a polypeptide substrate (see Figure 2). Usually one of these will be the primary binding site. For example, in the serine proteases chymotrypsin, trypsin, and elastase, the primary substrate binding site is the Si subsite... 

This group includes the chymotrypsins, trypsin, elastase, thrombin, and subtilisin. The name of this group of enzymes refers to the seryl residue that is involved in the active site. As a consequence, all of these enzymes are inhibited by diisopropylphosphorofluori-date, which reacts with the hydroxyl group of the seryl residue. They also have an imidazole group as part of the active site and they are all endopeptides. The chymotrypsins, trypsin and elastase, are pancreatic enzymes that carry out their function in the intestinal... 

Figure 9.13. The Sj Pockets of Chymotrypsin, Trypsin, and Elastase. Certain residues play key roles in determining the specificity of these enzymes. The side chains of these residues, as well as those of the active-site serine residues, are shown in color.

Initial attempts to achieve an enzyme-catalyzed deprotection of the carboxy group of peptides centred around the use of the endopeptidases chymotrypsin, trypsin,and thermolysin.P l Thermolysin is a protease obtained from Bacillus thermoproteolyticus that hydrolyzes peptide bonds on the annino side of the hydrophobic amino acid residues (e.g., leucine, isoleucine, valine, phenylalanine). It cleaved the supporting tripeptide ester H-Leu-Gly-Gly-OEt from a protected undecapeptide (pH 7, rt). The octapeptide, thus obtained, is composed exclusively of hydrophilic annino acids. Due to the broad substrate specificity of thermolysin and the resulting possibility of unspecific peptide hydrolysis, this method is of limited application. 

B-esterases are the group of enzymes that can be inhibited by organophos-phorus compounds in the reaction that is time- and temperature-dependent. This group of enzymes comprises CarbE, AChE (EC 3.1.1.7), serum cholinesterase (ChE EC 3.1.1.8), chymotrypsin, trypsin and some other enzymes. A common feature of these enzymes is that they have serine hydroxyl group at the active site that enables them to react with OPC in the similar fashion (Figure 3). From the... 

Proteolytic enzymes (proteases) catalyze the hydrolysis of peptide bonds. The pancreatic serine proteases chymotrypsin, trypsin, and elastase have similar structures and mechanisms of action, but different substrate specificities. It is thought that they evolved from a common ancestral protease. 

What do the similar structures of chymotrypsin, trypsin, and elastase suggest about their evolutionary relationship ... 

The 2-oxazolin-S-ones are excellent acylating agents for a variety of enzymes. Thus, 2-phenyloxazolin-5-one and 4,4-dimethyl-2-phenyl-2-oxazolin-S-one react with a-chymotrypsin, trypsin, and papain to form stable acyl enzymes.15-18 The azlactone from p-nitrobenzoylvaline reacted with a-chymotrypsin and trypsin, and it was observed that the enzymic activity of chymotrypsin decreased with increasing number of p-nitrobenzoylvaline residues.19 The reaction of a-chymotrypsin with 2 has been studied extensively.20-25 In this reaction, the oxazolone dis-... 

White powder. Isoelectric point 4.6 (sheep), 7.45 (pig). Soluble in water. Chymotrypsin, trypsin and pepsin destroy the gonadotrop(h)ic action of LH. Picrolonic, flavianic. picric, and trichloroacetic acids precipitate LH with retention of its physiological activity. therap cat Gonadotropic hormone. 

As one might expect, water has a dramatic effect on enzyme stability in SCFs. Lozano et al. found that the half-life time of a-chymotrypsin decreased exponentially in SCCO2 with increasing water content from 0 to 15 wt% [28]. Kashe et al. found that a-chymotrypsin, trypsin and penicillin amidase partially unfolded during pressure reduction in humid SCCO2. They suggested that... 

Proteins are hydrolytically cleaved at the peptide linkages by proteases (peptidases, EC3.4.-.-) (Beynon and Bond, 2001 Sterchi and Stdkenn, 1999). Two classes of peptidases are endopeptidases, which cleave internal bonds (e.g. chymotrypsin, trypsin), and exopeptidases, which hydrolyze the terminal residue of a polypeptide chain (e.g. aminopeptidases, carboxypeptidases). Table 12.10 lists some of the common proteases classified mechanistically according to their characteristics. 

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