Catalytic triads consisting of acid base and nucleophilic...

Catalytic triads consisting of acid, base, and nucleophilic residues, such as the Asp-His-Ser triad found in chymotrypsin, are commonly found in protease enzymes. What other two amino acid residues are likely to act as nucleophilic residues in catalytic triads? How would the different properties (pKa and size/structure) of each of these two amino acid residues compare to serine in their use as components of a catalytic triad?

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00:01 Hello everyone in this question they are asking about the catalytic triad so here are acid base nucleophile so this combination will act as a catalytic triad of an enzyme so actually what this do this activates the nucleophile this activates the nucleophile so after activating the nucleophile what will happen this attacks on the substance to form a covalently bonded interming so after that one, it attacks on a substance and it forms a covalently bonded intermediate.

00:44 Covalently bonded intermediate.

00:51 So then this intermediate which after hydrolysis, it gives a product and regenerate the enzyme.

00:57 What is that enzyme? that enzyme is chlorochromyptin.

01:07 That enzyme is chromatripsin.

01:09 So how it will be? it has contained three groups asp, histidine and serine.

01:15 So this one is act as an acid, this is a base, and what about this one? this one is nucleophile.

01:24 This one is a nucleophile.

01:25 So in this catalytic triad, for this cysteine, this cysteine in this catalytic triad and three on nine, these two are act as a nucleophilic residues.

01:39 These two are act as a nucleophilic residues.

01:45 Nucleophilic residues.

01:47 So here, if you draw the structure of this cysteine and threonine, so this one is the structure of the cysteine.

01:55 It will be like this.

01:59 It will contain ethyol group...

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