Hey, welcome to the forum
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(a) Here, you a substituting a positively charged amino acid for another positively charged amino acid that looks identical. A hydrogen on the his-57 imidazole ring would not get transferred to the asp-102 carboxylate if you switch it to a lysine, which doesn't have an imidazole ring.
(b) Here, you a substituting a negatively charged amino acid for another negatively charged amino acid that looks identical. The hydrogen on the his-57 imidazole ring would likely not get transferred to the Glu's carboxylate, though I am not sure because both amino acids look nearly identical.
(c) Here, you a substituting a negatively charged amino acid for one that is polar charged. The hydrogen on the his-57 imidazole ring would not get transferred to Asn because it doesn't have a carboxylate.
(d) Recall that the hydrogen on the histidine imidazole ring is transferred to the asp-102 carboxylate (either via a "charge relay system" or via a "low barrier H-bond"). This shift results in the histidine ring being able to accept the ser-195 hydroxyl hydrogen, forming a very nucleophilic serine alkoxide ion. Thus, switching it for a cysteine would prevent the the histidine ring from being able to accept the cysteine because cysteine doesn't have a hydroxyl group!
(e) One very important and profound effect of this electrostatic interaction is the re-orientation of gly-193. In both the zymogen and the active enzyme the catalytic triad (Asp-102, His-57, and ser-195) is in a similar conformation, but Gly-193 is not. The NH group of Gly-193 forms a hydrogen bond with the substrate, which helps to correctly align the substrate with the catalytic residues. The fact that the catalytic residues are in the correct conformation in both the zymogen and the enzyme, indicate that the lack of catalytic activity in chymotrypsinogen is mainly due to an incomplete substrate binding site, and not necessarily the position of the catalytic residues alone. In this case Gly-193 needs to be in the correct orientation to align the substrate with the catalytic residues. The interaction of Ile-16 with Asp-194 causes this re-alignment.
Thus, switching it glycine for a larger, non-polar amino acid will prevent the NH group of valine from forming a hydrogen bond with the substrate, causing it not to align with the substrate.
Make sense?
Bio_man 8)
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