Which of the following causes hydrolysis of Peptidoglycans?
Correct Answer: Lysozyme
Description: The enzyme functions by attacking peptidoglycans (found in the cell walls of bacteria, especially Gram-positive bacteria) and hydrolyzing the glycosidic bond that connects N-acetylmuramic acid with the fouh carbon atom of N-acetylglucosamine. It does this by binding to the peptidoglycan molecule in the binding site within the prominent cleft between its two domains. This causes the substrate molecule to adopt a strained conformation similar to that of the transition state. According to Phillips-Mechanism, the lysozyme binds to a hexasaccharide. The lysozyme then distos the fouh sugar in hexasaccharide (the D ring) into a half-chair conformation. In this stressed state, the glycosidic bond is easily broken. The amino acid side-chains glutamic acid 35 (Glu35) and aspaate 52 (Asp52) have been found to be critical to the activity of this enzyme. Glu35 acts as a proton donor to the glycosidic bond, cleaving the C-O bond in the substrate, whereas Asp52 acts as a nucleophile to generate a glycosyl-enzyme intermediate. The glycosyl-enzyme intermediate then reacts with a water molecule, to give the product of hydrolysis and leaving the enzyme unchanged
Category:
Biochemistry
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