Peptidoglycan and Lysozyme

Flashcards covering key concepts related to peptidoglycan and lysozyme from the lecture notes.

Peptidoglycan

A polysaccharide-peptide conjugate found in bacterial cell walls.

Lysozyme

An antibacterial enzyme that cleaves peptidoglycan and leads to lysis of bacteria.

Covalent Catalysis

A catalytic process where a covalent bond forms between the enzyme and substrate during the reaction.

SN2 Mechanism

A type of nucleophilic substitution reaction where the bond-forming and bond-breaking occur simultaneously.

Glu35

A residue in lysozyme that acts as a general acid during the catalytic process.

Asp52

A residue in lysozyme that acts as a nucleophile in the first SN2 step.

General Base Catalysis

A process where a base removes a proton from a molecular species facilitating a reaction.

Glycosyl Carbocation Intermediate

A positively charged intermediate formed during the cleavage of peptidoglycan.

Transition State

A high-energy state during a chemical reaction that the reactants must pass through.

Hydrolysis

A chemical reaction involving the breaking of a bond in a molecule using water.

Cleavage of Peptidoglycan by Lysozyme

X-ray structures of lysozyme with bound substrate analogs show that the c-1 carbon is located between Glu35 and Asp52 residues.

Two SN2 steps of cleavage of peptidoglycan by lysozyme

Asp52 acts as a nucleophile to attach the anomeric carbon in the first SN2 step. Glu35 acts as a general acid andn protonates the leaving group in the transition state. Water hydrolyzes the covalent glycosyl-enzyme intermediate. Glu25 acts a a general base to deprotonate water in the second SN2 step.