Lysozyme

How is lysozyme example of divergent evolution?

similar to mammalian lactalbumin but lysozyme doesn't have calcium binding site

What does lysozyme do?

destroy bacterial cell walls, hydrolyses beta (1,4) glycosidic linkages of N-acetylmuramic acid-N-acetylglucosamine linkages

What is peptidoglycan structure

6 nag-nam units

When are D-amino acids used in conjunction with L-amino acids?

Pentapeptide attached to NAM in NAM-NAG unit in neisseria meningitis

How does peptidoglycan gram positive and gram-negative structure differ?

gram positive has large peptidoglycan, gram negative has outer membrane therefore an extra periplasmic space and small peptidoglycan

How are Nag-Nam units cleaved?

hydrolysis

What type of mechanism does lysozyme use?

retaining

What is near the active site in lysozyme?

aromatic amino acid

What conformation change is needed for active site?

chair to half-chair to reduce steric clash and make it more likely to cleave

Where is the steric clash in lysozyme?

Between 4th residue C6 and O6

How was mechanism recently discovered for lysozyme?

through fluoride incubation and mutation of Glu to gln

Is there a catalytic intermediate in the cleavage?

yes