chymotrypsin mechanism

[bebe1018_87]

Chymotrypsin mechanism?

what are the correct steps for the mechanism of chymotrypsin?

 

Below is my answer but I don't know if it is right.

 

 

a) His 57 catalyzes removal of H from Ser 195 hydroxyl.

b. Ser 195's nucleophilic O attacks carbonyl C of substrate.

c. His 57 donates H to N of sissile peptide bond, tetrahedral intermediate decomposes.

d. C- terminal portion of oribinal substrate with its new amino acid terminus diffuses away.

e. water donates H to His 57.

f. Resulting OH attacks carbonyl of remaining substrate.

g. His 57 donates H to Ser 195 O, leading to collapse of tetrahedral intermediate.

h.N-terminal portion of original substrate with its new carboxy terminus diffuses away.

 

My answer is b,a,c,e,f,g,h,d. Is this right? Thank you!

[CharonY]

Eh, wait somehow did read the question wrong.The suggested order would not work. For instance, do you think that the nucleophilic attack would work as the first reaction? I.e. does the hydroxyl group has a reasonable chance to form a covalent bond with the C of the substrate?

Edited October 8, 2010 by CharonY