Trivial enzyme kinetics question

kaj.stenberg at helsinki.fi.invalid kaj.stenberg at helsinki.fi.invalid
Sun Apr 21 03:58:28 EST 2002

A student asked a question regarding a calculation, the answer must be 
trivial but I don't get it:

>From a book (not at home so full reference missing):
E+P --k1,k-1--[ES]--k2-- E+P

A) what is the breakdown of ES. Because k2<<k1 k2 can be neglected, Kd
is k-1/k1. No problem.

B) Km is (k-1 + k2)/k1 

In case B, why can k2 not be neglected? (judging from the answer it
isn't, a factor of three difference. The ansver is in the 10E5 range)

Kaj Stenberg, Ph. D 
Department of Biosciences            tel. +358-9-191 59682
Division of Biochemistry             fax +358-9-191 59068
P. O. Box 56, Viikinkaari 5          e-mail: kaj.stenberg at helsinki.fi
FIN-00014 University of Helsinki     http://www.helsinki.fi/~kstenber/

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