This preview shows page 1. Sign up to view the full content.
Unformatted text preview: Homework Answers #1 1. Assume that the overall reaction requires two separate catalytic sites, A and B. Suppose further that mutation A- inactivates catalytic site A, and mutation Binactivates catalytic site B. Then, either of these mutations will prevent the overall reaction if all copies of the protein contain the mutation. Now separate the tetramers of the two mutant proteins into their component monomers, and mix them. The monomers in the mixture have only two possible compositions: A+B- and A-B+, where a superscript “+” denotes the wild-type protein at a particular catalytic site and superscript “-“ again denotes a mutation. The tetramers formed from the mixture can have 5 possible compositions: (A+B-)4, (A+B-)3(A-B+)1, (A+B-)2(A-B+)2, (A+B-)1(A-B+)3 and (A-B+)4. If both catalytic steps must occur in the same monomeric subunit, all these hybrid tetramers will be inactive. But if reactions A and B can occur in different in different subunits of the tetramer, the second, third and fourth type of hybrid will be able to catalyze the overa...
View Full Document
This note was uploaded on 02/02/2010 for the course BIOCHEMIST Biochem 44 taught by Professor Parson,young during the Winter '10 term at University of Washington.
- Winter '10