An emerging picture in enzymology is that catalytic active site residues can perform multiple rate-enhancing features simultaneously. In triosephosphate isomerase (TIM) it is known that a glutamate acts as a general base; however, this residue may also contribute to catalysis via ground state destabilization. To systematically evaluate the contribution of the general base to both catalysis and ground state destabilization, we mutated the glutamate to uncharged polar and non-polar residues. Ablation of the general base led to a substantial 104-fold decrease in activity with little catalytic variation between mutants. Binding affinity experiments revealed an increase of 10 3 -fold in analog affinity for mutants lacking the charged general base supporting the presence of ground state destabilization in TIM.
|Advisor:||Schwans, Jason P.|
|Commitee:||Acey, Roger, Narayanaswami, Vasanthy|
|School:||California State University, Long Beach|
|Department:||Chemistry and Biochemistry|
|School Location:||United States -- California|
|Source:||MAI 54/06M(E), Masters Abstracts International|
|Keywords:||Catalysis, Enzyme, General base, Ground state destabilization, Triose phosphate isomerase|
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