scholarly journals Enzymatic Catalysis of Proton Transfer at Carbon:  Activation of Triosephosphate Isomerase by Phosphite Dianion†

Biochemistry ◽  
2007 ◽  
Vol 46 (19) ◽  
pp. 5841-5854 ◽  
Author(s):  
Tina L. Amyes ◽  
John P. Richard
Keyword(s):  
Proton Transfer ◽  
Triosephosphate Isomerase ◽  
Enzymatic Catalysis

scholarly journals Enzymatic catalysis of proton transfer and decarboxylation reactions

2011 ◽  
Vol 83 (8) ◽  
pp. 1555-1565 ◽  
Author(s):  
John P. Richard
Keyword(s):  
Proton Transfer ◽  
Active Sites ◽  
Triosephosphate Isomerase ◽  
Enzymatic Catalysis ◽  
Enzymatic Reaction ◽  
Dihydroxyacetone Phosphate ◽  
Enzymatic Reactions ◽  
Exchange Reactions ◽  
Monophosphate Decarboxylase ◽  
The Stability

Deprotonation of carbon and decarboxylation at enzyme active sites proceed through the same carbanion intermediates as for the uncatalyzed reactions in water. The mechanism for the enzymatic reactions can be studied at the same level of detail as for nonenzymatic reactions, using the mechanistic tools developed by physical organic chemists. Triosephosphate isomerase (TIM)-catalyzed interconversion of D-glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP) is being studied as a prototype for enzyme-catalyzed proton transfer, and orotidine monophosphate decarboxylase (OMPDC)-catalyzed decarboxylation of orotidine 5'-monophosphate (OMP) is being studied as a prototype for enzyme-catalyzed decarboxylation. 1H NMR spectroscopy is an excellent analytical method to monitor proton transfer to and from carbon catalyzed by these enzymes in D2O. Studies of these partial enzyme-catalyzed exchange reactions provide novel insight into the stability of carbanion reaction intermediates, which is not accessible in studies of the full enzymatic reaction. The importance of flexible enzyme loops and the contribution of interactions between these loops and the substrate phosphodianion to the enzymatic rate acceleration are discussed. The similarity in the interactions of OMPDC and TIM with the phosphodianion of bound substrate is emphasized.

Energetics of triosephosphate isomerase: the nature of the proton transfer between the catalytic base and solvent water

Biochemistry ◽  
1976 ◽  
Vol 15 (25) ◽  
pp. 5621-5626 ◽  
Author(s):  
L. Mark Fisher ◽  
W. John Albery ◽  
Jeremy R. Knowles
Keyword(s):  
Proton Transfer ◽  
Triosephosphate Isomerase ◽  
Solvent Water
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