The orientation and accessibility of substrates on the active site of triosephosphate isomerase.
Tritiated sodium borohydride was used to reduce the substrates of triosephosphate isomerase in the presence of the enzyme, and the mixture of the four possible products (D-[1(R)-3H]; D-[1(S)-3H]-; D-[2-3H]-, and L-[2-3H]glycerol 3-phosphate) was analyzed. While enzyme-bound dihydroxyacetone phosphate is reduced completely stereoselectively and at a rate eight imes faster than in free solution, D-glyceraldehyde 3-phosphate is inaccessible to reduction by borohydride when bound to the active site of the enzyme.
D000818:Animals; D001665:Binding Sites; D001894:Borohydrides; D002238:Carbohydrate Epimerases / Q000378:metabolism*; D002645:Chickens; D005994:Glycerophosphates / Q000378:metabolism*; D009132:Muscles / Q000201:enzymology; D010084:Oxidation-Reduction; D011485:Protein Binding; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D014305:Triose-Phosphate Isomerase / Q000378:metabolism*; D014316:Tritium
D001894:Borohydrides; D005994:Glycerophosphates; D014316:Tritium; D002238:Carbohydrate Epimerases; D014305:Triose-Phosphate Isomerase