The orientation and accessibility of substrates on the active site of triosephosphate isomerase

Biochemistry. 1975 Oct 21;14(21):4692-8. doi: 10.1021/bi00692a020.


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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Binding Sites
  • Borohydrides
  • Carbohydrate Epimerases / metabolism*
  • Chickens
  • Glycerophosphates / metabolism*
  • Muscles / enzymology
  • Oxidation-Reduction
  • Protein Binding
  • Stereoisomerism
  • Structure-Activity Relationship
  • Triose-Phosphate Isomerase / metabolism*
  • Tritium


  • Borohydrides
  • Glycerophosphates
  • Tritium
  • Carbohydrate Epimerases
  • Triose-Phosphate Isomerase