E. cob D-glyceraldehyde-3-phosphate dehydrogenase covalently bound to Sepharose was shown to form a complex with soluble E. coR 3-phosphoglycerate kinase with a stoichiometry of 1.77~_0.61 kinase molecules per tetramer of the dehydrogenase and an apparent K., of 1.03+0.68/tM (10 mM sodium phosphate, 0.15 M Noel). No interaction was detected between E. colt t>glyceraldehyde-3-phosphate dehydrog~nase and rabbit muscle 3.phosphoglycerate kinase. The species-specificity of the bienzyme association made it possible to develop a kinetic approach to demonstrate the functionally significant interaction between E. colt o-glyceraldehyde-3-phosphate dehydrogenase and E. colt 3.phosphoglycerate kinase, which consists of an increase in steady-state rate of the coupled reaction.~.Clyeeraldehyde.3-phosphate dehydrogenase; 3-Phosphoglycerate kinase; Bienzyme complex