Stereoselective reactivity of the SH groups of yeast glyceraldehydephosphate dehydrogenase in the allosteric T and R states

B Eisele; K Wallenfels

doi:10.1016/0014-5793(68)80009-2

Stereoselective reactivity of the SH groups of yeast glyceraldehydephosphate dehydrogenase in the allosteric T and R states

FEBS Lett. 1968 Jul;1(1):25-28. doi: 10.1016/0014-5793(68)80009-2.

Authors

B Eisele¹, K Wallenfels

Affiliation

¹ Chemisches Laboratorium der Universität Freiburg/Br., Switzerland

PMID: 11945243
DOI: 10.1016/0014-5793(68)80009-2

Abstract

Yeast glyceraldehyde-3-phosphate dehydrogenase as a typical SH enzyme is inactivated by the antipodes of a-iodopropionic acid and its amide at different rates. The apoenzyme reacts faster with the D(+) antipode of the free a-iodopropionic acid (k(D)/k(L) = 6.8) and the L(-) antipode of the amide (k(L)/k(D) = 3). On addition of NAD(+) the stereoselectivity of the SH group towards a-iodopropionic acid is inverted, that towards the amide is enlarged, the rate relationships depending on the NAD(+) concentration.The results were interpreted by the assumption, that the allosteric T state of the enzyme reacts most rapidly with the D(+) antipodes, whereas the R state favours the L(-) antipodes of the alkylation reagents. The dependence of the reaction rates on the NAD(+) concentration could be fitted to the allosteric function of state R.