Oligomerization studies of Leuconostoc mesenteroides G6PD activity after SDS-PAGE and blotting

Glucose6phosphate dehydrogenase (G6PD) is a ubiquitous enzyme catalyzing the oxidation of Dglucose 6phosphate to Dglucono⎯lactone 6phosphate, in the first step of the pentose phosphate path way. Based on the currently available structural information on Leuconostoc mesenteroides G6PD, it is believed that the enzyme only works as a homodimer. Here we show that both after nondenaturing and after denaturing electrophoretic separation (SDSPAGE) and blotting L. mesenteroides G6PD retains its complete catalytic activity. In the two latter cases the molecular weight of the band corresponded to that of a G6PD monomer. Conversely, when the same technique was applied to G6PD from Saccharomyces cerevisiae, another fermentative organism, the monomer activity was not detectable after SDSPAGE and blotting. The results are discussed in terms of molecular evolution of the oligomeric state in the various G6PD sources.