A NEW LEASE OF LIFE FOR AN OLD ENZYME

We review here some recent data about glucose-6-phosphate dehydrogenas e (G6PD), the first and key regulatory enzyme of the pentose phosphate pathway. New evidence has been presented to suggest that malaria is a selective agent for G6PD deficiency, which is the most common enzymop athy in man, and that G6PD deficiency, generally considered to be a mi ld and benign condition, is significantly disadvantageous in certain e nvironmental conditions. At the molecular level, the enzyme structure has recently been elucidated and mechanisms regulating G6PD gene expre ssion have been determined. A G6PD knock-out mutation introduced in mo use cells makes them exquisitely sensitive to oxidative stress, indica ting that this ubiquitous metabolic enzyme has a major role in the def ence against oxidative stress, even in eukaryotic nucleated cells, whi ch have several alternative routes for providing the same protection. Because of the high prevalence of G6PD deficiency in many populations, it is expected that these findings will prompt further studies to asc ertain the putative role of G6PD deficiency in conditions such as carc inogenesis and ageing.