A comparative study of some of the enzymes involved in glucose metabolism of human diploid and SV40-transformed human diploid cells.

All of the glycolytic enzymes with the exception of enolase and phosphoglyceromutase were measured for WI-38, human embryonic lung tissue, and its SV40-transformed counterpart, WI-38VA13A. Also measured were glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucomutase, and fructose 1,6-diphosphatase. Enzyme activity per IO6 cells indicated that glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, hexokinase, fructose 1 ,6-diphosphatase, and glyceraldehyde 3-phosphate dehydrogenase were 2.1-, 1.6-, 2.4-, 2.9-, and 2.1-fold greater, respectively, in WI-38 than in WI-38VA13A. The pH optima and kinetic properties for hexokinase, glucose 6-phosphate dehydrogenase, and glyceraldehyde 3-phosphate dehydrogenase were determined for both sources. The only significant difference in these properties was the greater affinity for NAD* exhibited by the glyceraldehyde 3-phosphate dehydrogenase from WI-38 (Km = 0.07 mM) when compared to the WI-38VA13A enzyme (Km = 0.26 mM). From the work, it was suggested that the greater glucose consumption and láclate production observed for growing WI-38 compared to WI-38VA13A is probably in part a consequence of hexokinase and glyceraldehyde 3-phosphate dehydrogenase levels in WI-38.