Activity of selected gluconeogenic and lipogenic enzymes in bovine rumen mucosa, liver and adipose tissue.
The activities of phosphoenolpyruvate carboxykinase, ;malic enzyme', citrate-cleavage enzyme and glucose 6-phosphate dehydrogenase were assayed in homogenates of rumen mucosa, liver and adipose tissue of cattle. Rumen mucosa cytoplasm contained activities of ;malic enzyme' approximately sevenfold those of phosphoenolpyruvate carboxykinase, suggesting that the conversion of propionate into lactate by rumen mucosa involves ;malic enzyme'. Neither starvation for 8 days nor feeding with a concentrate diet for at least 3 months before slaughter produced enzyme patterns in the tissues different from those in cattle given only hay, except that the all-concentrate diet caused increased activities of glucose 6-phosphate dehydrogenase and ;malic enzyme' in adipose tissues. Rumen mucosa, liver and adipose tissue contained phosphoenolpyruvate carboxykinase activity. ;Malic enzyme' was absent in liver. Citrate-cleavage enzyme activity was present in liver and adipose tissue but was quite low in rumen mucosa. Liver contained much less glucose 6-phosphate dehydrogenase activity than rumen mucosa or adipose tissue.
D000273:Adipose Tissue / Q000201:enzymology*; D000818:Animals; D002262:Carboxy-Lyases / Q000032:analysis; D002417:Cattle; D002951:Citrates / Q000378:metabolism; D005943:Gluconeogenesis; D005954:Glucosephosphate Dehydrogenase / Q000032:analysis; D066298:In Vitro Techniques; D007773:Lactates / Q000378:metabolism; D008055:Lipids / Q000096:biosynthesis*; D008099:Liver / Q000201:enzymology*; D008190:Lyases / Q000032:analysis; D008291:Malate Dehydrogenase / Q000032:analysis; D011422:Propionates / Q000378:metabolism; D012417:Rumen / Q000201:enzymology*; D014461:Ultracentrifugation
D002951:Citrates; D007773:Lactates; D008055:Lipids; D011422:Propionates; D008291:Malate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D008190:Lyases; D002262:Carboxy-Lyases