Enolase activity and isoenzyme distribution in human brain regions and tumors

The distribution of enolase (EC 4.2.1.11) activity and isoenzymes in various regions of human brain at different ages (from 23 weeks of gestation to 95 years) and in brain tumors has been determined. Total enolase activity increased in all regions with age. No significant differences were found in the relative proportions of alpha alpha-, alpha gamma, and gamma gamma-enolase isoenzymes in the various brain regions, determined by agarose gel electrophoresis. Type alpha alpha-enolase was the predominant isoenzyme, and alpha gamma-enolase represented a substantial proportion of the total enolase activity. Astrocytomas, anaplastic astrocytomas, glioblastomas, and meningiomas possessed lower enolase activity than normal brain. Among astrocytic tumors, total enolase activity correlated with malignancy. Astrocytomas possessed the lowest and glioblastomas the highest enolase activity. All tumors possessed a higher proportion of alpha alpha-enolase and a lower proportion of gamma gamma-enolase than the normal human brain. Among astrocytic tumors, glioblastomas were the tumors with the highest proportion of alpha alpha-enolase and lowest proportion of gamma gamma-enolase.