Human deficiencies of vitamin B6. I. Studies on parameters of the assay of the glutamic oxaloacetic transaminase by the CAS principle.

Human deficiencies of vitamin B6 may be detected and accurately measured by a dual enzymic assay which is based on the CAS principle, i.e., the unsaturation and saturation of the coenzyme (pyridoxal 5'-phosphate) of a Coenzyme - Apoenzyme System. Glutamic oxaloacetic transaminase (GOT) is excellent for this assay. Two control groups (24 athletes and 25 students) showed deficiencies of GOT activity of 11+/-6% and 12+/-7%, respectively, which are negligible and which may be compared with analogous data from disease states. Contrary to a previous report, GOT activities must be determined within one day of preparation of the enzyme for meaningful assays. Frozen storage of erythrocyte hemolysates up to 21 days showed increasing apparent dissociation of pyridoxal 5'-phosphate from the coenzyme - apoenzyme system corresponding to increasing false deficiency levels. Dilution of the hemolysates and frozen storage augmented the apparent dissociation and false levels. This dual GOT assay is effective to detect and measure human deficiencies of vitamin B6.