Influence of pyridoxal-5'-phosphate on the determination of the alanine aminotransferase and aspartate aminotransferase of commercial test sera.

The influence of pyridoxal-5'-phosphate on the activities of alanine aminotransferase and aspartate aminotransferase from commercial test sera was investigated. Enhancement of the activity of alanine aminotransferase by the coenzyme is about 20% when 0.1 mmol/1 of pyridoxal-S'-phosphate is added to the reaction medium. This concentration seems sufficient for full saturation of the apoenzyme. For aspartate aminotransferase, the enhancement of the enzymatic activity is much higher than for alanine aminotransferase and 0.1 mmol/1 of coenzyme is not sufficient for full saturation in this case.