Properties of purified tyrosine aminotransferase from adult and senescent rat liver.

Induced tyrosine aminotransferase from adult and old rat liver was purified and its properties were studied. No differences could be detected for any physicochemical properties studied, i.e. specific activity, molecular weight, isoelectric point, thermostability, sensitivity to trypsin, Km for pyridoxal phosphate. Moreover, some age-related modifications previously described such as increased sensitivity to trypsin for induced old enzyme were no longer found. Tyrosine aminotransferase provides another argument against the 'error theory' of cellular aging.