[Aspartate aminotransferase activity as dependent on the degree of serum dilution]

Dependence of the enzymatic reaction rate V. catalyzed by aspartate aminotransferase, on concentration of standard human blood serum Moni-trol I ("Dade", Switzerland) was studied. In the range of moderate dilutions, which did not exceed 1.3-times, the V value altered in accordance with the blood serum concentration C. Under conditions of extensive dilutions dependence of V on blood serum concentration became complicated. The non-linear type of V dependence on blood serum concentration appears to be due to deaggregation of the enzyme molecules with formation of more active fragments as a result of blood serum dilution. Two parameters should be used for characteristics of blood serum aspartate aminotransferase activity: the enzymatic activity of undiluted blood serum as well as the ratio between specific activities of the enzyme in an associated from and the products of its dissociation, i.e. when C-1 and C-0, respectively.