Interactions between Cystathionase and Aspartate Aminotransferase

The interaction of cystathionase with the apoprotein of the enzyme aspartate aminotransferase induces, concomitant with inhibition of cystathionase activity, an increase in aminotransferase activity. The interaction between both proteins brings about a change in the amplitude of the circular dichroic band corresponding to pyridoxal-5-P bound to the active center of cystathionase. These spectral changes, taken together with the results of enzymatic assays, clearly establish the transfer as occurring from cystathionase to the catalytic site of aspartate aminotransferase. Light-scattering measurements indicate that the enzyme cystathionase interacts with the apotransaminase to form large molecular weight aggregates.