BINDING OF COBAMIDES TO ETHANOLAMINE DEAMINASE

The binding to ethanolamine deaminase of two cobalamin derivatives, 5′-deoxyadenosylcobalamin and hydroxocobalamin, was investigated by kinetic studies and circular dichroism spectroscopy. A change in the circular dichroism spectrum was found to accompany the binding of either of these derivatives to the enzyme. By following the change in the spectrum as a function of the amount of derivative added, it was found that one molecule of enzyme would bind two molecules of cobalamin. This result was confirmed by the kinetic studies, which showed in addition that each molecule of cobalamin was associated with a separate active site. It was further shown that the two active sites do not interact, but appear to function entirely independently. © 1969, American Chemical Society. All rights reserved.