Brain capillary guanosine triphosphatase: a distinction from adenosine triphosphatase

Differences in kinetic properties, pH response, sensitivity to ouabain, and disc-acrylamide electrophoresis resolution, are observed when GTP and ATP are used as the substrates for triphosphohydrolases in isolated rat brain microvessels. In brain parenchyma there are no such differences. It is concluded that substrate-specific GTPase exists in brain microvessels.