モルモット小腸平滑筋の細胞膜に富む画分の分離と指標酵素活性

抄録

By means of a preparation technique based on the discontinuous sucrose density gradient, subcellular fractions were isolated from guinea pig intestinal smooth muscle cells.
A fraction which distributed to a 33% sucrose layer showed relatively high activities of 5'-nucleotidase, Na⁺·K⁺-ATPase and ouabain sensitive Na⁺·K⁺-ATPase. The fraction had a low NaN3 sensitive Mg²⁺-ATPase activity. On the other hand, the high activity of glucose-6-phosphatase showed a broad distribution. Though the sucrose density gradient proceeded over a series of fine layers, cross-contamination of microsome into the 33% sucrose fraction was not reduced. To reduce microsomal cross-contamination, another procedure was employed. The homogenization time of 77000×g sediment to be layered on the top of the sucrose density gradients was prolonged. This procedure did not change the distribution of K⁺ activated p-nitrophenylphosphatase, K⁺ activated ouabain sensitive p-nitrophenylphosphatase and ouabain sensitive Na⁺. K⁺-ATPase activities. The peak of NADH cytochrome c reductase activity was shifted to a 38% sucrose fraction from a 33% sucrose fraction and the activity of this marker enzyme in the 33% sucrose fraction decreased to 60% of that of the prior procedure.