抄録
Degradative activities of somatomedin A (SMA) have been examined in various tissue homogenates of rats using trichloracetic acid precipitable radioactivity of125ISMA. Kidney and testis showed higher specific activities and liver and brain lower activities. They were dependent on SH reagents; 0.5mM HgCl2 inhibited the degradative activity of liver completely and1mM dithiothreitol (DTT) augmented the activity slightly. The activities in liver were separated by differential centrifugation; about 90per cent of the total activity in the whole homogenate was recovered in the supernatant fraction at 100, 000×g for60min, and 10per cent in the precipitate. The pH profile of each fraction was different; that of the supernatant showed a single peak at pH7.4and that of the pellet revealed two peaks at pH5.9 and 7.4. However, both fractions showed similar SH-dependency.
