Degradation of somatomedin A by various organ homogenates from rats.
Degradative activities of somatomedin A (SMA) have been examined in various tissue homogenates of rat using trichloracetic acid precipitable radioactivity of 125I-SMA. Kidney and testis showed higher specific activities and liver and brain lower activities. They were dependent on SH reagents; 0.5 mM HgCl2 inhibited the degradative activity of liver completely and 1 mM dithiothreitol (DTT) augmented the activity slightly. The activities in liver were separated by differential centrifugation; about 90 per cent of the total activity in the whole homogenate was recovered in the supernatant fraction at 100,00 x g for 60 min, and 10 per cent in the precipitate. The pH profile of each fraction was different; that of the supernatant showed a single peak at pH 7.4 and that of the pellet revealed two peaks at pH 5.9 and 7.4. However, both fractions showed similar SH-dependency.
D000818:Animals; D007457:Iodine Radioisotopes; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008168:Lung / Q000378:metabolism; D008297:Male; D011869:Radioligand Assay; D051381:Rats; D013002:Somatomedins / Q000378:metabolism*
D007457:Iodine Radioisotopes; D013002:Somatomedins