Degradation of insulin by a particulate fraction from adipose tissue.
The destruction of (125)I-labelled insulin by an enzyme system from rat adipose tissue was studied. The system was located in the particulate fraction. Activity was assayed by the amount of (125)I-labelled degradation products rendered soluble in trichloroacetic acid. The system was heat-labile, with an alkaline pH optimum. The velocity of the reaction varied directly with the enzyme concentration. Paper chromatography of the degradation products showed six ninhydrin-sensitive areas with radioactivity coinciding with three of them. Albumin inhibited the system; ribonuclease did not. Although only 25% of the total (125)I-label was detected by this assay, results with insulin-specific assays suggested that most (80-90%) of the hormone was inactivated. Possible interpretations of these results are discussed. The particulate fractions of other tissues were also studied.
D000273:Adipose Tissue / Q000201:enzymology* / Q000378:metabolism; D000418:Albumins; D000818:Animals; D002854:Chromatography, Paper; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000378:metabolism*; D007456:Iodine Isotopes; D007668:Kidney / Q000201:enzymology; D008297:Male; D009206:Myocardium / Q000201:enzymology; D051381:Rats; D012260:Ribonucleases; D014238:Trichloroacetic Acid
D000418:Albumins; D007328:Insulin; D007456:Iodine Isotopes; D014238:Trichloroacetic Acid; D012260:Ribonucleases