Roche, MPattabiraman, T N1992-04-012009-05-271992-04-012009-05-271992-04-01Roche M, Pattabiraman TN. Further studies on proteinases and alpha 2-macroglobulin activity in diabetic plasma. Indian Journal of Biochemistry & Biophysics. 1992 Apr; 29(2): 189-91http://imsear.searo.who.int/handle/123456789/26254Loss of chymotrypsin binding capacity of alpha 2-macroglobulin in diabetic plasma on in vitro incubation, could be partially prevented by phenylmethyl sulphonyl fluoride and pepstatin A. Prior ten-fold dilution of plasma with 0.02 M phosphate buffer (pH 7.0) completely arrested the process. The phenomenon could not be reactivated by Ca2+, lecithin or bovine serum albumin. Diabetic plasma, like normal plasma, exhibited maximal hydrolytic activities on H-D-Pro-Phe-Arg-p-nitroanilide, H-D-Val-Leu-Arg-p-nitroanilide and H-D-Ile-Pro-Arg-p-nitroanilide. The hydrolytic activities were not significantly diminished on incubation of plasma at 37 degrees C for 12 hr, unlike alpha 2-macroglobulin activity. On gel chromatography on Sephadex G-200, part of the proteolytic activity in diabetic plasma coeluted with alpha 2-macroglobulin in the VO region. A second activity peak (absent in normal plasma) was eluted with a Ve/V0 value of 1.40. Possible role of free proteinases in diabetic plasma in the inactivation of alpha 2-macroglobulin is discussed.engAmino Acid SequenceChymotrypsin --metabolismDiabetes Mellitus --bloodEndopeptidases --bloodHumansMolecular Sequence DataOligopeptidesProtease Inhibitors --pharmacologySubstrate Specificityalpha-Macroglobulins --metabolismJournal Article