In:
Biochemistry and Cell Biology, Canadian Science Publishing, Vol. 66, No. 10 ( 1988-10-01), p. 1023-1031
Abstract:
The millimolar Ca 2+ -requiring form of the Ca 2+ -dependent proteinase from chicken breast skeletal muscle contains two subunit polypeptides of 80 and 28 kDa, just as the analogous forms of this proteinase from other tissues do. Incubation with Ca 2+ at pH 7.5 causes rapid autolysis of the 80-kDa polypeptide to 77 kDa and of the 28-kDa polypeptide to 18 kDa. Autolysis of the 28-kDa polypeptide is slightly faster than autolysis of the 80-kDa polypeptide and is 90–95% complete after 10 s at 0 °C. Autolysis for 15 s at 0 °C converts the proteinase from a form requiring 250–300 μM Ca 2+ to one requiring 9–10 μM Ca 2+ for half-maximal activity, without changing its specific activity. The autolyzed proteinase has a slightly lower pH optimum (7.7 vs. 8.1) than the unautolyzed proteinase. The autolyzed proteinase is not detected in tissue extracts made immedately after death; therefore, the millimolar Ca 2+ -requiring proteinase is largely, if not entirely, in the unautolyzed form in situ.
Type of Medium:
Online Resource
ISSN:
0829-8211
,
1208-6002
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
1988
SSG:
12
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