Calcium-activated neutral proteinases (CANPs) and their endogenous specific inhibitor calpastatin are found in a wide variety of vertebrate and invertebrate tissues. The CANPs are cysteine proteinases that have an absolute requirement for Ca2+ for activity. μ-Calpain and calpastatin were purified by successive chromatographic steps on Toyopearl-Super Q 650S and Pharmacia Mono Q HR 5/5 columns. The enzyme has a Mr of 84KDa using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), a Mmin of 79KDa from amino acid analysis and an pI of 5.2. Calpastatin has a Mr of 323KDa using denaturing gradient PAGE and a pI of 4.7. The amino acid composition of μ-calpain revealed 689 residues and the pH and temperature optima were found to be 7.5 and 37°C, respectively. μ-Calpain underwent a Ca2+-dependent autoproteolysis producing a fragment of 82KDa. The N-terminal sequence of μ-calpain showed 24 and 18% sequence identity with human and bovine μ-calpain.
|Number of pages||12|
|Journal||International Journal of Biochemistry and Cell Biology|
|Publication status||Published - 2002 Apr 13|
ASJC Scopus subject areas
- Cell Biology