Nutritional effects on the calpain system in skeletal muscle of sheep

B.C. Thomson, V.H. Oddy, R.D. Sainz

School of Agriculture and Forestry, University of Melbourne, Parkville, Victoria 3052, Australia

Proceedings of the New Zealand Society of Animal Production. 1992, 52: 101-102

The calpain system consists of two enzymes and their endogenous inhibitor, calpastatin, and is involved in the breakdown of myofibrillar protein in skeletal muscle. We have investigated the relationship between the calpain system and protein degradation in sheep under three different feeding regimes. Calpain were separated from fresh muscle using a DEAE-Sephacel ion exchange column. Calpain I and calpastatin activities were higher in the restricted group than in the ad- libitum group. Fasting increased calpastatin but had no effect on the calpain I activity. There was a positive relationship between the calpastatin : calpain I ratio and protein degradation and a negative relationship with calpain I. This result is at variance with the idea that calpain I activity limits the rate of protein degradation.

Keywords: NZSAPAB; Calpain; nutrition; protein degradation; calpastatin

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