Isolation and characteristics of a porcine muscle cysteine proteinase inhibitory fraction

Abstract

Proteolysis regulation is a key factor in meat manufacturing processes. Cysteine proteinases ‐ calpains and cathepsins B and L ‐ are involved in postmortem muscle proteolysis, the cathepsins having most importance in meat products. Thus, the interest in the study of their physiological inhibitors ‐ cystatins ‐ has recently increased. The isolation of a cysteine proteinase inhibitory fraction from longissimus porcine muscle has been achieved using an S‐carboxymethylated‐papain‐Sepharose gel and recovering the inhibitors by elution with 50 mM trisodium phosphate buffer, pH 11.5, 0.5 M NaCl. The cystatin fraction showed good resistance to temperature, pH and reducing agents and consisted of a mixture of proteins of approximate molecular weights ranging from 15 to 95 kDa (SDS‐PAGE electrophoresis). This study is a preliminary approach to analyse the possibilities of using porcine inhibitors as additives in meat industry.