Breakdown of large proteoglycans in bovine intramuscular connective tissue early postmortem

Summary

In the present study, a decomposition of intramuscular connective tissue in beef early postmortem was demonstrated by comparing samples from M. longissimus dorsi (LD) collected immediately after slaughter and after 24 h and 48 h storage by histological and biochemical methods. The histological study showed a widening of the endomysial sheaths after storage. For fractionation of proteoglycans, extraction in 4M guanidine-HCl added protease inhibitors, CsCl, gradient ultracentrifugation and gel chromatography were used. Gel chromatography demonstrated that the proteoglycan preparation was broken into fragments of lower molecular weight. Cellulose acetate electrophoresis and dot blot analysis identified the components involved as hyaluronic acid (HA) and a large proteoglycan (PGL) immunologically related to aggrecan from sclera. SDS polyacrylamide gel electrophoresis (SDS-PAGE) confirmed depolymerization of the high molecular weight components, and a large component of molecular weight above 220 KDa with glycosaminoglycan (GAG) staining properties was not visible in the gel after storage.