Presence of ubiquitin in bovine post-mortem cardiac muscle

We prepared sarcoplasmic proteins from bovine cardiac muscle immediately af ter slaughter (1.0 h; 0 days) and from stored muscle at 1, 2 and 7 days pos t-mortem for SDS-PAGE and Western blotting analysis. Characterization of th e ubiquitin antiserum (Sigma, St Louis) showed clear and strong recognition of the ubiquitin band (8.6 kDa) and another minor band (17 kDa) in the pur ified ubiquitin sample (Sigma, St Louis). Among the sarcoplasmic proteins p repared from stored muscle at 0 and 7 days, this antiserum also reacted wit h bands corresponding to purified ubiquitin and small amounts of some other , higher-molecular-mass proteins (about 25 and 30 kDa) which were considere d to be ubiquitin-protein conjugates. However, the 25 kDa band was faint in the 7 days sample, suggesting that it had degraded. We compared these resu lts with those from oar previous study of bovine skeletal muscles, in which both ubiquitin and the ubiquitin-protein conjugates had almost disappeared in the samples tested at 10 days post mortem. (C) 2000 Elsevier Science Lt d. All rights reserved.