Effect of low voltage electrical stimulation on changes in proteome of bovine longissimus muscle during postmortem aging

摘要

The objective was to determine the effect of postmortem electrical stimulation (ES) on changes in insoluble and soluble protein fractions of bovine longissimus dorsi muscle (LD). Eight steers (498 kg) were harvested; carcasses were split. One side was a control (NS) and the other was ES (100 V, 60 Hz for 1 minute). Proteins from each muscle were separated into soluble (low ionic strength buffer) and insoluble fractions. The effect of ES on muscle protein profile was evaluated with 2D difference in gel electrophoresis using a pH 3-10 or pH 4-7 gradient in the first dimension and a 12.5 % acrylamide SDS-PAGE gel in the second dimension. ES resulted in an accelerated pH decline of LD during the 24 h postmortem chilling period. ES had an apparent effect on protein solubility; fructose-bisphosphate aldolase A, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase 1, pyruvate kinase isozyme Ml were all less soluble in response to ES. However, annexin, pyruvate dehydrogenase and creatine kinase were all more abundant in the soluble fraction in response to ES. At 1 d postmortem, ES had a notable affect on the abundance of two isoforms of myosin light chain 2 (MLC2). In the insoluble fraction, one MLC2 spot increased while a separate MLC2 spot decreased in response to ES. Results demonstrate a clear effect on the apparent solubility of proteins. These trends may be useful indicators of postmortem metabolism in beef.