A Study of the Sarcoplasmic Proteins of Porcine Muscle by Starch Gel Electrophoresis

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Abstract
SUMMARY– Extensive investigations were conducted on numerous variables in order to establish the most ideal conditions for the starch gel electrophoresis of the proteins of porcine skeletal muscle sarcoplasm. This technique was used to evaluate the characteristics of the sarcoplasm extracted from (a) muscles at various times post‐mortem, (b) muscles which ultimately remained normal in color and gross morphology as well as muscles which became extremely PSE and (c) muscles which had altered color and gross morphology due to post mortem treatment (i.e., normal color and gross morphology due to surface treatment with L‐N2 and PSE characteristics due to post‐mortem incubation at 37°C for 4 hr).There were no discernible differences between the starch gel electrophoretograms of sarcoplasmic proteins extracted from pre‐ and post‐rigor muscle. Likewise, there were no visually detectable differences between the starch gel electrophoretograms of sarcoplasmic proteins extracted from naturally occurring normal and PSE muscles. Furthermore, the preservation of normal color and gross morphology through L‐N, treatment did not give rise to electrophoretic differences when compared with either naturally occurring normal or PSE muscle.Although sarcoplasmic protein solubility diminished in naturally occurring PSE muscle, this loss in soluble protein did not necessarily manifest itself in the preferential denaturation of a specific sarcoplasmic protein. However when muscles were incubated at 37°C for 4 hr to induce the PSE condition they yielded sarcoplasmic extracts with marked electrophoretic reductions in creatine kinase, phosphoglucomutase, triosephosphate isomerase and F‐protein (Scopes, 1965). Although there were no apparent differences in creatine kinase isozymes between samples of muscle which ultimately remained normal or became PSE, the minor (fastest moving) creatine kinase band, as well as the phosphoglucomutase bands, appeared more labile during incubation at 37°C than the major (slowest moving) creatine kinase band.