Variation of Proteins in Myofibrils and Connective Tissue of Chicken Red and White Skeletal Muscles Influenced by Under-nutrition

Abstract

The influence of under-nutrition (sub-maintenance feeding) and ad libitum feeding on myofibrillar and connective tissue (collagen-like) proteins of red (leg) and white (breast) muscle of growing broilers was studied. The content of 0.3 m KCl-extractable myofibrillar proteins was lower, and that of 6 m guanidine-HCl- and 1% Triton X-100-soluble proteins and connective tissue proteins was higher in red than in white muscle of ad libitum fed broilers. The relative amount of some specific proteins in 0.3 M KCl-, 0.6 m KI-, and Triton X-100-extracts differed by more than 20 to 50% between red and white muscle. Under-nutrition caused some decrease in KCl-extractable proteins of red muscle, and an increase in the connective tissue content of red muscle and in KI-, guanidine-HCl-extractable proteins, and connective tissue of white muscle. SDS-polyacrylamide gel electrophoretograms of 0.3 m KCl extracts showed that the relative concentration of 95 K protein (α-actinin) in both muscles and 59 K protein in red muscle from underfed broilers was lower than that from controls, whereas the relative content of 200 K (myosin heavy chain), 160 K, and 43 K (actin) proteins was rather high in both muscles from underfed broilers. Noticeable changes in the levels of some amino acids of connective tissue were also observed in red and white muscle as a result of under-nutrition.