Biochemical Differences between Red and White Muscle

Abstract

MYOGLOBIN, the principal pigment responsible for the red colour of muscle, was estimated by a method previously described by me¹. The activities of components of the cytochrome system were determined in enzyme preparations² made from the muscles. Cytochrome oxidase was measured by determining the rates of oxidation of neutralized ascorbic acid in the presence of known amounts of added cytochrome c and extrapolating to infinite cytochrome c concentration³ ; succinic oxidase by the rate of oxidation of sodium succinate in the presence of excess cytochrome c⁴; and succinic dehydrogenase by the rate of reduction of methylene blue in the presence of excess sodium succinate, using the Thunberg technique⁵. Energy-rich phosphate (∼ P), representing the sum of the labile phosphorus of adenosine triphosphate and of creatine phosphate, was determined as inorganic phosphate by Allen's method⁶, after controlled hydrolysis of muscle extracts.