The muscle of carp was fractionated into water-soluble, alkali-soluble (0.1_N NaOH), acid-soluble (0.5M acetic acid), hot water-soluble (extraction with water at 120°C for 1h), and residual fractions. The analyses of amino acid and SDS-polyacrylamide gel electrophoresis showed that collagen in the muscle was quantitatively recovered only in the acid-soluble and hot water-soluble fractions and non-collagenous proteins were absent in these fractions. On the basis of the colori-metric determination of protein in these fractions, we devised a simplified method for determinating the soluble and insoluble collagens in the muscle.
The soluble and insoluble collagens in the muscles of the rainbow trout Salmo gairdnerii, Japanese mackerel Scomber japonicus, carp Cyprinus carpio, and eel Anguilla japonica were deter-mined by the proposed method. The total collagen contents in the muscles of rainbow trout, Japanese mackerel, carp, and eel were found to be 0.47, 0.50, 0.60, and 1.99% of the wet muscle, respectively.