|Proteins in fish muscle|
Jebsen, J.W. (1962). Proteins in fish muscle, in: Heen, E. et al. Fish in nutrition. pp. 68-72
In: Heen, E.; Kreuzer, R. (1962). Fish in nutrition. Fishing News (Books): London. XXIII, 447 pp., more
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VLIZ: Biological Resources 
(1) The proteins of muscle fibrines, tropomyosin, actin, myosin and actomyosin: 65 per cent of fish muscle protein (40% in mammals). (2) The proteins of cytoplasma (enzymes in muscle metabolism), globulin x, myogen, myoglobin: 26-30 % of fish muscle protein (35-40 per cent in mammals). (3) The proteins of the connective tissue, stromaproteins (collagen): 3 % of the muscle of teleost; 10% in elasmobranch (17 per cent in mammals). Group 1: extractable with neutral salt solution of high ionic strength >= 0.5. Group 2: extractable with neutral salt solution of low ionic strength <= 0.15. Group 3: not extractable with neutral salt solution, nor in diluted acids and alkalies. Group 1 has great crystal lattice energy and great dipole moment; this results in great sensitivity towards salt ionesGroup 2 is rich in charged side chains, but has a small dipole moment; this results in a lower sensitivity towards salt iones. Precipitation of fish proteins: percentage saturation of ammonium sulphate. Tropomyosin: 50-66 Myosin: 35-48Actin: 10-20Actomyosin: 28-38 Result of electrophoresis:Both pure actomyosin and pure actin give one sharp peak. Pure myosin gives a broader peak; this may indicate some heterogeneity. Myogen gives 7 components by Tiselius-electrophoresis. Each species of fishes gives a different pattern. Electrophoresis in starchgel gives 12 components at pH 7.5.Results by ultracentrifuge:Both actomyosin and tropomyosin give one sharp peak. Myosin is not homogeneous. Myogen gives four componements.Crystallized fish protein:Myogen proteins, myoglobin and tropomyosin. In the white muscle, glycogenic metabolism predominates; in the red muscle (Musculus lateralis superficialis trunci) the citric acid cycle probably prevails. The red muscle (e.g. in tuna) seems to be a passive muscle with a high oxygen metabolism. The white muscle is an active muscle with low oxygen supply.