Fish, amino acid content

The molecular weight of 320,000 obtained for the muscle enzyme from sedimentation-diffusion data at 2-6 mg/ml and v = 0.75 (132) is to be compared with 270,000 obtained by Wolfenden et al. from s20,w = 11.1 S and D2 ,w = 3.75 X 10 7 cm2 sec1, and v = 0.731 calculated from the amino acid content (92). The rabbit muscle enzyme has a normal amino acid content, that is, no unusually low or large amount of a particular amino acid was found. Of the 32 cysteine/half-cystine residues per mole based on a molecular weight of 270,000, 6.2 were rapidly titrated with p-mercuribenzoate (92). Typical protein absorption spectra were reported for elasmobranch fish (126), carp (125), rat (127), and rabbit muscle enzyme (68). An E m at 280 nm = 9.13 has been reported for the rabbit muscle enzyme (133). The atypical absorption spectrum with a maximum at 275-276 nm observed by Lee (132) is indicative of contaminating bound nucleotides. 

Vladimirov, V.I. (1974). Dependence of the quality of carp embryos and larvae on female age, amino acid content of eggs and the introduction of amino acid additives to water at early developmental stages (In Russian). In Different Quality of Early Ontogenesis of Fish (V.I. Vladimirov, ed.), pp. 227-254, Naukova Dumka, Kiev. 

Thorsen, A. and H.J. Fyhn. Final oocyte maturation in vivo and in vitro in marine fishes with pelagic eggs yolk protein hydrolysis and free amino acid content. J. Fish. Biol. 48 1195-1209, 1996. 

Table 2.9 Amino acid content of meat, chicken and fish (in g per 16g of nitrogen). ...

The structures of bacteria are extremely complex. Nitrogen in particular is distributed in many types of chemical structures, including proteins (amino acids), peptides, nucleic acids, and amino sugars [3, 4]. The amino acid content of bacteria is the best indicator of the overall nutritional utility to animals and humans. Component analyses and the amino acid content of methanol SCP, fish meal, soybean meal, and nonfat dried milk (NFDM) are listed in Tables 1 and 2, respectively [4, 10]. The protein content of methanol SCP is about 80%, which is much hi er than that of the other types of food meals. Furthermore, the overall quality of methanol SCP is very od. As a result, it has often been sold at a premium over alternative protein sources. 

In spite of some differences in the species of fish used and the methods employed, the fractions designated i, ii, and iii in Table VII-1 correspond to one another as regards their amino-acid content. However, there are differences in the N-terminal residues. Fraction iii, which has the simplest amino acid composition with N-terminal alanine, was the first to be purified and have its complete amino-acid sequence elucidated (Ando et aL, 1962). New methods for the fractionation of clupeine have recently been developed and are described below (this chapter. Section B). 

Fresh potatoes may contain 0.5-1.2% (d.b.) of pure protein in the dissolved state. It makes up about 50% of the entire N-substance. The amino acid content is - in contrast to most plant proteins -highly balanced as to its physiological value for human and animal nutrition (such as egg or fish protein). To utilize this valuable product, as well as for environmental reasons, p. is isolated as a byproduct of - potato starch production. 

Myosin. Rabbit muscle myosin is a long, thin molecule (VI400 X 20-50 A) with a molecular weight of 5 X 10. It is composed of two heavy chains and four light chains as demonstrated by SDS-polyacrylamide disc gel electrophoresis. On tryptic digestion, myosin is split into the subunits, H-meromyosin (HMM) and L-mero-myosin (LMM). HMM is further split into S-l and S-2 subunits. While LMM is a rod of V)0% a-helical content, the a-helical content for HMM, S-l and S-2 fragments is 46%, 33% and 87%, respectively. The ATPase activity is localized in the S-l subunit (33,34). Although fish myosins appear to have the same structural profile (10,22,35-40) and similar amino acid composition as rabbit myosin (39,41,42), fish myosin is different from rabbit myosin in physicochemical properties such as solubility, viscosity and stability (10,22,35-40). 

Table VII shows the content of basic amino acids in a number of edible invertebrates. The content of aromatic amino acids from a wide variety of marine species and terrestrial animals shows little variation. Furthermore, the yield of cystine and of methionine is essentially the same whether terrestrial animals, fish, or marine invertebrates are the source of protein. Crab and shrimp meal are very rich in protein. Crab meal contains at least 25% protein, shrimp meal over 40% (Yearbook of Agriculture, 1939).

Table VIII shows the average values for amino acids in fish proteins. Block and Bolling (1945) emphasize the fact that muscle proteins from a wide variety of species show little if any significant differences in their content of aromatic amino acids. . . the relative constancy in the basic amino acids in all types of muscle, animal, fish, or crustacean, is noteworthy. The authors use crustacean as synonymous with shellfish. Hence, their generalizations are meant to include oysters and clams.

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