Fish proteins amino acid composition

Legume forages, such as alfalfa or clover, are considered high quaHty, readily available protein sources. Animal sources of supplemental protein include meat and bone meal blood meal, 80% CP fish meal other marine products and hydroly2ed feathermeal, 85—90% CP. Additionally, synthetic amino acids are available commercially. Several sources (3,9,19) provide information about the protein or amino acid composition of feedstuffs. 

Discarded fish bones and cutoffs may contain considerable amounts of muscle proteins. These muscle proteins are nutritionally valuable and easily digestible with well-balanced amino acid composition (Venugopal et al., 1996). Therefore, fish proteins derived from seafood processing by-products can be hydrolyzed enzymatically to recover protein. Protein hydrolysates from several marine species have been analyzed for their nutritional and functional properties, and researches have mainly explored the possibility of obtaining biologically active peptides (Benkajul and Morrissey, 1997). Moreover, skipjack tuna muscle (Kohama et al., 1988), sardine muscle (Bougatef et al., 2008), and shark meat (Wu et al., 2008) have been used to separate potential peptides. 

Although proteins and amino acids in the food influence the metabolism of the fish, they do not alter the amino acid composition of proteins in the body. In contrast, the lipids in the body of the fish are greatly influenced by the dietary lipids. In particular, it is the triacyl-glycerols (the main constituents of reserve energy) which are influenced by diet (Lovem, 1937,1942,1964 Kelly et al., 1958 Brockerhoff et al., 1963, 1964 Ackman, 1964, 1967 Ananyev, 1965 Ackman and Eaton, 1966, 1976). Food lipids also influence the structural lipids of the fish. 

Gur yanova, S. D. (1977). [The amino-acid composition of the total proteins of plerocercoids of the genus Diphyllobothrium and their hosts.] In Russian. In [Comparative biochemistry of fish and their helminths. Lipids, enzymes, proteins. (Collected uwfcy).] ed. V. S. 

The study of fish proteins were initiated by the Swiss physiologist Miescher (1897), who first isolated the protamines from the sperm cells of various fishes as early as 1868. The relatively simple amino acid composition of these proteins and their pharmacological action have since promoted extensive researches, first of aU by Kossel and co-workers, whose important... 

Solubilization of Protein. Fish protein concentrate has high nutritional quality as determined both from its essential amino acid composition and from animal feeding experiments. Unfortunately, the concentrate is quite insoluble in water because of its denaturation by the solvent extraction method used in processing thus it contributes no functional properties to a food and must be used in bakery products primarily. A potentially useful method of solubilizing the protein is by proteolysis (9-12). As is the case with protein hydrolysates of casein and soybean protein, bitter peptides are formed during the hydrolysis. Papain and ficin produce more of these bitter peptides than does Pronase, for example (12). Pronase was found to produce a more brothy taste (13). A possible method of removing the bitter peptides is to convert the concentrated protein hydrolysate to plastein by further proteolytic enzyme action (14) to remove the bitter peptides. 

Table VI. Amino Acid Compositions of Low-Phenylalanine High-Tyrosine Plasteins from Soybean and Fish Proteins (wt %)...

Y., 1965, Constituents of the extracts and amino acid composition of the protein of short-necked clam. Bull. Jpn. Soc. Sci. Fish.,... 

Table 1.44. Amino acid composition (weight-%) of plasteins with high tyrosine and low phenylalanine contents from fish protein concentrate (FPC) and soya protein isolate (SPI)...

The protein-N content of fish muscle tissue is between 2-3%. The amino acid composition, when compared to that of beef or milk casein (Table 13.6), reveals the high nutritional value of fish proteins. The sarcoplasma protein accounts for 20-30% of the muscle tissue total protein. The contractile apparatus accounts for 65-75% protein the connective tissue of teleosts is 3% and of elasmobranchs, such as sharks and rays (skate or rocker), is up to 10%. The individual protein groups and their functions in muscle tissue of mammals (cf. 12.3.2) also apply to fish. 

The amino acid composition shows relatively high amounts of Arg (12%) and Lys (9%) and little Pro. The paramyosin molecule consists of two peptide chains (M ) 95,000-125,000), each of which is 120 nm long, has a helical structure and is twisted to a rod. In fact, two disulfide bonds contribute to the stability of the molecule. It forms the core in the thick filaments and is surrounded by myosin. In the production of gels, it influences the rheological properties and is the reason why gels made from mollusk meat are more elastic and more cohesive than gels made from fish protein. 

For fish, proteinogenic amino acids (AAs) are commonly divided into 10 essential (Arg, His, lie, Len, Lys, Met, Phe, Thr, Trp and Val) and 10 non-essential AAs (NRC, 1993). The aim of the study was to test whether the dietary non-essential amino acid (NEAA) composition has an effect on growth, protein utilisation and of AAs in rainbow trout (Oncorhynchus mykiss). In addition, it... 

Fish sperm contain nucleoprotamines. Upon treatment with sulfuric acid, the nucleoprotamines are reduced to nucleic acid and protamine sulfate. The chemically heterogeneous protamines of molar mass 2000-8000 thus obtained contain only a few different kinds of amino acid residues per molecule. They are relatively rich in basic amino acids, as the composition of the protamines clupeine and salmine shows (Table 29-6), and never contain cystine, aspartic acid, or tryptophan. The basic amino acids are responsible for the bonding of the protein to the nucleic acid component. 

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