530 



U. S. BUREAU OF FISHERIES 



AMINO ACID ANALYSES 



The methods of determining the several amino acids obtained 

 by the hydrolysis of proteins while not especially accurate are fairly 

 well standardized, and on this account different workers can check 

 each other with a fair degree of accuracy. Unfortunately, compara- 

 tively few fish have been analyzed for theii' amino acid content. In 

 Table 20 are given the amounts of amino acids obtained upon the 

 hydrolj^sis of 100 grams of ash and moisture-free muscle protein of 

 those that have been analyzed, viz, porgy, halibut, bonito, cod, 

 whale, and scallops. The analyses of the proteins of chicken and 

 beef are given for comparision. 



Table 20. — Cleavage prodticts of proteins of various fish and shellfish and some 



meats 



[Expressed in grams obtained from 100 grams of ash and moisture-free muscle protein] 



Product 



Glycine 



Alanine.- 



Valine. 



Leucine 



Proline 



Phenylalanine 

 Aspartic acid.. 

 Glutamic acid. 



Serine 



Tyrosine 



Arginine 



Histidine 



Lysine... 



Ammonia 



Tryptophane. 



Guanine 



Adenine 



Hypoxanthine 



Porgy 

 (Pagrus 

 major) 



iQ.O 

 1.04 

 2.77 

 8.82 

 1.22 

 4.72 

 1.66 

 1.63 

 (2) 

 2.64 

 5.15 

 2.07 

 6.28 

 1.32 

 0) 

 (2) 

 (2) 



I Bonito (Katsu- 

 Halibutj wonus pelamis) 

 (Hippo-| 



glossus 



rioSi Light Dark 



glossus) gg^jj gpgjj 



0.0 

 e) 

 .79 



10.33 

 3.17 

 3.04 

 2.73 



10.13 

 (}) 

 2.39 

 6.34 

 2. 55 

 7.45 

 1.33 

 (') 



8 



0.0 



2.3 



2.8 



10.4 



3.1 



4.1 



3.3 



8.1 



Q) 



2.1 



7.8 



3.04 



7.41 

 .64 



(') 

 .09 

 .04 

 .08 



0.0 

 1.1 

 1.8 

 9.4 

 3.0 

 1.6 

 3.2 

 12.1 

 (^) 

 2.9 

 7.08 

 3.16 

 6.78 

 .78 

 (0 

 .12 

 .1 

 .03 



Cod 



(Gadus 



calla- 



orias) 



10.0 

 3.53 

 3.88 

 2.46 

 1.68 

 2.31 



.61 

 5.24 



.51 

 2.46 

 6.68 

 2.29 

 8.35 



.75 

 (?) 

 (}) 



Carp 

 (Cypri- 



nus 

 carpio) 



2.0 

 5.7 

 5.7 

 8.0 



10.5 



3.9 



.9 



12.9 



(?) 

 3.5 



14.0 



12.3 



11.3 

 1.4 



(') 



0) 



h 



C') 



Whale 



0.0 

 4.66 

 6.25 

 3.54 

 1.51 

 2.59 

 1.47 

 3.28 

 .49 

 2.40 

 6.48 

 3.44 



Scallop 



0.0 

 (?) 

 (?) 

 8.78 

 2.28 

 4.90 

 4.37 

 14.88 

 (2) 

 1.95 

 7.38 

 2.02 

 5.77 

 1.08 

 (') 

 (?) 

 C) 

 Q) 



Chick- 



0.68 

 2.28 

 (') 



11.19 

 4.74 

 3.53 

 3.21 



16.48 

 C-) 

 2.16 

 6. .50 

 2.47 

 7.94 

 1.67 



0) 



0) 



(') 

 (') 



Beef 



2.06 



3.72 



.81 



11.65 

 5.82 

 3.15 

 4.51 



15.49 



2.20 

 7.47 

 1.76 

 7.59 

 1.07 



(') 



C) 



0) 



(0 



'Or trace. 



■Present but not determined. 



• Not determined. 



Note.— Compiled from data published by Osborne and Heyl (1908), Okuda (1919), Okuda and Oyama 

 (1912-1916), Okuda, Okimoto, and Yada (1919), and Okuda and Matsuda (1923). 



These data indicate that the tyrosine, arginine, histidine, and 

 lysme content of various fishes is about the same, whereas the con- 

 tent of the various monoamino acids varies considerably. In general, 

 it may be said that the proportions of amino acids found in fish pro- 

 teins are approximately the same as those found in chicken muscle, 

 except that the proteins of fishes are curiously low in glycine, an 

 amino acid not essential in the diet. If the analysis of the proteins 

 of halibut muscle is compared with tliat of chicken proteins, it is seen 

 that the halibut proteins are much lower in the nonessential amino 

 acids, glycine, and valine and somewhat lower in proline, phenyla- 

 lanine, and glutamic acid, but that these proteins are almost identical 

 in their content of the essential amino acids, tyrosine, arginine, 

 histidine, and lysme. 



The analysis of the proteins of the porgy is curiously low in glu- 

 tamic acid, probably on account of an error in technique on the part 



