160 J. AWAPARA 
One fact emerges clearly from most of the information reviewed: amino acids in 
their free state exist in much greater concentration in the tissues of invertebrates than 
in those of vertebrates. Comparison of organs from a lobster to those of a cat may 
have little meaning, but such a comparison will be shown in Table I to emphasize 
the enormous difference in composition. Invertebrates, as said before, have very 
large amounts of free amino acids in their tissues. The data in Table I were obtained 
from a papet by CAMIEN et al.’ who analyzed lobster tissue by microbiological methods 
and from a paper by TALLAN, MOORE AND STEIN? who analyzed cat organs by their 
TABLE I 
FREE AMINO ACID CONTENT OF TISSUES FROM THE CAT AND THE LOBSTER (Homarus vulgaris ) 
Values are expressed in mg/r1oo g wet wt. 




Lobster Cat 
Liver Muscle Kidney 
Amino acid Regular Dialyzed Unhydro- Extract Hydro- Extract Hydro- Extract Hydro- 
lyzed lyzed lvzed lyzed 
Glycine 1025 892 1025 9.1 54.0 6.7 17/2 14.4 36.0 
Proline 728 707 728 2.6 I Bez 8.5 4.0 5.3 
Arginine 778 830 778 0.2 Ib, D7 3.0 Hee? 1gyt 
Glutamicacid 267 267 44 66 241 36.2 150 137 174 
Alanine 133 133 133 16.5 16.9 24.7 24.3 20.7 19.4 
Aspartic acid 12 13 4.6 11.6 18.2 3.9 9.8 723 14.3 
Lysine 23 2 2 3.0 4.1 5.5 9.6 BaF) 9.1 
Threonine 8.6 8.1 9.1 Bill By) 3.9 4.0 3.0 4.1 
Valine 22 22 21 4.3 3.4 BER 2s 6.2 3.8 
Isoleucine — —- --- ie) 0.8 Te 1.6 2.3 7) 
Leucine 9.3 8.9 8.9 3.6 4.5 2.3 2.6 Be2 oy 
Histidine Fe], 8.3 9.7 9.1 13.4 3.6 103 27, 4.0 
Methionine II 17 12.0 0.9 0.4 ite 
Phenylalanine 5-4 5.0 5.2 1.8 2.5 1.0 1.6 1.6 ne / 
Tyrosine 1.6 1.8 i Bail r3 0.8 ie 1.8 ‘3 


ion-exchange method. Most amino acids are in higher concentration in the lobster 
muscle, but glycine is particularly abundant in the lobster as it is in other related 
species which will be discussed later. The sum of all the amino acids in lobster muscle 
is more or less ten times greater than the sum of all the amino acids in cat muscle. 
Mammalian organs vary in total free amino acid nitrogen concentrations from 10 to 
perhaps 50 mg/1oo g wet wt.*. In invertebrates the total free amino acid concentration 
is much higher. A comparison of the concentration of free amino acids in the muscle 
of the rooster with muscle of the lobster is given in Table II taken from a paper by 
FREDERICQ, BAcg AND FLORKIN‘. The distribution of nitrogenous compounds in 
aqueous extracts of lobster muscle and hepatopancreas is given in Table III (ref. 5). 
Again one can see that free amino acids make up a substantial fraction of the total 
non-protein nitrogen of the animal. High values for non-protein nitrogen are not 
characteristic of marine animals. In a comparison of values between marine inverte- 
brates and fishes, it was found that invertebrates (four species analyzed) contain 
from 210-370 mg of a-amino acid nitrogen whereas fishes contain only 9-72 mg of 
References p. 174/175 
