The distribution of urea, trimethylamine oxide (TMAO), anserine, and balenine was studied on the muscle of six different species of marine elasmobranchs. In all species tested, the sum of urea-N and TMAO-N corresponded to 60-76% of the extractive nitrogen. A relatively high amount of anserine was observed in some species, and when anserine-N was taken into consideration, the total reached 74-80%.
The amounts of other nitrogenous constituents, such as free and combined amino acids, trimethylamine, creatine, creatinine, and nucleotides, were compared on the muscle of Mustelus kanekonis and Lamna cornubica which had been found to contain small and large amounts of anserine, respectively, Nearly 97% of the extractive nitrogen was accounted for in each sample, and it was observed that the distribution pattern of the constituents was not varied, except for that of nucleotides.