Distribution of free L-histidine and its related compounds in marine fishes.

By high-performance liquid chromatography the distribution of L-histidine, carnosine, anserine, and balenine was examined in the white and red muscles of nine species of marine fishes. The L-histidine contents of white muscle were 15.8-92.8μmol/g in dark-fleshed fishes, 0.0734-0.931μmolg in white-fleshed fishes, and 4.06-20.3μmol/g in intermediate fishes. The L-histidien contents fo red muscle were lower than that of white muscle. Balenine as well as 1-and 3-methy ?? -L-histidine was detected only in a trace amount in a few species. In contrast, carnosine and anserine were found in the white and red muscles of almost all species, in which skipjack white muscle showed the highest contents of 2.46-5.57μmol/g (carnosine) and 7.69-21.2μmol/g (anserine). In skipjack tuan, L-histidine, carnosine, and anserine were distributed at somewhat higher levels in dorsal white muscle than in ventral muscle. The level of each compound differed significantly among the anterior, middle, and posterior portions of skipjack red muscle. In skipjack tuna, L-histidine was also detected in other tissues, such as intestine, stomach, pyloric caecum, with the highest level of 20.9μmol/g in pyloric caecum. Carnosine and anserine were also present in these tissues, but in smaller amounts.