Role of free L-histidine-related compounds in marine animal muscle

点击翻译按钮获取中文摘要

Effect of temperature was examined on the buffering capacity (BC) of histidine (His) and related compounds and of the marine animal muscle. Distribution of trace amounts of His-related compounds in fish and invertebrate muscle was also examined.1. BC of inorganic phosphate, carnosine (Car) and anserine (Ans) in the pH range of 6.5-7.5 were very high and stable within the temperature range, from 5 to 40ﾟC. His and balenine (Bal), however, showed rather low BC and large decrease with increasing temperature. His-related compounds, however, were not considered to be the most suitable buffering constituents because the other dipeptides such as Ala・His and Ser・Ala also showed high BC and no temperature dependence.2. White muscle of skipjack tuna containing high His and Ans showed the highest muscle BC, followed by little-piked whale muscle containing high Bal. BC of these muscle declined with increasing temperature at above 20ﾟC. Muscle BC of several other fish containing little His- related dipeptides was low and showed almost no temperature dependence.3. Contribution of extractive components to muscle BC was high, ranging from 48 to 96 % according to the fish species, but that of muscle proteins were low, ranging from 20 to 34 %, His-related compounds and phosphate showed above 70 % contribution to the BC of muscle extract. Although the BC of phosphate did not differ largely among fish species, His-related compounds showed large difference in BC and contributed more than 60 % to the extract BC in case of skipjack and whale.4. Trace amounts of Car, Ans, and Bal were found in all the muscle examined including 13 species of fresh water fish and 8 species of shrimp and clam. This fact suggests that the small amounts of these dipeptides should play another important physiological role than buffering constituents in every animal muscles.