Phospholipase A₁activity of crude enzyme extracted from the ovaries of skipjack tuna

Abstract

The phospholipid class composition, fatty acid composition and phospholipase A1 (PLA1) activity from the ovaries of skipjack tuna were compared with those of six other species of marine fish. In the skipjack ovaries, the lysophosphatidylcholine (LPC) proportion for the phospholipid, the docosahexaenoic acid (DHA) percentage for the total fatty acids of the phospholipids and the PLA1 activity of the crude enzyme were the highest among those of the seven species. The optimum pH and temperature for the PLA1 activity of the crude enzyme from the skipjack ovaries were in the range of pH 6-7 and 20-30°C, respectively, and calcium ions were not required. As a substrate, phosphatidylcholine was more easily hydrolyzed than phosphatidylethanolamine by this enzyme, and the plasmalogen-type phospholipid was much lower than the acyl-type phospholipid. After a 6-h hydrolysis reaction of the purified phospholipid extracted from the mixed ovaries of skipjack and yellowfin tuna by this enzyme, the LPC ratio of the phospholipid increased from 20 to 72.6% and the percentage of DHA for the total fatty acids of the phospholipid also increased. Thus, skipjack ovaries might possibly be used as a source of PLA1.

Tuna Nutrition and Feeds: Current Status and Future Perspectives

“…The optimum pH and temperature for the phospholipase A 1 activity of the crude enzyme from ovaries were in the range of pH 6-7 and 20-30°C, respectively, and calcium ions were not required. As a substrate, phosphatidylcholine was more easily hydrolyzed than phosphatidylethanolamine by this enzyme as were diacyl phospholipids compared to plasmalogen phospholipids (Hiratsuka et al, 2008).…”

Energy allocation strategy of skipjack tuna Katsuwonus pelamis during their reproductive cycle

“…Previously, K. pelamis was defined as indeterminate batch spawners that present asynchronous oocyte development and a protracted spawning season (Stéquert & Ramcharrun, 1995, 1996Schaefer, 2001;Stéquert et al, 2001;Grande et al, 2012Grande et al, , 2014. Only a few of these studies, however, have focused on the lipid composition of reproductive tissues and, of these, most have concentrated on quantifying polyunsaturated fatty acid contents Watanabe et al, 1995;Hiratsuka et al, 2004Hiratsuka et al, , 2008Intarasirisawat et al, 2011) and on the development of bioenergetics models (Kitchell et al, 1978;Essington, 2003). One study only has dealt with lipid dynamics during the reproductive cycle of tropical tunas (T. albacares, Zudaire et al, 2014) and none have particularly focused on K. pelamis.…”

Lipid and Fatty Acids of Three Edible Myctophids, Diaphus watasei, Diaphus suborbitalis, and Benthosema pterotum: High Levels of Icosapentaenoic and Docosahexaenoic Acids

“…2.4 Preparation of methyl esters and gas-liquid chromatography GLC of esters Each crude lipid of three myctophids was converted to fatty acid methyl esters by direct trans-esterification with methanol containing 1 concentrated hydrochloric acid for 2.5 hr 22 . Individual components of TAG, PE, and PC fractions of K. pelamis were converted to fatty acid methyl esters by direct trans-esterification with methanol containing 1 concentrated hydrochloric acid under reflux for 1.5 hr, as previously reported, to produce the fatty acid methyl esters 15 .…”