Synthesis and Hydrolysis of Wax Ester in Mullet

MANKURA Mitsumasa, KAYAMA Mitsu

doi:10.5650/jos1956.38.394

The functions of enzymes in WE synthesis by plasma and roe and liver homogenates from the mullet, M. cephalus, were studied so as to clarify the metabolism of roe lipid in fish rich in wax esters (WE). The fish examined was 4, 130g in wet weight with a gonad index of 10.7. The roe was 17.6% lipid on a wet weight basis, and the amount of WE in the lipid was about 70%. Carbon numbers ranged from 30 to 34 and the major fatty acids were 16: 1 and 18: 1, and the major fatty alcohols, 16: 0 and 16: 1.<BR>WE syntheses from [1-¹⁴C] oleic acid and [1-¹⁴C] oleyl alcohol as well as the hydrolyses of oleyl [1-¹⁴C] oleate occurred to the greatest extent in the roe homogenate. The highest specific and greatest total reducing activity of [1-¹⁴C] oleic acid was also observed in this homogenate. WE synthesizing activity in roe was mainly associated with the 105, 000×g pellet and supernatant, in which WE formation from [1-¹⁴C] oleic acid was activated by the addition of ATP, CoA and NADPH. Plasma also possessed activity for WE synthesis from [1-¹⁴C] oleic acid, and its activity increased with cold oleyl alcohol in the reaction mixture.<BR>The enzymes directly related to WE synthesis from fatty acids in the mullet roe may be possibly acyl CoA: alcohol acyltransferase and fatty acid reductase, while those in plasma appear to be lecithin: alcohol acyltransferase instead of lecithin: cholesterol acyltransferase. The high content of WE in roe is possibly due to nutritional requirements and the buoyancy of eggs after hatching. The WE in roe may be one reason for its unique biochemical adaptation.

Synthesis and Hydrolysis of Wax Ester in Mullet

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