Phospholipid fatty acyl distribution of three fungi indicates positional specificity for n‐6vs. n‐3 fatty acids

Abstract

AbstractPhospholipids of the fungiConidobolus nanodes, Entomophthora exitalis andSaprolegnia parasitica were extracted and analyzed. The phospholipid content was the same (2.4%) for the three species and was independent of the total lipid content. Phospholipase A2 degradation of individual phospholipid classes showed an asymmetrical distribution of polyunsaturated fatty acids (PUFA) between the two fatty acyl positions of glycerol. There was a predominance of n‐6 PUFA at position 2 and a predominance of n‐3 PUFA at position 1. WithC. nanodes andE. exitalis, 20∶5n−3 is derived from 18∶3n−3 and is located predominantly at position 1. InS. parasitica 20∶5n−3 is synthesized from 18∶3n−6via 20∶4n−6 and is located predominantly at position 2. It is suggested that the asymmetrical distribution of PUFA between positions 1 and 2 of glycerol Points towards different sites of synthesis of the two classes of PUFA, and that cross‐over between PUFA of the different types is prevented by thesn‐1 orsn‐2 positional specificity of the desaturases.