The relationship between fatty acid structure and the positional distribution of esterified fatty acids in phosphatidyl glycerol from Mycoplasma laidlawii B

Abstract

1. 1. The distribution of a number of fatty acids between the 1- and 2-positions of phosphatidyl glycerol from Mycoplasma laidlawii B has been investigated. The fatty acid composition of the phosphatidyl glycerol was systematically altered so that the positional distribution values determined here are accurate reflections of the relative positional affinities of the individual fatty acids examined. 2. 2. The positional distribution of any given fatty acid constituent was independent of the amount of that acid in the phosphatidyl glycerol, provided that the fatty acid in question was not present in sufficient quantity to saturate the preferred position. 3. 3. Within any single class of fatty acids, the positional specificity was markedly dependent on the chain length of the fatty acid. The smaller the total number of carbon atoms, the lesser was the affinity for the 1-position. 4. 4. Positional distribution was also dependent on the structural characteristics of the fatty acids. The following is the order of the fatty acid classes arranged according to a decreasing affinity for the 1-position: straight-chain saturated > branched-chain saturated > trans-monounsaturated > cis-monounsaturated > cyclopropane > cis-diunsaturated.