Determination of Molecular Species of Phospholipids from Thermophilic Bacterium PS3 by Mass Chromatography1

Abstract

The molecular species of phosphatidylethanolamine, phosphatidyiglycerol and cardiolipin of thermophilic bacterium PS3 were determined by a new and simple mass chromatographic technique. The fatty acyl groups of these compounds, unlike those of usual phospholipids, were all saturated and were mixtures of even and odd numbered carbcn chains; their [M-C_n-CH_2n+1-COOCH]⁺ and [M-C_n+1-H_2n+1-COOCH]⁺ peaks overlapped. Thus, the acetyldiglycerides derived from these phospholipids were subjected to a combination of mass chromatography using chemical ionization with NH₃ and treatment of the phospholipids with phospholipase A₂ [EC 3.1.1.4]. These three phospholipids had similar patterns of diglycerides. Expressed as R¹ : R²%, they were found to be 14 : 14, 0–1%, 15 :14, 0–4%, 15 : 15, 22–;32%, 16 : 15, 16–20%, 17 :15, 28–32%, 17 : 16, 6–9%, 18 :15, 7–13%, 17 : 17, 3–6%, and 18 : 16, 0–1%. These results should be of significance in connection with the high stability of the biomembranes of this bacterium.