Fig. 2.

The major signal from band 4 of crude lipid represents saturated phosphatidylethanolamine (PE) (24: 0/–10: 0). a The dominant mass signal in positive-ionization mode at m/z 720.560 was consistent with the protonated molecular ion for PE with fatty acid chains totaling 34 carbons and zero double-bonds. b High-collision energy under positive ionization showed that a major signal at m/z 579.538, consistent with the neutral loss of 141 Da from the 720.560-m/z species which is diagnostic of PE lipids. A concomitant neutral loss from m/z 692 (producing 551) also indicates PE (32: 0). A fragment ion at m/z 184 (not shown) also supports the phosphatidylcholine (PC) (34: 0) annotation. c Negative ionization analysis with high-collision energy conditions revealed several m/z values in the fatty acid (FA) molecular ion mass range. Of these, both saturated C10 (171.141) and C24 (367.375) were observed, which collectively confirms PE (34: 0) with a composition of 24: 0/–10: 0. d Suggested structure of PE identified in band 4 of crude SchuS4 lipid.