Fig. 3.

Activity of RSP2144 in vitro. (A) Properties of a recombinant RSP2144 protein when assayed for incorporation of ³H-methyl–labeled SAM into tricholoroacetic acid insoluble material using micelles containing native R. sphaeroides phospholipids as a substrate. (B) FAME products obtained using R. sphaeroides lipids in the absence (negative) or presence of His₆-RSP2144 protein (UfaM) and SAM (2 h and overnight time points). The chromatographic response of lipids before and after 2 h or overnight incubation with UfaM in vitro shows an increase in 19M-UFA concentration when incubated with UfaM (shaded in gray). The spectra (Right) show the ACN PCI [M+MIE]⁺ MS/MS (25 eV) spectra collected at the apex of the 19M-UFA peak in all three samples, with key fragment ions labeled. No 19M-UFA was detected in the reactions lacking UfaM (negative).