Identification by mass spectrometry of CMP-NANA in diffusible material released from high M(r) blood cell fractions that confers serum resistance on gonococci.

In previous work, a low M(r) component from human blood which converts serum-sensitive gonococci to resistance was shown to be indistinguishable from cytidine 5'-monophospho-N-acetyl neuraminic acid (CMP-NANA) by seven criteria. However, the presence of CMP-NANA was not proved by physicochemical methods. Purified, high M(r) fractions from human blood cells, which confer serum resistance on gonococci and enhance the transfer of sialyl groups from CMP-NANA to lipopolysaccharide (LPS) by a sialyltransferase in gonococcal extracts, were rechromatographed on DEAE Sepharose CL-6B. Both activities co-eluted from the column but on dialysis were found in the diffusate. After desalting the diffusate with Sephadex G10, the presence of CMP-NANA was proved by mass spectrometry. This confirmed previous work and is the first unequivocal demonstration of CMP-NANA in constituents of human blood cells.