DIFFERENTIAL REACTIVITIES OF HYPOCHLOROUS AND HYPOBROMOUS ACIDS WITH PURIFIED ESCHERICHIA-COLI PHOSPHOLIPID - FORMATION OF HALOAMINES AND HALOHYDRINS

Hypochlorous (HOCl) and hypobromous (HOBr) acids are strong oxidants d erived from myeloperoxidase and eosinophil peroxidase, the major antim icrobial enzymes of neutrophils and eosinophils, respectively. These o xidants are highly reactive with a wide range of biomolecules. At phys iological pH, both HOCl and HOBr react readily with amines to form hal oamines and with the unsaturated bonds of fatty acids to form halohydr ins. We have investigated which of these reactions occur with phosphat idylethanolamine (PE), the predominant phospholipid of Escherichia col i. The formation of haloamines was determined by TLC and colorimetrica lly and the formation of halohydrins was determined by TLC and GC-MS. With HOCl, chloramines were much the preferred product and chlorohydri ns were formed in substantial amounts only when HOCl was in excess of the amount required to convert the amine to the dichloramine. With HOB r at all concentrations. bromamines and bromohydrins were formed concu rrently, indicating a greater relative reactivity with unsaturated fat ty acids than with HOCl, The bromamine derivatives of PE, and other pr imary amines, were found to be more reactive than the equivalent chlor amines, and were able to brominate the unsaturated bonds of fatty acid s. Bromohydrins (formed directly or through the action of bromamines) may, therefore, be suitable biomarkers for the production of HOBr in v ivo. (C) 1998 Elsevier Science B.V.