PROTEINACEOUS PRECURSORS OF HUMAN AXILLARY ODOR - ISOLATION OF 2 NOVEL ODOR-BINDING PROTEINS

The characteristic odor which arises in the human axillary region cons ists of volatile C-6-C-11 acids with the most abundant being (E)-3-met hyl-2-hexenoic acid (E-3M2H). This acid, as well as several other comp onents of the characteristic axillary odor, can be liberated from the odorless, aqueous soluble components of apocrine secretion by either s aponification or bacteriolysis. It is therefore likely that a major ch aracteristic odor is being carried to the skin surface bound to a wate r soluble precursor where it is liberated by axillary bacteria. The in dividual proteins found in apocrine secretions were separated, isolate d and hydrolyzed with the resultant hydrolyzates analyzed by gas chrom atography/mass spectrometry. These studies demonstrated that 3M2H was liberated from 2 proteins with apparent molecular mass of 26 and 45 ki lodaltons: Apocrine Secretion Odor-Binding Protein 1 and 2, respective ly (ASOB1 and ASOB2). Antisera to these proteins were prepared and use d to examine a variety of other body fluids. Several fluids contained an immunoreactive protein with the same electropheretic migration patt ern as the 45 KDa protein. Three of these body fluids (tears, nasal se cretions and saliva) were separated into aqueous and organic soluble f ractions and hydrolyzed to demonstrate that 3M2H could be liberated fr om the aqueous soluble materials. These results suggest interesting pa rallels between non-human mammalian odors used as chemical signals and human axillary odor. Previous studies have suggested the axillae as a source of human primer-type pheromones; consequently, if the odors wh ich characterize the underarm are responsible for the pheromonal activ ity, then the chemistry involved may be similar to that in other mamma lian chemical communication systems where proteins act as carriers of one or more chemical signals.