Paper Electrophoresis of Saliva *

Organic constituents of human saliva vary around 0.5 g. per 100 ml. depending on the nature of the stimulus and the hour of collection. Most of the organic matter is protein, with mucin being the preponderant component. However, it is one of the smaller protein elements that has been the most widely studied, mainly because of its enzymatic action, that is, salivary amylase. Phase boundary electrophoresis studies have been reported by Blix2 on animal submaxillary mucin and by Bernfeld, Staub, and Fischer' and Muusu on human salivary amylase. In the present note, electrophoresis was carried out on whole human saliva. The method reported here is that of zone paper electrophoresis"' 18M17 which utilizes filter paper as a matrix to support the buffer solution. This method offers the following advantages over the phase boundary-free solution technique of Tiselius.'5 1. By means of paper electrophoresis many determinations may be made with a volume needed for but a single sample in the phase boundary apparatus. 2. Less than 0.1 ml. samples will usually suffice for paper electro-phoresis; with amounts this small, it is not possible to use phase boundary electrophoresis. 3. Optical transparency of samples is not necessary with paper electro-phoresis. 4. Preparative dialysis against the buffer, which may induce degradative changes in complex materials such as saliva, is not a requirement because inorganic ions do not interfere with electrophoresis when using filter paper. 5. Separation of components by paper electrophoresis is more permanent than that produced by the phase boundary apparatus because the filter paper provides a matrix in which the protein elements are retained in their relative positions after completion of electrophoresis. 6. Enzyme migration may be traced after paper electrophoresis by testing sections of the filter paper with a suitable substrate for the specific