口腔細菌叢の解糖作用を促進する唾液物質の分離

Abstract

The supernatant of human whole saliva separated by centrifugation contains low-molecular weight, thermostable, water-soluble and ninhydrin positive substances, which promote glycolysis of the salivary sediment and pure culture ofStr. mutans6715, Str. faecalisATCC 9790 andLact. caseiATCC 4646. These substances are reported by some investigators to be peptides or amino acids. We fractionated these substances by ion exchange chromatography, which is widely used for fractionation of peptides, using pyridine-acetic acid buffer, and examined their glycolytic-enhancing activity. Whole saliva was centrifuged at 26, 000×g for 20min. and separated into supernatant and sediment. The supernatant was dialyzed against distilled water through a cellophane membrane, and the dialysate was gel filtrated through a Sephadex G-25 column eluted with 0.2M acetic acid solution (pH 2.7). The ninhydrin positive fraction was chromatographed on the ion exchange resin Dowex 50W and eluted at the incremental pyridine concentration gradient of 0.2M pyridine-acetic acid (pH 3.1), 2M pyridineacetic acid (pH 5.0) and 4M pyridine-acetic acid (pH 5.6). Peptides and amino acids were assayed in the elute by the ninhydrin method after alkaline hydrolysis. A total of 15 fractions were obtained by Dowex 50W ion exchange chromatography. Glycolytic-enhancing activity was observed in fractions eluted at pH 3-4, which contained L-glutamine, L-glutamic acid, L-serine and L-proline. These individual amino acids did not promote glycolysis.