Studies on the amylolytic activity of human saliva with a new method

Abstract

Saliva is the one glandular secretion which can be readily obtained in the human subject under relatively constant conditions, and its amylolytic activity has therefore been a time-honored topic of investigation. Nevertheless the methods used for estimating this activity have been rather crude or tedious. A method is described below which is simple, delicate, and, we believe, very accurate. With it a large series of comparable figures may readily be obtained. The method is similar to that which has been employed here in estimating the diastatic activity of the blood. 1

The technique is as follows: A specimen of mixed saliva, obtained by the stimulation of paraffin chewing, is filtered and a small portion accurately diluted 1 to 100 with distilled water, and also another portion with 0.3 per cent. sodium chloride as an activating solution. After thorough mixing 1 c.c. of the diluted saliva is pipetted into a test-tube and the tube placed in a water bath at 40°. After 5 minutes 1 c.c. of 1 per cent. soluble starch solution is added and the mixture allowed to incubate for 30 minutes. At the end of this time 3 c.c. of saturated picric solution and 1 c.c. of 20 per cent. sodium carbonate are added and the tube placed in boiling water for 15 to 20 minutes. It is then allowed to cool and diluted with distilled water in an accurately graduated cylinder until the intensity of the color approximates that of the standard (glucose in picric acid treated with sodium carbonate and heated), after which it is compared with the standard in the calorimeter. After correcting for the reducing power of the soluble starch, the activity is recorded in terms of the percentage of starch converted to reducing sugar.