Studies in Starch Amylase Viscosimetry

The viscosimetric method of estimating enzyme concentration was first developed by Northrop and Hussey (1). In studies of the effect of irradiation of trypsin and pepsin solutions by Hussey and Thompson (2) certain modifications of the original methods were employed in order to decrease the opportunity for personal influence in curve plotting, as in extrapolation for the initial viscosity of the digestion mixture. As their influence was of a secondary nature and interest was focused upon the irradiation effects, these modifications were not reported in detail until they were applied at a later date to starch amylase viscosimetry (3). The immediate objective was to facilitate the work of Johnson and Wies (4, 5) with the amylase of dog serum and to establish some basis for estimating the reliability of the method to be used. The method was good enough for the immediate purpose, but it was pointed out that serious difficulty was to be expected in reproducing a standard substrate solution unless the same lot of soluble starch were employed. As noted (3) this was adopted as a temporary expedient, but the method was modified almost immediately. Davison (6) had suggested a method for the viscosimetric estimation of amylase, but gave no data from which the reliability of the method might be gaged. Chesley (7) tested a suggestion of Davison that with different lots of starch the concentration in the substrate solution be adjusted to give the same viscosity, and in this way obtained (with somewhat extreme cases, however) a