Abstract
As most of the methods for determination of fish muscle proteins are more or less tedious, a more convenient m ?? th ?? d has been desired. The SNOW's method (1950)4)which was followed at first by the authors revealed that the linearity between light absorption and protein concentration did not hold for protein concentration beyond 0.3mg. N/ml., and that the formation of turbidity often disturbed the measurement (Fig. 1 Curve-A). Thence a reagent proposed by SOLS (1947)5) was examined. By use of this reagent, the constancy of the absorption increment was kept up to 0.4mg. N/ml. (Fig. 1, Curve B). As for turbidity it was observed that the turbidty increased as a function of time after combining the sample solution and the reagent, and that the turbidity could be removed by centrifuging or filtration (Fig 3). Thus the method was defined as below.
The reagent, which is composed of 0.4% CuSO45H2O, 8% NaOH and 0.2% glycerol, is added to an equal volume of the sample solution, and mixed. After standing for from 3 hours to overnight the mixture is centrifuged for 10-15 minutes by 3, 000 r.p.m. or filtered with no. 3 glass-filter. The optical density of the supernatant or the filtrate is evaluated at the wavelength cf 545mμ, and protein concentration is calculated by the aid of a coefficient determined previously (Table 1). The standard error of the analysis was as low as ±1.98%.
When it was ?? ceded to obtain a rough measure of a protein concentration as quickly as possible, and also in the expen ?? of the accuracy, the authors took advantage of the SNOW's method in which the measurement is performed between 25-40 minutes after combining the sample and the reagent and without removing turbidity.
