Surface tension and ferment action

Abstract

The following investigations were carried out with the object of determining whether the action of a ferment on a substance is affected by surface tension. Since in the living organism the action of ferments proceeds in a system in which surface development has reached a maximum, the problem is one of considerable theoretical importance . So far as we are aware, it has not been studied. The experimental difficulty is, of course, to allow the factor of surface tension to operate on the action of ferments in such a way that a sufficient amount of the digest can be obtained at the end of the experiment in which the progress of the ferment action be determined. Various devices were used to attain this object. In some preliminary experiments the reaction was allowed to proceed in a capillary tube, in others in test-tubes filled with glass wool, with thin short capillary glass tubes or with glass beads. The reaction as it proceeded in these tubes was then compared with that of a control in an ordinary test-tube. A distinct effect was observed in these preliminary experiments with lipase, distase, and yeast invertase, all of which showed a retardation. The effect was then studied in some detail in the case of invertase. The experiments with invertase were carried out as follows:-Solutions of sucrose and invertase were mixed in definite proportions. Part of the mixture was placed in a test-tube and served as a control. The rest was put into test-tubes filled with glass beads, 3 to 4 mm. in diameter. Care was taken that the level of the fluid was always well below the top level of the glass beads. The tubes were then closed with a rubber stopper and incubated at a given temperature. After a given number of hours, readings were taken with a polarimeter. In every series of experiments the control tubes were read first, so that the slightly prolonged period of incubation in the tubes filled with beads would tend to diminish any retardation that might occur. Special control experiments showed that the presence of glass beads did not affect the readings obtained with pure sucrose solutions. Similarly the readings obtained with solution of invertase alone remained constant. That the effect of the mutarotation of the glucose formed by the action of invertase could be neglected will be pointed out below. The beads were washed after each experiment for several hours, first in hot running tap water, then with distilled water, and dried in an oven at about 180°C.