Trypsin solution behavior

Partial hydrolysis of elastin by reagents other than organic acids also gives rise to a mixture of soluble proteins similar to a- and /3-elastin. Thus Wood (quoted by Hall et al, 1952) first demonstrated that partial hydrolysis with dilute sodium hydroxide yields a protein which forms a reversible coacervate on raising the temperature of its solutions. Later Wood (1958) showed that on prolonged heating in aqueous solution a-elastin is converted into an insoluble gellike form. Reconstituted fibers of heat-treated a-elastin resembled fibrous elastin in their elastic behavior and X-ray-dif-fraction pattern but imlike purified elastin they were dissolved by 1 % acetic acid at 100°C and by crystalline trypsin. 

Trypsin in aqueous solution has been studied by a simulation with the conventional periodic boundary molecular dynamics method and an NVT ensemble.312 340 A total of 4785 water molecules were included to obtain a solvation shell four to five water molecules thick in the periodic box the analysis period was 20 ps after an equilibration period of 20 ps at 285 K. The diffusion coefficient for the water, averaged over all molecules, was 3.8 X 10-5 cm2/s. This value is essentially the same as that for pure water simulated with the same SPC model,341 3.6 X 10-5 cm2/s at 300 K. However, the solvent mobility was found to be strongly dependent on the distance from the protein. This is illustrated in Fig. 47, where the mean diffusion coefficient is plotted versus the distance of water molecules from the closest protein atom in the starting configuration the diffusion coefficient at the protein surface is less than half that of the bulk result. The earlier simulations of BPTI in a van der Waals solvent showed similar, though less dramatic behavior 193 i.e., the solvent molecules in the first and second solvation layers had diffusion coefficients equal to 74% and 90% of the bulk value. A corresponding reduction in solvent mobility is observed for water surrounding small biopolymers.163 Thus it... 

Time effects have also been observed for bovine plasma albumin, horse serum albumin and rabbit y-globulin (Beaven and Holiday, 1950). The behavior of bovine plasma albumin was most striking the intensity of the absorption in 0.1 N alkali increased steadily over a period of ca. 3 hours at room temperature the light-scattering properties of the solution, as shown by its apparent absorption on the long-wave side of the absorption band proper, also increased. Of the few proteins which were examined, only lysozyme showed no time effect. With trypsin the change in absorption was small and complete in a few minutes at pH 13, but the solution then became visibly turbid. 

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