Researches on the nature of enzyme-action. I, On the causes of the rise in electrical conductivity under the action of trypsin / by W.M. Bayliss.

William Bayliss

Date:: [1907?]

Credit: Researches on the nature of enzyme-action. I, On the causes of the rise in electrical conductivity under the action of trypsin / by W.M. Bayliss. Source: Wellcome Collection.

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$Owing to the considerable time taken in these manipulations I have only been able to prepare glycocol, alanine, leucine and glutamic acid by the ester method. Glycocol. The ethyl-ester was prepared from the hydrochloride as supplied by Kahlbaum. This was distilled under diminished pressure, a considerable part remaining inthe flask. The distillate was hydrolyzed by boiling for several hours with conductivity water in a Jena glass flask with a reflux condenser also of Jena glass. The free amino-acid m 10 solution of this was found to have a conductivity of 10°4 gemmhos; the water used had a conductivity of 1:9 gemmhos, so that the value for the glycine itself was 8°5 gemmhos. The glycocol used had a melting-point of about 240°, determined by the method of Kutscher and Otori!, but it began to char before melting. was recrystallized from dilute alcohol, washed with alcohol and ether and dried. A That the setting-free of glycocol produces an increase in con- ductivity is shown by the experiments of Euler?, who found such to take place in the action of erepsin on glycyl-glycine. I have found that a similar rise takes place in the action of trypsin on glycyl-tyrosin, in fact a 5°/, solution, which was not free from ammonium chloride, showed a rise of about 900 gemmbhos in four days. The “biuret-base ” of Curtius, which is tri-glycyl-glycine-ethyl-ester*, also shows an increase in conductivity on hydrolysis. Further experiments on poly- peptides are in progress. For the present purpose it is sufficient to note that the setting-free of glycine produces a rise in conductivity. Leucine was obtained by fractional distillation under reduced pressure of the ethyl-esters of the first crop of crystals coming out on concentration of a tryptic digestion of caseinogen, the tyrosin having first been filtered off. A small amount of distillate was collected below 40° at a pressure of 35 mm. Hg, this consisted chiefly of alcohol and was rejected. Nothing more came over until a bath-temperature of 75°—80° was reached, at which temperature and at a pressure of 2 mm. Hg a considerable quantity was collected. Again, no further distillate came over until 120° in oil-bath was reached, when a second large amount was collected. The fraction coming over at 80° was no doubt nearly pure leucine-ester. It was hydrolyzed by boiling with water as described for glycine, most of the leucine crystallizing out on cooling. The melting-point was found to be, in sealed tube, 280°. The value found by Fischer was some 7° or 8° higher. Cohn found 275°—276°. The differences are probably to be explained by the effect of varying rates of heating. The solubility of the preparation in water at 38° was 3:17°/,. Its rotatory power was, in 21°9°/, HCl, [a], =+18-16°. 1 Zeitsch. f. physiol. Chem. xurt. p. 193. 1904. > Zeitsch. f. physiol. Chem. ut. p. 213. 1907. * Curtius, Ber. d. D. Chem. Ges. xxxvut. p. 1284. 1904.$