208 MITCHELL HYDROLYSIS OF THE ~-OLUCOSIDES ETC. XXXIII. -Hydrolysis of the d-Glucosides of d- and l-Borneo1 with Emulsin. By STOTHERD MITCHELL. DAKIN ( J . PhysioE. 1904 30 253) found that when an optically inactive mixture of t'he two methyl mandelates was acted upon by the enzyme lipase the dextro-component was hydrolysed more rapidly than the kevo. Substitution of other alkyl groups for methyl produced differences in the relative rates of hydrolysis, and in order to investigate the effect of optically active groups he prepared I-menthyl mandelate and d-bornyl mandelate. Lipase, however was without action on these compounds. Later (ibid., 1905 32 199) he succeeded in hydrolysing esters in which an asymmetric carbon atom was present in the alkyl group but not in the acid part of the molecule.The hydrolysing action of emulsin on the d-glucosides prepared from the two forms of borneol has now been examined. The d-borneol was obtained from commercial " borneol," which is a mixture of d-borneol and I-isoborneol resulting from the reduc-tion of camphor (Pickard and Littlebury J. 1907 91 1977). The purified d-borneol and the I-borneol used had [m]2;igreen = + 42-14' and - 42-20' respectively calculated from 15.4% solutions in dcohol. The p-glucosides of d- and I-borneol were prepared by treating p-tetra-acetylbromoglucose in ether with an excess of borneol i SONE CO-ORDINATED COMPOUNDS OF THE ALKALI METALS. 209 presence of silver carbonate the acetyl groups being subsequently removed by means of barium hydroxide (Fischer and Raske Ber., 1909 42 1473 ; Fischer Ber.1916 49 584 ; Hamalainen Biochern. Z. 1913 50 217). Emulsin (2.5 g.) was mixed with 180 C.C. of water and kept in a thermostat a t 37" for a day. The solution was filtered before use and gave E:; green - 0.64" (I = 1 dcm.). A small quantity (0.3 g.) of each glucoside (which contains 1H,O) was placed in a 50 C.C. flask in a thermostat a t 37". The hydrolysis of the d-bornyl-d-glucoside was started by filling the flask to the mark wit,h the emulsin solution and an hour later the hydrolysis of the I-bornyl-d-glucoside was commenced. Two C.C. were removed a t intervals and the amount of glucose present was determined by IiIacLeaa's method for estimating the sugar in blood (Biochern. J., 1919,13 135). The reaction constants are calculated from thc usual formula for unimolecular reactions k = {2.3O/(t - t,)l log (cz/c,).Time in mins. 2 70 330 515 613 860 ( = t Y ) d- BoriLyl-d-gliLcoside. Glucose. Glucositle. Time IIg. in BIg. in in 2 C.C. 2 C.C. k x lo5. mins. 0.70 10.13 10 1 so 0.77 10.01 9 303 0.82 9.92 11 36 1 0.89 9-80 1 0 43.5 1-03 9.55 673 Average 10 ( = t g ) I- Bomyl-d -p! zlcos ide. Glucose. Glucoside. 31s. in Mg. in 2 C.C. 2 C.C. k x 10". 0.87 9.83 34 1-12 9.39 33 1.2% 9.22 33 1-33 9.03 35 1.74 5-3 1 ,4veragc 3-1 Hence emulsin hydrolyses I- bornyl-d-glucoside 3-4 time as This is a striking example of the rapidly as d-bornyl-d-glucoside. selective nature of enzyme action. PHYSICAL CHEMISTRY DEPARTMENT, UNIVERSITY OF GLASC:OW.[Received Xovenlber 24th 1924. 208 MITCHELL HYDROLYSIS OF THE ~-OLUCOSIDES ETC. XXXIII. -Hydrolysis of the d-Glucosides of d- and l-Borneo1 with Emulsin. By STOTHERD MITCHELL. DAKIN ( J . PhysioE. 1904 30 253) found that when an optically inactive mixture of t'he two methyl mandelates was acted upon by the enzyme lipase the dextro-component was hydrolysed more rapidly than the kevo. Substitution of other alkyl groups for methyl produced differences in the relative rates of hydrolysis, and in order to investigate the effect of optically active groups he prepared I-menthyl mandelate and d-bornyl mandelate. Lipase, however was without action on these compounds. Later (ibid., 1905 32 199) he succeeded in hydrolysing esters in which an asymmetric carbon atom was present in the alkyl group but not in the acid part of the molecule.The hydrolysing action of emulsin on the d-glucosides prepared from the two forms of borneol has now been examined. The d-borneol was obtained from commercial " borneol," which is a mixture of d-borneol and I-isoborneol resulting from the reduc-tion of camphor (Pickard and Littlebury J. 1907 91 1977). The purified d-borneol and the I-borneol used had [m]2;igreen = + 42-14' and - 42-20' respectively calculated from 15.4% solutions in dcohol. The p-glucosides of d- and I-borneol were prepared by treating p-tetra-acetylbromoglucose in ether with an excess of borneol i SONE CO-ORDINATED COMPOUNDS OF THE ALKALI METALS. 209 presence of silver carbonate the acetyl groups being subsequently removed by means of barium hydroxide (Fischer and Raske Ber., 1909 42 1473 ; Fischer Ber.1916 49 584 ; Hamalainen Biochern. Z. 1913 50 217). Emulsin (2.5 g.) was mixed with 180 C.C. of water and kept in a thermostat a t 37" for a day. The solution was filtered before use and gave E:; green - 0.64" (I = 1 dcm.). A small quantity (0.3 g.) of each glucoside (which contains 1H,O) was placed in a 50 C.C. flask in a thermostat a t 37". The hydrolysis of the d-bornyl-d-glucoside was started by filling the flask to the mark wit,h the emulsin solution and an hour later the hydrolysis of the I-bornyl-d-glucoside was commenced. Two C.C. were removed a t intervals and the amount of glucose present was determined by IiIacLeaa's method for estimating the sugar in blood (Biochern. J., 1919,13 135). The reaction constants are calculated from thc usual formula for unimolecular reactions k = {2.3O/(t - t,)l log (cz/c,). Time in mins. 2 70 330 515 613 860 ( = t Y ) d- BoriLyl-d-gliLcoside. Glucose. Glucositle. Time IIg. in BIg. in in 2 C.C. 2 C.C. k x lo5. mins. 0.70 10.13 10 1 so 0.77 10.01 9 303 0.82 9.92 11 36 1 0.89 9-80 1 0 43.5 1-03 9.55 673 Average 10 ( = t g ) I- Bomyl-d -p! zlcos ide. Glucose. Glucoside. 31s. in Mg. in 2 C.C. 2 C.C. k x 10". 0.87 9.83 34 1-12 9.39 33 1.2% 9.22 33 1-33 9.03 35 1.74 5-3 1 ,4veragc 3-1 Hence emulsin hydrolyses I- bornyl-d-glucoside 3-4 time as This is a striking example of the rapidly as d-bornyl-d-glucoside. selective nature of enzyme action. PHYSICAL CHEMISTRY DEPARTMENT, UNIVERSITY OF GLASC:OW. [Received Xovenlber 24th 1924.