The Journal of biological chemistry . r magnitude wasobtained from fibrin. Our yield of lysine was not as good aswould be expected. This was not due to the absence of lysinein the cathode solution, but more probably to our unfamiliaritywith the method of isolating lysine as the picrate. The experi- G. L. Foster and C. L. A. Schmidt 551 mental results which are shown in Table III indicate also thatthe electrolytic method may prove useful in the preparation ofhistidine. When the reaction of the fibrin hydrolysate waskept at pH about 95 per cent of the hexone bases migrated tothe cathode comp
The Journal of biological chemistry . r magnitude wasobtained from fibrin. Our yield of lysine was not as good aswould be expected. This was not due to the absence of lysinein the cathode solution, but more probably to our unfamiliaritywith the method of isolating lysine as the picrate. The experi- G. L. Foster and C. L. A. Schmidt 551 mental results which are shown in Table III indicate also thatthe electrolytic method may prove useful in the preparation ofhistidine. When the reaction of the fibrin hydrolysate waskept at pH about 95 per cent of the hexone bases migrated tothe cathode compartment. On reelectrolysis of this solution atpH the major portion of the arginine and lysine was trans-ported to the cathode, while all of the histidine together withminimum quantities of arginine and lysine remained in thecenter compartment. The isolation of histidine from the histi-dine-rich solution may be carried out with the aid of the wellknown technique which has been described by Frankel (2) andby Hanke and Koessler (3).. Fig. 1. The experimental fact that when the reaction of the solution ofamino-acids is kept at pH the three basic amino-acids migrateto the cathode, while at pH histidine remains in the centercompartment and arginine and lysine migrate to the cathode isnot without a theoretical foundation. In Fig. 1 we have plottedthe percentage dissociation at varying pH of arginine, lysine,histidine, and alanine according to the well known method ofMichaelis (4), using the dissociation constants which have beenreported by Kanitz (5), Ley (6), Winkelblech (7), and Lunden(8). Since the amino-acids are amphoteric they can dissociateeither as acids or as bases depending upon the reaction of thesolution in which they are dissolved. At pH the isoelectricpoint of histidine, the latter is only slightly dissociated while 552 Separation of Hexone Bases arginine and lysine are dissociated as bases to the extent ofabout 40 per cent. At this reaction the latter am
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