the Optical Rotation of the Proteins of Blood Sera. 



181 



of purity. However, the literature of the subject revealed the widest 

 disparity of figures for the same protein, and as reliable data did not appear 

 to be available, recourse was had to determining the concentrations of the 

 solution by chemical means and to taking advantage of the opportunity which 

 the principal work afforded of determining the specific rotations of the several 

 proteins. In view of the separations having been carried out with such 

 thoroughness, the figures should be fairly accurate and reliable. 



There is probably a normally definite specific rotation for each of the 

 globulins, although experimental results do not favour this view with regard 

 to the albumins. On the other hand, one must take into consideration such 

 cases as that of the pseudo-globulin from specimen No. 201. The specific 

 rotation was determined twice on two entirely independent solutions of 

 different concentration, the concentrations having to be ascertained separately 

 by chemical means. The two results are — 43'26° and — 43'82°, whereas the 

 adopted figure for other pseudo-globulins is — 46°. This seems to show that 

 if there is a normal value, there are specimens having abnormal values. A 

 study of the figures as a whole leads to the conjecture that a given specimen 

 may be pure in the chemical sense, but consist of a mixture of optical 

 isomers of the protein. A closer examination of the data reveals many 

 irregularities not apparent at first sight. For example, the two most recent 

 and best specimens of pseudo-globulin from the horse had the specific 

 rotations — 52 - 06° and — 52-17°, while an earlier specimen gave — 49 - 50°. 

 Corresponding specimens of human origin gave —43-5°, — 46-97°, — 47 - 66°, 

 and — 45 - 35°, the first three having been separated from ascitic fluid and the 

 last from normal serum. There is thus exhibited a well-marked differentia- 

 tion between the rotation of the human, which may be taken as —46°, and 

 that of the horse, which may be taken as —52°. 



Similarly with eu-globulin : the figures for the two best and most recent 

 specimens of horse are — 43 - 03° and — 43'04°, and for an earlier one — 40 - 98°. 

 The human gave -50-24°, -49-12°, -47-13°, and -47 "8 9°, the first three 

 referring to the protein separated from ascitic fluid and the last from normal 

 serum. 



From these one may adopt —43° for eu-globulin from horse and —48° for 

 the human. 



"With albumin the results fluctuated considerably. For horse — 57'40° is 

 the only figure available. For human, -65-36°, -64-43°, -55-05°, -59-14°, 

 — 50-58°, —54-83°, the first four referring to albumin separated from ascitic 

 fluid, and the last two to that from normal serum. 



The rotations were observed with solutions containing a little ammonium 

 sulphate. By experiment it was ascertained that the change of rotation 



