PHYSICAL AND CHEMICAL PROPERTIES OF SNAKE VENOM 83 



globulin-magnesium precipitate allowed a small trace of albuminous body 

 to diffuse outside the dialyzer, and the latter gave the precipitate with acetic 

 acid and ferrocyanide of potassium, indicating that this was an acid albumin. 

 Judging from this he thought the dialyzable protein of venom could not be 

 a peptone, but an acid albumin. 



Serum albumin: A very small quantity precipitable with NaaSO* from 

 the magnesium nitrate of venom was obtained, but precipitation required 

 many hours shaking. It coagulated in redissolved condition at between 

 70 and 80 C. 



Syntonin: Some fraction was obtained from the nitrate of an aqueous 

 solution of venom previously heated to 98 C. for 10 to 15 minutes by means 

 of saturated MgSO 4 , and still more completely by boiling the nitrate with 

 solid MgSO 4 in saturation. Usually this frees the venom solution of any 

 protein matter, but there may be some exceptions, which Wolfenden, in that 

 case, thought due to the presence of peptone. He found that the filtrate of the 

 boiled venom solution (in water) is acid and forms coagula by neutralization. 



Peptone: Wolfenden employed the method devised by Hofmeister for 

 testing peptone: (i) Cobra venom which had been precipitated by satura- 

 tion with MgSO 4 was treated according to that method. 1 On addition 

 of the acid phosphotungstate of soda there was produced a slight opalescence. 

 (2) An alcoholic extract of cobra venom was treated with the above method 

 and gave similar opalescence with phosphotungstate of soda. The extract 

 gave undoubted protein reaction. (3) The dialysates (mixed) of cobra 

 venom, after 3 days' dialysis, gave no acid-albumin reaction, but yielded 

 precipitation with Hofmeister's method. Biuret was negative. (4) A portion 

 of cobra venom which was once treated with MgSO 4 and Na 2 SO 4 gave a 

 slight turbidity with the acid phosphotungstate of soda. From these experi- 

 ments Wolfenden concludes that there are three proteins present constantly 

 in cobra venom, namely, globulin, serum albumin, and syntonin and prob- 

 ably, in traces only, a fourth, peptone. 



Similar experimental studies have been extended by Wolfenden to the 

 venom of Daboia russellii. In this series for the separation of globulin he 

 employed precipitation by MgSO 4 , NaCl, and (NH 4 ) 2 SO 4 , CO 2 , and dialysis. 

 He found the globulin to coagulate at 75 C. The presence of serum albumin 

 was made apparent by precipitation of the magnesium filtrate by Na-jSO,, and 

 the occurrence in the solution of the soda precipitate of an opalescence on 

 boiling, within the range of coagulation temperature of serum albumin 

 70 to 80 C. 



1 Hofmeister's method is as follows : Treat a solution of albumin with saturated solution of sodic acetate 

 and then add ferric chloride, until of a blood-red color. At this point the addition of the ir on 

 is stopped. Neutralize it with sodium hydrate up to a slight acid reaction. Then boil the 

 fluid for a few minutes, and filter. The colorless filtrate must not give precipitate with ace tic 

 acid and ferrocyanide. Make the filtrate acid with acetic acid and test with an acid solution of 

 phosphotungstate of soda (acidified with acetic acid). The ratio of the filtrate and the 

 reagent is 4:1. If any peptone is present there is a flaky precipitate, or a turbidity, on 

 standing for a few minutes. All the albumins except peptone are removed by the ferric 

 acetate. This method is about 50 times'more accurate than that of biuret, which can detect only 

 in i: 2000. 



