1903.] 



On the Nucleoproteids of the Pancreas, etc. 



391 



B. Nuclein accompanying, and probably resulting from, the NucleoproteicL 

 Method of Preparation. 



The aqueous extract of the purified gland substance to which 

 acetic acid had been added until it contained 1 per cent, of the 

 latter, and from which the nucleoproteicl had thus been separated, was 

 treated with 20 per cent, acetic acid added a drop at a time. "When 

 the liquid contained 2 per cent, of the acid not the slightest precipita- 

 tion had occurred. Continued addition of acetic acid, however, soon 

 caused a turbidity, and when the acidity reached 5 — 6 per cent., a 

 well-defined flocculent precipitate fell. This precipitate, which we 

 shall call nuclein, was separated by means of the centrifuge and, at a 

 great cost of material, was twice washed with water, the washings 

 being separated by centrifugalising. The washed nuclein was suspended 

 in water, and solution of ammonia added cautiously, one drop at a 

 time ; when the nuclein was completely dissolved, the reaction of the 

 liquid was still acid to litmus. This solution was poured into four 

 volumes of 95 per cent, alcohol, and the precipitated nuclein washed and 

 dried by the methods described in the case of the nucleoproteicl. 



The fluid from which the "nuclein "had been precipitated, as has 

 been stated, was now poured into four volumes of alcohol, and the 

 precipitate thus thrown down was washed and dehydrated by the 

 action of alcohol and ether. This preparation, which is necessarily 

 very impure and especially rich in organic salts, will be described and 

 referred to as " residual material." 



Thus, by fractional precipitation with acetic acid, in the presence of 

 inorganic salts, we have obtained three preparations. The nucleo- 

 proteid, which is doubtless the body which Hammarsten denominated 

 Proteid-a, is almost insoluble in pure water, but may be dissolved by 

 minute quantities of ammonia and caustic soda. The body which we 

 have termed nuclein, to indicate our opinion of its relation to the first 

 substance, is soluble in water with the greatest ease. 



By the addition of a trace of copper sulphate to a solution of the 

 nucleoproteid in caustic soda a fine pink colour is produced, but not a 

 shade of violet makes its appearance until a comparatively large amount 

 of copper solution has been added, a reaction which resembles closely 

 " the biuret reaction " with the proteoses. The " nuclein " by similar 

 treatment gives only the faintest pink colour, the violet shade being 

 observed even when a very small amount of copper sulphate is used, 

 while the " residual material " produces a violet colour from the 

 beginning. 



It has recently been shown by one of us* that the nucleoproteid of 



* W alter Jones and Gr. H. Whipple, " The jSTucleoproteid of the Suprarenal 

 Gland," ' Amer. Jour, of Phys.,' vol. 7 (1902), p. 423. 



