THE NUCLEO-PROTEIDS 



461 



5. The Nudeo-Proteid of the Gastric Juice 



Pekelharing, 1 Schumow-Simonowsky, 2 and Nencki and Sieber 3 

 found a nucleo-proteid not only in extracts of the gastric mucous 

 membrane, but also in pure gastric juice prepared by Pawlow's 

 method. Analysis gave these figures : 



The preparations were, however, not quite pure. The proteid is 

 soluble in water and in strong hydrochloric acid, but insoluble in very 

 dilute hydrochloric acid. It is therefore precipitated by dialysing 

 gastric juice, and may be readily obtained pure by this means or by 

 salting out with ammonium sulphate. When heated it breaks up into 

 a nuclein and a substance resembling albumose. On standing it 

 decomposes, there being formed peptones. Pekelharing and Nencki 

 and Sieber believe this nucleo-proteid to be pepsin, but Glassner's 4 

 work throws some doubt on this interpretation. Amongst its dissocia- 

 tion-products Pekelharing found xanthin and a pentose. The proteid 

 gives the ordinary albumin-tests. 



6. The Nucleo-Proteid of the Thyroid 



Oswald 5 prepared it from the thyroid of the sheep. It contains 

 O'l 6 per cent phosphorus. Its coagulation-temperature is 73. It is 

 insoluble in water, but soluble in salt-solutions and in alkalies. The 

 precipitation-limits for ammonium sulphate are 6 '4 and 8 '2. It is 

 precipitated by acids. When acted upon by pepsin and hydrochloric 

 acid it splits off a nuclein. On being dissociated it gives rise to 

 xanthin-bases and a carbohydrate which is not a pentose. It does 

 not contain iodine, and has nothing to do with the specific action of 

 the thyroid gland. 



1 C. A. Pekelharing, Zeiischr. /. physiol. Chem. 22. 233 (1896) ; 38. 8 (1902). 



2 0. 0. Schumow-Simonowsky, Arch. f. experiment. Pathol. und Pharmak. 33. 336 

 (1896). 



3 M. Nencki and N. Sieber, Zeitschr.f. physiol. Chem. 32. 291 (1901). 



4 K. Glassner, Hofmeister's Beitrage, 1. 1 (1901). 



5 A. Oswald, Zeitschr. f. physiol. Chem. 27- 14 (1899). 



