vii OXIDATION-PRODUCTS 249 



percentage composition is concerned, and that their sulphur values 

 in particular agree closely. 



" Whether the higher percentage value of oxygen is really due to an 

 oxidation, or whether it is due to the carbohydrate radical becoming 

 more pronounced because of the diminution in the size of the mole- 

 cule, is as yet an open question." 



OXYPROTEIN 



Following up the older and neglected investigations of Chandelon l 

 and Wurster, 2 Schulz 3 has treated crystallised egg-albumin with 

 hydrogen-peroxide. He obtained a body which he calls ' oxyprotein.' 

 When proteid is oxidised in acid or in alkaline solutions it is dis- 

 sociated. On p. 93 it has already been stated that Neuberg found 

 amino-acids to have been converted into acetaldehyde and isovaler- 

 aldehyde. No such change was induced, however, when Schulz 

 oxidised in strictly neutral solutions. On adding an excess of 

 hydrogen -peroxide, along with a little platinum black, to neutral 

 solutions of albumins, he noticed, after the lapse of some weeks if 

 he worked at the room temperature, or more quickly on warming 

 the mixture, that the whole of the albumin was deposited. This 

 .precipitate he called ' oxyprotein.' 



Apart from a higher percentage of oxygen, oxyprotein does not 

 differ from ordinary albumin ; it gives all the albumin -reactions, 

 inclusive of Millon's reaction and the sulphur test. This substance 

 is an acid which is insoluble in acids, water, or salt solutions, while it 

 is readily soluble in alkalies and alkali-carbonates. It is precipitated 

 from its solutions by acids, but only at first, for after having been kept 

 for some time in alkaline solutions it is only partly precipitable. It 

 differs from acid -albumin and many acid-proteids in being only 

 re -dissolved by a large excess of acid. The alkali -salts of oxy- 

 protein are further precipitated by small amounts of sodium chloride 

 and other neutral salts. It is non-coagulable. The alkaloidal 

 reagents precipitate it, but not so the salts of the heavy metals 

 copper and silver which may perhaps be due to an absence of neutral 

 salts. Alcohol does not precipitate the alkali-salt. 



Schulz believes therefore peroxide of hydrogen to produce really 

 only an oxidation of the albumin without any other changes, the 

 oxygen entering some indifferent group and rendering it acid. 



1 Chandelon, Ber. d. deutsch. diem. Ges. 17. (2143) (1884). 



2 C. Wurster, ibid. 2O. 263 (1887). 



3 F. N. Schulz, Zeitschr. f. physiol. Chem. 29. 86 (1899). (Here also the oldei 

 literature.) 



