82 THE PROTEIN SUBSTANCES. 



By the oxidation of protein by means of potassium permanganate, MALY 

 obtained an acid, oxyprotosulphonic acid, C 51.21, H 6.89, N 14.59 S 1.77, O 25.54 

 per cent, which is not a cleavage product, but an oxidation product in which 

 the group SH is changed into SO 2 .OH. This acid does not give the proper color 

 reaction with MILLON'S reagent, yields no tyrosine or indol, but gives benzene 

 on fusing with alkali. On continued oxidation MALY obtained another acid, 

 peroxyproteic acid, which gives the biuret reaction, but is not precipitated by 

 most protein precipitants. The oxyprotein obtained by SCHULZ on the oxida- 

 tion of protein by hydrogen peroxide is closely related to oxyprotosulphonic 

 acid in composition and general characteristics, but contains lead-blackening 

 sulphur and gives MILLON'S reaction. The oxyprotein is claimed to be a pure 

 oxidation product, while in the production of oxyprotosulphonic acid SCHULZ* 

 claims that a cleavage takes place. According to the recent investigations of 

 v. FuRTH 1 there exist at least three different peroxyproteic acids (from casein) 

 which differ from each other by a different division of the nitrogen in the mole- 

 cule. On treatment with baryta- water we find that they split off basic complexes 

 and oxalic-acid groups, and new bodies, the desaminoproteic acids, which give 

 the biuret reaction, are produced. These acids, which on hydrolysis give benzoic 

 acid but no diamino-acids, may be further oxidized, which is "not true of the 

 peroxyproteic acids, and yield a new group of acids, the kyroproteic acids, which 

 give the biuret reaction, hold about one-half of their nitrogen (11.08 per cent 

 total nitrogen) in acid-amide-like combination, but yield neither basic products 

 nor benzoic acid. 



On the oxidation of gelatin or protein with permanganate we also obtain 

 oxaminic acid, oxamide, oxalic acid, oxaluric-acid amide, succinic acid, several 

 volatile fatty acids, and guanidine, which was first shown by LOSSEN as an oxida- 

 tion product (KUTSCHER, ZlCKGRAF, SUBMANN, KuTSCHER and SCHENCK). 2 



On the oxidation of gelatin by ferrous sulphate and hydrogen peroxide 

 BLUMENTHAL and NEUBERG have obtained acetone as a product, and ORGLER 

 the same from ovalbumin. By the action of ozone upon casein, HARRIES and 

 LANGHELD 3 found neither phenyl alanine nor tyrosine among the cleavage 

 products, which fact they explain by the destructive action of the ozone upon the 

 aromatic nucleus. Besides this, reducing bodies w r hich are not carbohydrates, but 

 which react with phenylhydrazine, are produced. JOLLES 4 claims to have obtained 

 large quantities of urea in the oxidation of various proteins by potassium per- 

 manganate in acid solution, but this has been disputed by other investigators 

 and the above statements in regard to the oxidation products of proteins are of 

 little interest. 



Nitric acid gives various nitro-products such as trinitroalbumin, oxynitro- 

 albumin, xanthoprotein and others. A melanoidin substance, xanthomelanin, 

 has been obtained by v. FURTH. 5 HABERMANN and EHRENFELD 6 also obtained 

 oxyglutaric acid among other products. By the action of bromine under 

 strong pressure a number of products have been obtained: bromanil and 

 tribromacetic acid, bromoform, leucinimide, leucine, oxalic acid, tribromamino- 



1 Maly, Sitzungsber. d. k. Akad. d. Wissensch., Wien, 91 and 97. Also Monatshefte 

 f. Chem., 6 and 9. See also Bondzynski and Zoja, Zeitschr. f. physiol. Chem., 19; 

 Bernert, ibid., 26; Schulz, ibid., 29; v. Fiirth, Hofmeister's Beitrage, 6. 



2 Lessen, Annal. d. Chem. u. Pharm., 201; Kutscher, Zeitschr. f. physiol. Chem., 

 32; Zickgraf, ibid., 41; Seemann, ibid., 44; Kutscher and Schenck, Ber. d. d. chem. 

 Gesellsch., 37 and 38. 



3 Blumenthal and Neuberg, Deutsch. med. Wochenschr., 1901; Orgler, Hofmeister's 

 Beitrage, 1; Harries and Langheld, Zeitschr. f. physiol. Chem., 51. 



4 Zeitschr. f . physiol. Chem., 32 and 38. 



5 See Maly's Jahresber., 30, 24. 



6 Zeitschr. f. physiol. Chem., 35. 



