Mendel and Underhill — Papain- digestion. V 



with frequent agitation of the mixture for four hours, it was stopped 

 by heating, and the undissolved residue filtered upon dried and 

 weighed ash-free papers, then thoroughly washed with hot water 

 and dried to constant weight at 105° C. From the figures thus 

 obtained the percentage of proteid dissolved was calculated. The 

 results are tabulated below. 



PAPAIN DIGESTION OF COAGULATED EGG-ALBUMIN. 



(The figures indicate the percentages of proteid dissolved.) 



In evidence of the statement already made regarding the activity 

 of papain preparations in both alkaline and acid media, we might 

 add many additional data. In numerous qualitative tests with vari- 

 ous papain preparations acting on fibrin, casein, boiled and unboiled 

 muscle tissue, in the presence of 2 per cent. NaF and in media 

 acid with 0.1 per cent. IIC1, or alkaline with 1.0 per cent. HNaCO s 

 or 0.5 per cent. Na a C0 3 , or in approximately neutral fluids, vigorous 

 solvent action was always observed. In considering the relatively 

 weak digestive action noted above in the case of the acid mixtures, 

 it should be borne in mind that the strength of acid here recorded is 

 rather large 1 and by a selection of more appropriate conditions the 

 solvent power could doubtless have been considerably increased. 



II. Are Leucin, Ty rosin and Tryptophan formed by Papain? 



When trypsin acts upon ordinary proteids, leucin, tyrosin and 

 tryptophan (proteinochromogen) are speedily formed in considerable 

 quantities. These compounds do not arise in appreciable amounts in 

 pepsin- IIC1 digestion under ordinary circumstances, although some 

 recent experimental work leads to the conclusion that relatively 

 simple bodies (including leucin) may occur in prolonged proteolysis 

 with pepsin. Thus Lawrow 2 found large quantities of leucin 

 formed by the self-digestion of 1 2 kilos of pigs' stomachs with 35 



1 Cf. Chittenden: Transactions of the Connecticut Academy of Arts and 

 Sciences, 1892, ix, p. 307. 



2 Lawrow : Zeitschrift fiir physiologisehe Chemie, 1899, xxvi, p. 513. 



