60 THE FORMATION OF PROTEIDS IN PLANT-CELLS. 



the presence of a digesting ferment, resembling trypsin, in plants, 

 to which he ascribed the production of amido-acids from proteids. 1 ' 



If we compare now the quantities of the different amido- 

 acids and bases with that of asparagin we find generally the 

 latter present in larger quantity, although the decomposition of 

 proteids by enzymes or by mineral acids yields only relatively small 

 quantities of aspartic acid (which in the plant-cells might easily 

 be transformed into asparagin). While 100 parts of conglutin 

 (the principal reserve protein in lupins) yield upon decomposition 

 with hydrochloric acid 6 parts of glutaminic acid, 1,5 parts of 

 aspartic acid, 10 parts of leucin and 2 parts of tyrosin, we find in 

 lupin-shoots 12 days old, the asparagin in dominating quantities, 

 amounting to almost 30 per cent of the dry substance, while 

 tyrosin was found only in traces and glutamin could not be found 

 with certainty. Instead of leucin the next lower homologue 

 (perhaps produced from the former by oxidation), was found. 4) 

 The germinating seeds of Cucurbita contain only a very small 

 amount of leucin, but 1,75 per cent of glutamin and 0,06 per cent 

 of asparagin ; tyrosin amounted here to 0,25 per cent. 



According to Ritthausen gluten-casein yields on decompo- 

 sition with hydrochloric acid 0,3% aspartic and 5,3% glutaminic 

 acid; legumin yields 3,5% of the former and 1,5 % of the latter 

 (only mucedin yields larger quantities of glutaminic acid, 

 viz. 25%). Still - we find in plants generally asparagin as 

 the main product, 3) the other amido-compounds disappearing 

 rapidly again and being found only in relatively small quantities. 

 Schulze supposed that the decomposition of protein in plants 

 would yield the same products and in the same quantities as 

 the decomposition by trypsin or by acids, but that the rege- 

 neration of proteids would proceed more easily from the 

 other amido-compounds than from aspartic acid, hence the 

 latter — transformed into asparagin — must accumulate. 4 ' This is, 



1) Ber. Deutsch. Chem. Ges. Vol. 7 and 10. 



2) E. Schulze and Barbieri, Landw. Jahrb. 1880, p. 18. Most proteids yield by 

 decomposition with acids more than 20 per cent leucin . 



3) In certain cases mentioned above, asparagin is found replaced by its next 

 homologue, glutamin. This might he gradually transformed into the former in the 

 plant-cells or like asparagin serve in the regeneration of certain proteids. 



4) Other views upon this subject were discussed by E< Schulze in Landw. Jahrb. 

 Vol. 17 and 21. — He showed that they are either incorrect or imperfect. 



