CHAP. III.] PHYSICAL AND CHEMICAL PROPERTIES OF LEUCINE. 241 



Leucine is, when pure, soluble in approximately 1040 parts of 

 absolute (98 per cent.) alcohol at ordinary temperatures, and 800 

 parts of boiling alcohol of the same strength (Zollikofer, B. Gmelin). 

 Leucine is insoluble in ether. It is dissolved by alkalies and acids. 

 Impure leucine is, however, much more soluble both in water and 

 alcohol than the pure substance. 



Rotatory Leucine which is the product of the action of 



trypsin on albuminous and albuminoid bodies, or which 

 is obtained by decomposing the proteids by means of acids, is dex- 

 trogyrous. Its specific rotatory power (a) D = + 17 '3 (Schulze 

 and Bosshard 2 ). In a remarkable investigation, Professor Schulze, 

 with whom were associated E. Bosshard and (in a great part of the 

 work) J. Barbieri 1 2 , discovered, in the first place, that leucine which 

 is obtained by the action of barium hydrate on the proteids at 

 high temperatures (150 160 C.) is inactive. They next proved 

 that when normal, optically active leucine is heated with barium 

 hydrate to 150 160 it acquires the properties of the body obtained 

 by the action of the same reagent acting on the proteids at the same 

 temperature. The optically inactive leucine was found to be less 

 soluble in water than normal leucine, requiring about 100 parts of 

 rater at ordinary temperatures for solution. 



The next remarkable discovery consisted in proving that when 

 Penicillium glaucum is sown in a suitable sterilised culture fluid to 

 which optically inactive leucine has been added, and the organism 

 illowed to develope for some weeks, an optically active leucine is 

 it last found in solution, but this differs from the normal leucine in 

 iing laevogyrous. Whilst for normal leucine (a) D = + 17'3, for leu- 

 cine formed under the action of Penicillium glaucum (a) D = 17'5. 



Reasoning by analogy, we should assume that under the influence 

 of a high temperature two physically isomeric leucines are formed, one 

 of which (the normal) is dextrogyrous, and the other Isevogyrous; 

 further, that the mould which effected the wonderful transformation 

 consumed one of the isomers, viz. the dextrogyrous leucine, leaving its 

 Isevogyrous fellow untouched. In accordance with these probable 

 assumptions, Schulze and Bosshard found that the amount of laevo- 

 gyrous leucine recovered amounted approximately to one-half the 

 weight of the inactive leucine which had been acted upon by the 

 Penicillium, and, further, that after the process had been approxi- 

 mately completed, so that but very little inactive leucine could be 

 present in the solution, freshly introduced Penicillium developed very 

 scantily. 



It will be seen in the sequel that other amido-acids possess, like 

 



1 E. Schulze (unter Betheiligung von J. Barbieri und E. Bosshard ausgefithrt), 

 1 Untersuchungen uber die Amidosauren, welche bei der Zersetzung der Eiweissstoffe 

 durch Salzsaure entstehen,' Zeitschrift f. physiol. Chem., Vol. ix. (1885), pp. 63144. 



2 Schulze and E. Bosshard, 'Untersuchungen iiber die Amidosauren, &c.' 

 Zeitschrift f. phys. Chem., Vol. x. (1886), pp. 134145. 



G. 16 



