1907.] 



Studies on Enzyme Action. 



355 



yeast, although the two extracts were almost equally active in hydrolysing 

 maltose. The maltase in the bottom yeast appears to have been somewhat 

 more resistant, a considerable proportion surviving in the extract which had 

 been heated to 50°. The extract prepared from this yeast at 25° was more 

 active than that prepared at a higher or lower temperature, 15° being the 

 most favourable temperature in the case of the English top yeast ; moreover, 

 the hydrolysis of maltose was best effected by this yeast at 35° instead of 

 at 25°. 



Eesults similar to those recorded in Table III were obtained with another 

 sample of yeast reported to be a bottom yeast grown in maize wort. 



In view of the high temperature at which it exerts its maximum fermen- 

 tative power, it appeared desirable to examine the remarkable yeast 

 & Thermantitonum described by Grove Johnson. Mr. Johnson was good 

 enough to give us some quantity of the yeast : unfortunately, the extract pre- 

 pared from it was so highly coloured that satisfactory measurements could not 

 be made with it. The impression was gained that it resembled that prepared 

 from the bottom yeast and that possibly amygdalin was not attacked by it. 



Eesults are recorded in Tables IY and V which finally led to the conclusion 

 that maltase can be entirely destroyed by heating, whilst the extract retains 

 its activity towards amygdalin almost unaltered. Owing to the greater 

 stability of the maltase in the case of the bottom yeast, it was necessary to 

 heat the extract during a longer period (three hours instead of one) in order 

 to render it inactive towards maltose. 



Table IV.- 



—Action of Extract of Top Yeast prepared at 15°. * 



G-lucoside used. 



Treatment of extract. 



Amount hydrolised 



at 25°. 



24 hours. 



48 hours. 



72 hours. 



Amygdalin 



[" Unheated 



< Heated at 45° (2 hours) ... 

 [ „ 50° (1 hour) 



fTJnheated 



J Heated at 45° (1 hour) 



] „ 45° (2 hours) ... 

 L „ 50° (1 hour) 



f Unheated 



per cent. 

 13-9 

 17*8 

 18-3 



65-8 



16-1 



1-5 



o-o 



60-9 

 16-5 

 15 



per cent. 

 21-7 



25-4 

 25-8 



76-4 



22-7 

 1-8 



o-o 



71-1 

 26-9 

 23-7 



per cent. 

 28-3 

 31-7 

 34-6 



79-1 



23-3 



1-8 



o-o 



75-1 

 32-5 

 29-3 



Maltose 



Methyl-o-glucoside 



< Heated at 45° (2 hours) ... 

 L „ 50° (1 hour) ... 



