LIPASE 75 



is the conversion of the fat into carbohydrate, the reverse 

 to what obtains during the maturation of the seed. The 

 change is effected by the activity of lipase which hydrolyses 

 the fat into glycerol and fatty acid. 



The work of Ivanow has shown that lipase has a reversible 

 action, and whether it hydrolyses or synthesizes fats is merely 

 a question of conditions, mainly the presence or absence of 

 water. The glycerol extract of a fat-containing seed, which 

 extract contains the lipase, mixed with oleic acid will synthe- 

 size a fat : the addition of water will result in the hydrolysis 

 of this fat into glycerol and fatty acid. 



In the synthesis of fats, Ivanow considers that higher 

 saturated acids of the fatty series are the first to be formed 

 from the sugar, and these are converted into unsaturated acids 

 which combine with the glycerol to form the fat. 



With regard to the origin of glycerol, the chemical relation- 

 ship between this substance and glucose is so close as to suggest 

 at once the possible inter-relation of the two ; further, glycerol 

 may have an origin in respiratory processes as is shown by the 

 production of this substance during the alcoholic fermentation 

 of sugar. 



Maclean and Hoffert * have studied the formation of fat 

 in Saccharomyces. When yeast is incubated in oxygenated 

 water, part of the reserve carbohydrate disappears and the 

 amount of fat increases. This change does not take place if 

 the yeast is grown in M/io oxygenated solutions of propyl, 

 butyl and isoamyl alcohols, but does happen when the plant 

 is incubated in M/io solutions of sodium formate, sodium 

 propionate, sodium butyrate, glycerol and acetone. When 

 cultivated in 5 per cent, solutions of ethyl alcohol, sodium 

 acetate, sodium lactate or sodium pyruvate, an increase in 

 the amount of fat occurs similar to that effected by a 0-5 

 per cent, solution of glucose, but this amount of fat is not 

 further increased by the higher concentration of the substances 

 mentioned. In sugar solutions, on the other hand, the cells 

 incubated in oxygenated solutions store up fat, in addition 



* Maclean and Hoffert : " Biochem. Journ.," 1923, 17, 720. See also 

 Maclean : id., 1922, 16, 370. 



