1915] 



DAVIS — ENZYME ACTION IN MARINE ALGAE 813 



plainable on the ground that the casein gave rise to a slight 

 acidity. 



Specificity of action might explain the failure to obtain 

 action on most of the esters. Euler ('12) differentiates the 

 lipases into true lipases and esterases, the former acting on 

 neutral fats particularly, the latter on the methyl and ethyl 

 esters of the lower fatty acids. Even in this latter restricted 

 field, great specificity may be shown. Eeed ('12) found that 

 ethyl acetate was quite rapidly acted upon by an esterase 

 isolated from Glomerella rufomaculans, while ethyl butyrate 

 was only slightly hydrolysed. 



THE PROTEINASES 



The proteolytic activity of the various algae was tested on 

 albumin, casein, legumin, peptone, gelatin, and in certain 

 cases, on proteins isolated from the algal tissue — most of 

 these under acid, alkaline, and neutral conditions. The first 

 four were made up in 1 per cent concentrations. Albumin 

 and peptone went into solution quite readily; legumin and 

 casein, being insoluble in water, were either weighed out 

 directly, or dissolved in N/10 NaOH. The albumin and 

 gelatin were also tested in the form of Mett 's tubes, and the 

 gelatin alone in test-tubes where it was held at a temperature 

 high enough to keep it in a liquid state while in contact with 

 the algal powder. In all cases, algal tissue was used directly, 

 either fresh crushed, or dry powdered — usually 2 grams of 



the powder or 5 grams of the fresh tissue to each 50 cc. of 

 substrate. 



Determination of hydrolysis. — Proteolytic action was de- 

 termined in several ways, each acting as a check on the others. 

 The biuret test was used for the demonstration of tryptic 

 action, the proteins being precipitated by (NBU^SC^ in 

 saturated solution and the test applied in the usual way. The 

 tryptophane test was employed for ereptic action and this 

 also furnished a check on the action of trypsin. In this, 1 cc. 

 of the protein solution was placed in a small evaporating dish, 

 a drop of glacial acetic acid added, and then a few drops of 



to 



water. The hydrolysis to the amino acid sta 



