Proteolytic Enzyme in the Latex from the Fig Tree (Ficus Glabrata). The pH of Optimal Activity. ∗

Abstract

For many years the sap from various species of the fig tree (genus Ficus) has been used in Central and South America as a vermifuge. 1 , 2 It has been shown to have a fair action against Ascaris and Trichuris trichiura. 3 We 4 found that the active anthelmintic principle was a protcolytic enzyme that was active over a pH range of 4 to 9 and that it would hydrolyze coagulated egg albumen, gelatin and casein. From the hydrolysis of casein, crystals of tyrosine and ‘leucine balls' separate out. Dilute solutions of the sap (0.5 to 1%) will digest the body walls and organs of live Ascaris.

The present paper gives the results of studies on the influence of different hydrogen-ion concentrations upon the proteolytic activity of the enzyme as determined by its action on gelatin.

Preparation of the dry enzyme mixture. The crude sap, a thick creamy mixture, contains about 25% solids, a part of which can be separated by centrifuging (this part is inactive); the remaining or active material is precipitated by 3 parts of acetone and is separated by decanting and centrifuging. The active part is redissolved in water and again precipitated by acetone and dried over CaCl₂ in a vacuum desiccator. One hundred cc. of the sap yields about 10–12 gm. of the dried powder to which we have given the name Ficin, from the generic name of the trees from which the active sap is obtained.

For determining quantitatively the enzymatic action on gelatin the formol titration was used. To 100 cc. of a 2% gelatin solution is added the sample of enzyme under study. A formol titration is carried out immediately on a 20 cc. aliquot. The mixture is then incubated at 35° for 24 hours and a second titration made. The difference between the 2 determinations is due to the hydrolysis and is proportional to the activity of the enzyme. Toluene was used as a preservative. The results are reported in milligrams of amino nitrogen set free by the action of the enzyme upon 100 cc. of 2% gelatin in 24 hours at 35°C.