p
w 4 h California Association of Chemistry Teachers
John L. Abernethvl and Gilbert L. Leonardo University of California, Davis and San Marcos University, Lima, Peru
1 Ficin
US
Occasionally an enzyme is desired for an undergraduate laboratory course or more particularly by a student launching a special problem in organic chemistry. For such a purpose, the enzyme ficin may be of interest. It is a proteolytio enzyme that catlyzes the synthesis of compounds containing amide or amidelike bonds. By appropriate selection, a clean-cut synthesis of a solid product can be brought about in good yield and it is readily purified by application of familiar principles. Ficin is dispensed by a number of commercial houses in the U.S.= as a solid, tan powder that is very stable if kept dry and cold. I t is imported from South America. Unlike raw, dried, papain, which needs activation, usually by prolonged treatment with hydrogen sulfide, ficin does not require activation. It is readily soluble in water and requires about 0.51.0 g per 100 ml of solution to carry out an appropriate synthesis. Syntheses can be chosen that demonstrate considerably more than mere formation of compounds. Ficin is isolated from latex of Ficus trees. The viscous fluid secreted at the stems of the fruit of Ficus carica trees, which are domestic figs, contains the enzyme to the extent of about 10% by weight (I). The industrial source of solid ficin, however, is the
' Fulbright Fellow in Chemistry, Uuiversidad Nacional de San CrisMhal de Huamanga, Ayacucho, Peni, and Univeraidsd Nacianal Mayor de San Marcos, Lima, Peni, 1962-63. Present address: Department of Pomology, University of California, Davis. I t is appropriate to express the following aeknowledgementa: Dr. Edumdo F. Indscaehes, Executive Secretary of the Fulhright Commission in Lima, Perd, provided many necessary contacts. Also, an assistant, Mr. Gilbert Leiva Leonarda, wss financed by Fulhright funds. The Los Angeles County Heart Association made available Research Grant 309. Dried fiein enzyme was donated by Mr. Roberto Power, Manager, Astoria Compaiiia, Iquitos, Peru, and hy Director Oliverio Phillips M., Instituto de Investigaciones Teenol6gicas, Bogat&, Colombia. Other assistance was given hy Dean Manuel Mom Sommo and Dr. Bertha Pareja, San Marcos University, Lima, Perd. Rector Efrain Morote Best and Ingeniero Victor Montenegro, University of Huamanga, Peni,. gave other important . . Ayacucho, . assistance. %Forexample, The California Corporation for Biochemical Researoh, 3625 Medford Street, Los Angeles 63, California; Paul-Lewis Laboratories, Inc., 4215 North Port Washington Avenue, Milwaukee 12, Wisconsin; or General Biochemicals, 700 Laboratory Park, Chagrin Falls, Ohio.
a Catalyst in Organic Syntheses
abundant latex of huge Ficus anthelmentica and Ficus glabrala trees of the Amazon basin of South America.
From two to ten gallons of latex can be obtained from a tree in a single day. I t is preserved by addition of 0.02% by weight of acetic acid, then subjected to pressure filtration after addition of 10yo by weight of infusorial earth. The clear liquid is subsequently spray-dried to a tan powder and hermeticaly sealed to protect from moisture. A student can secure dried enzyme directly from the Compafiia Astoria, Iquitos, Perh, or from the Instituto de Investigaciones Tecnol6gicas, Bogot6, Colombia. It retains its activity for several years if stored in a plastic bag, inside a brown bottle with a screw cap kept in a refrigerator. Catalytic Behavior
Ficin contains a mercapto group, -SH, a t its active site, which in part explains its similarity in catalytic behavior to papain from green papaya fruit, bromelin from pineapple juice, and bromelain from stalks of mature pineapple plants. Undoubtedly, the variety of synthetic reactions catalyzed by ficin will prove to be as great as when papain is employed as the enzyme (2). A few extensions of ficin-catalyzed syntheses have been those between benzenesulfonhydrazide (3) and the familiar soluble, acylated amino acids: hippuric acid, carbobenzoxyglycine, carhobeozoxy-L-alanine, and carbobenzoxy-~balanine. 0 H II I
C,;Hi-CH,-0-C-N-CH-C-OH I
0 II
O H H
H
+
H-N
O H
CH.; Carbobenzoxy-balanine hydroxyanilide
The experiments used for illustration involve reactions between the three soluble acylated amino acids, hippuric acid, carbobenzoxy:bahnine, and carbobenzoxy-DL-alanine and each of the o-, m- and pVolume 41, 1 , January 1964
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