RECENT WORK IN AGRICULTURAL SCIENCE 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



General chemistry of the enzyms, H. Eulek, traus. by T. II. Pope (Neto 

 York and London, 1912, pp. IX-\-323, figs. 7). — This is a translation of the 

 revised and enlarged German edition of this work, which has been previously 

 noted (E. S. K., 24. p. GOS). 



In regard to the action and regeneration of proteolytic enzyms, N. N. 

 IwANOFF (Trudy Imp. S. Peterh. Ohshch. Estestvo. (Trav. Sac. Imp. Nat. St. 

 Petersh.), JtS {1912), I, No. 2-8, pp. 95-106, 128).— It has been shown in previous 

 work (E. S. R., 27, p. 108) that KILPO* increases the capacity of the proteolytic 

 ferments in hefanol. Leuciu and tyrosin have no influence on this process. An 

 extract of hefanol was found to contain a proteolytic enzym. The action of 

 KH2PO4 manifests itself by the production of an excess of peptone during the 

 autolytic process. Adding KII^PO* to a watery extract of hefanol which had 

 been previously heated to from 75 to 80° C. or to gentle boiling produces a re- 

 generation of the enzym peptase. 



Studies on enzym action. — IV, Note on the occurrence of a urease in 

 castor beans, K. G. Falk (Jour. Amer. Chem. Soc, 35 (1913), No. 3, pp. 292- 

 294). — The work, which continues that previously noted (E. S. R., 29, p. 713), 

 indicates that castor beans contain a urease which is inactivated by heat in an 

 aqueous solution or suspension. 



Studies on enzym action. — V, The action of neutral salts on the activity 

 of castor bean lipase, K. G. Falk (Jour. Amer. Chem. Soc., 35 (1913), No. 5, 

 pp. 601-616). — In this work, which is a continuation of that noted above, " the 

 actions of neutral salts of the uni-univalent types, [the chlorids, iodids. fluorids, 

 nitrates of sodium and potassium, potassium bromid, lithium chlorid, lithium 

 nitrate, and sodium acetate], and the uni-bi- and bi-bivalent types, [the chlorids 

 and nitrates of barium, calcium, and magnesium, sodium sulphate, potassium 

 sulphate, sodium oxalate, manganous chlorid, manganous sulphate, and magne- 

 sium sulphate], were tested on the activity of a castor bean lipase preparation 

 toward ethyl butyrate under comparable conditions. In every case the change 

 in activity, whether increase or decrease, was found to be a continuous function 

 of the concentration of the salt added. Decreased activities, as compared with 

 aqueous solutions, were shown by all the uni-univalent salts, by the chlorids 

 and nitrates of barium and calcium (except for the most dilute solutions) and 

 magnesium, by sodium oxalate, and by dilute solutions of sodium sulphate. 



"Increased activities were shown by dilute solutions of the chlorids of barium 

 and calcium, by more concentrated solutions of sodium sulphate, by magnesium 

 bulphate, and by the chlorid and sulphate of manganese. Potassium sulphate 

 solutions gave the same results as purely aqueous solutions. ... If an ex- 

 planation of the retarding actions of the various salts be looked for, it may per- 

 haps be found in the coagulation of the enzym (either alone or together with 

 other substances) by the addition of the salts, the ions of which produce their 



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