AGRICULTURAL CHEMISTRY — AGROTECHNY. 803 



cylglyciu. maximum, though small, actions were obtained with etiiyl bntyrate, 

 very slight but distinct with olive oil, while with glycylleucin and diglycyl- 

 glycin and methyl acetate negative values were obtained. Not enough meas- 

 urements were made with the former to make this last result certain." 



The authors point out that despite the results obtainetl above there is no 

 evidence at hand that the hydrolysis of fats, etc., by lipase is due to amino 

 acids or polypeptide. 



A proteolytic enzym in the must of overripe grapes, E. Pantanelli 

 {Ccntbl. Bakt. [etc.]. ^. Ahi., 31 {1911), Xo. .iS-25. pp. 5.'f5-559 ; abs. in Zentbl. 

 Biochem. u. Biophys., 12 (1912), Xo. 19-20, p. 824).— The m»st of overripe 

 white and red grapes was found to contain an enzym which cleaves protein to 

 pmducts which are not precipitated by copper hydroxid. 



The use of elastin for detecting proteolytic enzyms, E. Abderhalden and 

 K. KiESKWETTKR ( Hopitp-Seijlf r'.s ZtHclir. Physiol. Chern.. 7 J (1911), Xo. .J-,5, 

 pp. .'ill-.yiH; aba. in Chem. Ahs.. 6 (1912), No. 8, p. iO/o).— Enzyms can be 

 demonstrated in feces, various organs, and press-juices from them with the 

 aid of elastin. A study made of the digestion of elastin and of native and 

 coagulated egg albumin by gastric juice and pepsin-hydrochlcrric acid with 

 the aid of the optical method indicated that the results obtained with gastric 

 juice and pepsin-hydrochloric acid are not at all comparable. 



The ferment nature of peroxidase, Gbimml-k (XliJrhw. Zentbl., Ifl il912), 

 y'o. 6, pp. 16.5-168). — Milk iiero.xidaso apparontly has nothing to do wilh the 

 alkalinity or the iuoi'ganic constituents of milk. Peroxidase is of an organic 

 nature and closoly associated with lactitlbuniin. 



Activation of sucrase by various acids, G. Bektrand and M. and Mme. M. 

 Rosenblatt (Conipt. Rend. Acad. 8ci. [Paris], 163 (1911), No. 26, pp. 1515- 

 1318; abs. in Zentbl. Biochem. u. Biophys., IS (1912), No. .). p. 167).— The 

 action of a large number of acids and acid salts was studied as regards their 

 power of accelerating the activity of sucrase (invertase), and with particular 

 reference to the optimum concentration of these acids. 



The chemical constitution of the proteins, R. H. A. Plimmee CSew York, 

 Bombay, and Calcutta, 1912, 2. cd.. pt. 1 pp. XII+188, figs. 6). — In this second 

 edition (E. S. R., 21. p. 210) a more detailed analysis of the proteins is given. 



The precipitation of proteins by zinc sulphate, F. Lippich (Hoppe-Seyler's 

 Ztschr. Physiol. Chem., 7.'f (1911), No. Jf-5, pp. 360-391; abs. in Chem. Abs., 

 6 (1912), No. 8, p. 1010). — "When protein is precipitated by increasing con- 

 centrations of zinc sulphate, there are 2 maxima of precipitation, the first 

 beginning at 0.08 to 0.1 normal, the sec-ond at l.S to 2 normal; between lies a 

 minimum at which the liquid remains for a time clear. Equal volumes (5 to 

 10 cc.) of diluted horse serum were treated with graduated amounts fO.l to 1 

 cc.) of a saturated solution of zinc sulphate, and made up to a round volume 

 (50 to 200 cc). .The conditions corresponded to rapid equilibrium at the lower 

 maximum. The precipitates contained, independently of the concentration of 

 protein and the original concentration of zinc sulphate, always the same amount 

 of zinc. The capacity of the protein to combine with zinc apparently increases 

 with the dilution; that the zinc precipitated per unit volume remains the same 

 seems to indicate a combination in constant proportions. The precipitations 

 produced at the second maximum contain about twice as much zinc. The 

 results are difficult to reconcile with the absorption hypothesis. They suggest 

 rather a balanced reaction according to the scheme: ZnS04+2Na protein<:::± 

 Na2S04 4-Zn (protein)-. Most of the facts can be explained by the further 

 assumption that, as salt concentration and other conditions vary, there arise 

 such types of compound as ZnS04, protein; Zn, protein, — ZnSd; and Zn, 

 protein." 



