58 GENERAL AND PHYSICO-CHEMICAL. 



In determining the quantity of enzyme the so-called SCHUTZ'S rule plays 

 an important part. In its newest form this is, that the decomposition is pro- 

 portional to the square root of the quantity of enzyme and the time, or decom- 

 position =k\/pt where fc is a constant, p the quantity of enzyme and t the time 

 of the action. This was first _shown by SCHUTZ 1 for pepsin and also, 

 in this form, decomposition =k\p as the time (t) was constant. The form 

 decomposition = k \/pt was given by SCHUTZ, and HuppERT. 2 According to 

 PAWLOW this rule also applies to trypsin digestion. 3 SCHUTZ 7 s rule is good for 

 a certain stage of digestion only and it indicates that the extent of the validity 

 must be very dependent upon the method used for the determination of the 

 decomposition as the different digestion products are determined by different 

 methods. It must also be remarked that within the entire domain where 

 SCHUTZ'S rule is applicable the same value for pt must correspond to the same 

 decomposition, and necessarily the above-discussed enzyme-time rule must also 

 be valid. SCHUTZ'S rule has also been proved for the action of gastric and pan- 

 creatic lipase. 4 According to ARRHENIUS 5 the validity of the rule can be explained 

 by the assumption that the enzyme combines with the reaction products so that 

 the active mass of enzyme changes in inverse proportion to the auantity of 

 reaction products. 



K Reversibility of Enzyme Action and Enzymotic Syntheses. Many 

 catalytic processes have been shown to be reversible, i.e., the same 

 catalyst can influence the reaction in different directions according to 

 the concentration of the substances present. Thus far we have only 

 spoken of enzymotic cleavages; according to the above it is to be expected 

 that synthetical processes can also be produced by enzymes. 



The first example of such a reaction was given by CROFT-HILL . 6 

 He treated a 40 per cent glucose solution with maltase at 30 C. for a 

 very long time and concluded from the change in rotation and reducing 

 power that some maltose was formed from the glucose. EMMERLING 7 

 showed afterward that a synthesis of maltose did not occur, but rather 

 an isomeric carbohydrate, isomaltose was formed, which is not split by 

 maltase. According to ARMSTRONG 8 emulsin splits isomaltose, but 

 not maltose, and therefore it can synthesize maltose from glucose. A 

 similar reaction had previously been shown by E. FISCHER and ARM- 

 STRONG, 9 that kefir-lactase produced isolactose and not lactose from 

 galactose and glucose. According to CREMER 10 yeast-press juice has 

 the power of forming glycogen from glucose or fructose. 



1 Zeitschr. f. physiol. Chem., 9, 577 (1885). 

 'Pfliiger's Arch., 80, 470 (1900). 



8 Arbeit der Verdauungsdrusen, Wiesbaden, 1898, 33. 



4 Stade, Hofmeister's Beitrage, 3, 318 (1903); Engel, ibid., 7, 77 (1906), see Fromme, 

 ibid., 7, 77, (1906). 



6 Immunochemie, 1907, 43. 



6 Journ. of chem. Soc., 73, 634 (1898). 



7 Ber. d. d. chem. Gesellsch., 34, 600 and 2207 (1901). . 

 "Proc. Roy. Soc. (ser. B), 76, 592, (1905) 



9 Ber. d. d. chem. Gesellsch., 35, 3151, (1902). 



., 32, 2062(1899). 



