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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 = kVpt where A; is a constant, p the quantity of enzyme and t the time
of the action. This was first _shown by Schutz * for pepsin and also,
in this form, decomposition =kvp as the time (t) was constant. The form
decomposition =fcv pt was given by Schutz, and Huppert. 2
According to
Pawlow this rule also applies to trypsin digestion. 3
Schutz’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.
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 l0
yeast-press juice has
the power of forming glycogen from glucose or fructose.
1
Zeitschr. f. physiol. Chem., 9, 577 (1885).
2
Pfliiger’s Arch., 80, 470 (1900).
3
Arbeit der Verdauungsdriisen, Wiesbaden, 1898, 33.
•
Stade, Hofrneister’s Beitrage, 3, 318 (1903); Engel, ibid., 7, 77 (1906), see Fromme,
ibid., 7, 77, (1906).
5
Immunochemie, 1907, 43.
6
Journ. of chem. Soc, 73, 634 (1S98).
>
Ber. d. d. chem. Gesellsch., 34, 600 and 2207 (1901).
8
Proc. Roy. Soc. (ser. B), 76, 592, (1905)
’ Her. d. d. chem. Gesellsch., 35, 3151, (1902).
’"Ibid., 32, 2062 (1899).
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