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ENZYMES. 57
The second law for catalytic reactions which we have formulated,
that with constant quantities <>f substrate the reaction velocity is pro-
portional to the quantity of enzyme, has been shown in certain cases
where the substrate was in excess (practically constant quantity) namely
with kephir lactase, 1
trypsin with casein as substrate.2
In the just-
mentioned inonomolecular enzyme reactions the velocity coefficient in
a few cases was found proportional to the quantity of enzyme (catalase
from blood,3
erepsin with glycyl-glyeine as substrate,4
pancreatic lipase 5
)
and in others not (catalase from Boletus scaber, lipase from pig fat).6
It has been shown for several enzymotic reactions that with the same
substrate the same decomposition can be obtained if the time of action
varies in inverse proportion to the added quantity of enzyme. If p is
the quantity of enzyme and t the time of action, then the decomposition
is the same in all tests where p.t is the same figure. This rule has been
found true for the following enzymes: saccharase (O’Sullivan and
Thompson as well as Hudson 7
), pepsin (Sjoqvist 8
), rennin (especially
Fuld 9
), peptone-splitting enzyme (Vernon 10
), fibrin ferment of snake
poison (Martin 11
), trypsin (Hedin 12
), pepsin, rennin, trypsin, pyocy-
aneus protease (Madsen 13
). On the action of trypsin upon casein this
law has been shown correct for different stages in the reaction. 14
This
indicates that the progress of the entire reaction remains the same with
different quantities of enzyme, only that the time for the same decom-
position is inversely as the quantity of enzyme. As clearly shown by
Hedin, this indicates that the velocity coefficient is proportional to the
quantity of enzyme which is called for by the second law. If we start
with the above-mentioned assumption that only that enzyme is active
which is combined, then it follows from the proportionality between the
velocity coefficient and the quantity of enzyme, that always the same
fraction of the enzyme is combined with the substrate, or that the divi-
sion of the enzyme remains independent of the quantity.
Armstrong, Proc. Roy. Soc, 73, 500 (1904).
2
Hedin, Journ. of Physiol., 32, 471 (1905).
3
Senter, Zeitschr. f. physik. Chem., 44, 257 (1903).
4
Euler, Zeitschr. f. physiol. Chem., 61, 213 (1907).
5
Kastle and Loevenhart, Amer. Chem. Journ., 24, 491 (1900).
6
Euler, Hofmeister’s Beitriige, 7, 1 (1906).
7
Trans. Chem. Soc, 57, 926, 1890; Journ. Amer. Chem. Soc, 30, 1160, 1564 (1908).
8
Skand. Arch. f. Physiol., 5, 358 (1895).
9
Hofmesietr’s Beitriige, 2, 169 (1902).
10 Journ. of Physiol., 30, 334 (1903).
11
Ibid., 32, 207 (1905).
12
Ibid., 32, 468 (1905); 34, 370 (1906).
13 Arrhenius, Immunochemie, Leipzig, 1907, 46.
14 Zeitschr. f. physiol. Chem., 57, 478 (1908).
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