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56 GENERAL AND PHYSICO-CHEMICAL.
velocity for every moment is proportional to the concentration of the
body decomposed, which is shown by the velocity coefficient in the same
experiment being constant at different times.
2. The velocity coefficient or the reaction velocity with constant
concentration of substrate is proportional to the quantity of catalyst.
The first law has been shown for certain enzymes in case an excess
of enzyme is present, namely for saccharase, 1
lactase 2
and trypsin.3
It
was found that the decomposition in a certain time was proportional to
the substrate. In other cases the determination of the correctness of
the law was accomplished with difficulty. A part of the enzyme may
during an experiment be either destroyed or in other ways (combining
with the product) be put out of action; then reverse reactions may take
place (page 11) and finally in many cases our analytical methods are
incapable of obtaining comparative results for different decompositions,
as the reaction in many cases takes place step by step, or several reac-
tions occur at the same time.4
Only in a few cases with especially
simple reactions have constant values been found for the velocity
coefficient at the beginning, as long as the quantity of reaction product
was small and the active quantity of enzyme remained unchanged
according to the formula (see page ll).5
t
X
i
C
k= — log
t
b
C-x
Recently Hudson 6 has found constant values for k for the entire
process of inversion of cane-sugar by saccharase in a faintly acid reac-
tion. The reason for the different results of earlier investigators 7
is
due, in part, according to Hudson, to the fact that the multirotation
of the glucose formed was not considered by these experimenters before
the extent of inversion was determined polariscopically. In the cleavage
of salicin by emulsin Hudson and Paine 8 obtained constant values
for k in the entire process.
1
Brown, Proc. Chem. Soc, 18, 14 (1902).
2
Armstrong, Proc. Roy. Soc, 73, 500 (1904).
* Hedin, Journ. of Physiol., 32, 475 (1905).
* Hedin, Zeitschr. f. physiol. Chem., 57, 468 (1908).
6
Senter, Zeitschr. f. physik. Chem., 44, 257 (1903); Issajew, ibid., 42, 102; 44,
546; Eider, Ilofrneister’s Beitrage, 7, 1 (1906); Dietz, Zeitschr. f. physiol. Chem.,
52, 301 (1907); Taylor, Journ. of biol. Chem., 2, 93 (1906); Nicloux, Compt. rend,
soc. biol., 56, 840 (1904); Rona, Bioch. Zeitschr., 33, 413 (1911); 39, 21 (1912); Euler,
Zeitschr. f. physiol. Chem., 51, 213 (1907).
6
Journ. Amer. Chem. Soc, 30, 1160, 1564 (1908).
7
Bee Henri, Zeitschr. f. physik. Chem., 39, 194 (1901) also A. J. Brown, Trans.
Chem. Soc, 81, 373 (1902).
8
Journ. Amer. Chem. Soc, 31, 1242 (1909).
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