Page 5 - ALLEN'S COMMERCIAL ORGANIC ANALYSIS A TREATISE ON THE PROPERTIES, MODES OF ASSAYING... VOL VIII

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ENZYMES .

• BYE. FRANKLAND ARMSTRONG, PH.D.,D.Sc., F.C.G.I.

• The detection and relative estimation of enzymes is in most cases
a matter requiring some experience, particularly in such complicated
materials as plant and animal tissues. As a rule, it suffices to demon-
strate the action of the enzyme on the particular substance to which
it is related, but a control experiment should be made at the same time
with the boiled enzyme material. Any change in this is deducted
from that observed in the first case.
Enzymes enclosed in tissues with a living cell wall cannot as a rule
• be extracted until the protoplasmic structure is destroyed. This may
be effected in a number of ways:
(1) By drying the material quickly at a low temperature, 2o-30°,
and if necessary subsequently warming the partially dried material
to 5o or more.
(a) By autolysis of the material, usually with the addition of an
antiseptic to prevent bacterial action.
() By rapid dehydration brought about by stirring with absolute
alcohol or acetone.
(4) By the mechanical disintegration of the living tissue. This is
effected in a Buchner press or by rotating the cells very rapidly with
sand. _Soft organisms like bacteria can be hardened by freezing with
liquid air and then ground.
In general, aqueous or glycerol extracts of the materials, prepared
in some such manner as described, are used as sources of enzymes.
In special cases the solid material is used directly. The extracts
may be purified from crystalloids by dialysis. The dissolved enzyme
can be precipitated with alcohol or acetone, washed with alcohol and
ether and dried in a vacuum, and is thus obtained as a soft colourless
powder. The process generally entails a loss of activity.
The better studied enzymes are:
Sucroclasts... . .. Invertase, lactase, maltase
Amyloclasts...... Diastase
Glucosidoclasts...Emulsin, myrosin'
See vol. , art. Glcosides,