Amylase
The enzyme amylase will catalyze the hydrolysis of starch to maltose when
the pH
is near 7.0. But when the HCl is added to the solution the amylase
will be
denatured which results in the enzyme being deactivated. The iodine
serves as an
indicator for the presence of starch. Iodine (I2) will reach
with iodide ion to
produce the I3- ion. This ion will form a dark blue
complex with the starch
molecule. Like most chemical reactions, the rate of
an enzyme-catalyzed reaction
increases as the temperature is raised. A ten
degree Centigrade rise in
temperature will increase the activity of most
enzymes by 50 to 100%. Variations
in reaction temperature as small as 1 or 2
degrees may introduce changes of 10
to 20% in the results. In the case of
enzymatic reactions, this is complicated
by the fact that many enzymes are
adversely affected by high temperatures. As
shown in Figure 13, the reaction
rate increases with temperature to a maximum
level, then abruptly declines
with further increase of temperature. Because most
animal enzymes rapidly
become denatured at temperatures above 40·?C,
most enzyme determinations are
carried out somewhat below that temperature. Over
a period of time, enzymes
will be deactivated at even moderate temperatures.
Storage of enzymes at
5·?C or below is generally the most suitable. Some
enzymes lose their
activity when frozen. . As amylase breaks down starch, less
and less starch
will be present and the color of the solution (if iodine is
added) will
become lighter and lighter. Enzymes are biological molecules that
catalyze
many different chemical reactions. With few exceptions, all enzymes
are
proteins and each enzyme is specific to a certain chemical reaction.
Enzymes
must maintain a specific three dimensional structure in order to
function
properly. If an enzyme's structure is altered (by heat or harsh
chemicals) it
may not function at all. This breakdown (denaturation) of an
enzyme's.