Temperature is the most important factor influencing
enzyme activity.
Argumentative Discussion
This essay will be about factors influencing the enzyme
activity. I will also prove the statement weather temperature is the most
important factor influencing enzyme activity, or not. Lean back and just listen
or read on your own.
Enzymes are essential for almost all the chemical
reactions that take place inside living cells. However, the activities of the
enzymes can be enhanced or inhibited by a number of factors.
Enzymes are protein-based complex molecules produced
by the cells. There are several enzymes which are involved with different
biochemical reactions. Each of these enzymes present in our body can influence
any one particular chemical reaction or a set of reactions. They serve as
organic catalysts and enhance (verbessern, erhöhen) the speed of the reactions in which they take part. In the absence
of an enzyme, the speed of a chemical reaction becomes extremely slow. Some of
these reactions may not occur if the right kind of enzyme is not present in the
body.
An enzyme can increase the speed of a chemical
reaction in many ways. The chemical substances that are present at the start of
a biochemical process is termed as substrates which experience chemical changes
to form one or more end products. Basically, the active site of the enzymes
forms a temporary bond with the substrate. During this time, an enzyme lowers
the activation energy of the participant molecules which in turn speeds up the
reaction. After the reaction is over, the newly formed product leaves the
surface of the enzyme and the enzyme gets back its original shape. Thus, you
can say it participates in the reaction without undergoing any physical or
chemical change. Therefore, the same enzyme is used again and again for the
specific process.
Temperature, substrate concentration, and pH are three
of some other factors that can affect enzyme activity. Without enzymes, many
essential processes, such as digestion, would occur too slowly for life to
continue. Many enzymes have an optimal temperature and an optimal pH. But how does
that actually work?
First off all, all enzymes need a favorable
temperature to work properly. The rate of a biochemical reaction increases with
rise in temperature. This is because the heat enhances the kinetic energy of
the participant molecules which results in more number of collisions between
them. On the other hand, it is mostly found that in low temperature conditions,
the reaction becomes slow as there is less contact between the substrate and
the enzyme. However, extreme temperatures are not good for the enzymes. Under
the influence of very high temperature, the enzyme molecule tends to get distorted,
due to which the rate of reaction decreases. In other words, a denatured enzyme
fails to carry out its normal functions. In the human body, the optimum
temperature at which most enzymes become highly active lies in the range of 35
°C to 40 °C.
The efficiency of an enzyme is also largely influenced
by the pH value of its surroundings. This is because the charge of its
component amino acids changes with the change in the pH value. Each enzyme
becomes active at a certain pH level. In general, most enzymes remain stable
and work well in the pH range of 6 and 8. However, there are some specific
enzymes which work well only in acidic or basic surroundings. The favorable pH
value for a specific enzyme actually depends on the biological system in which
it is working. When the pH value becomes very high or too low, then the basic
structure of the enzyme undergoes changes. As a result, the active site of the
enzyme fails to bind well with the substrate properly and the activity of the
enzyme gets badly affected. The enzyme may even stop functioning completely.
Now: Substrate concentration plays a major role in
various enzyme activities. This is obviously because higher concentration of
substrate means more number of substrate molecules are involved with the enzyme
activity. Whereas, a low concentration of substrate means less number of
molecules will get attached to the enzymes. This in turn reduces the enzyme
activity. When the rate of an enzymatic reaction is maximum and the enzyme is
at its most active state, an increase in the concentration of substrate will
not make any difference in the enzyme activity. In this condition, the
substrate is continuously replaced by new ones at the active site of the enzyme
and there is no scope to add those extra molecules there.
In any enzymatic reaction, the quantity of substrate
molecules involved is more as compared to the number of enzymes. A rise in
enzyme concentration will enhance the enzymatic activity for the simple reason
that more enzymes are participating in the reaction. The rate of the reaction
is directly proportional to the quantity of enzymes available for it. However,
that does not mean that a constant rise in concentration of enzymes will lead
to a steady rise in the rate of reaction. Rather, a very high concentration of
enzymes where all the substrate molecules are already used up does not have any
impact on the reaction rate. To be precise, once the rate of reaction has achieved
stability, an increase in the quantity of enzymes does not affect the rate of reaction
anymore.
As their name suggest, inhibitors are those substances
that have a tendency to prevent activities of the enzymes. Enzyme inhibitors
interfere with the enzyme functions in two different ways. Based on this, they
are divided into two categories: competitive inhibitors and noncompetitive
inhibitors. A competitive inhibitor has a structure which is the same as that
of a substrate molecule, and so it gets attached to the activated center of the
enzyme easily and restricts the bond formation of enzyme-substrate complex. A
noncompetitive inhibitor is the one which brings about changes in the shape of
the enzymes by reacting with its active site. In this condition, the substrate
molecule cannot bind itself to the enzyme and thus, the following activities
are blocked.
From these conditions gained it can be observed that
as high as the concentration of the enzyme catalyse, or as high as the concentration
of the substrate hydrogen + oxygen, the higher the rate of reaction. This
direct relationship is due to the rule that as much concentrated two substances
there are, the more molecules there are of them in a given solution. Therefore
there will be a higher chance of collisions between molecules, resulting in
more enzyme-substrate complexes and therefore giving higher rate of reactions.
This of course leds to the conclusion, that the given
statement at the top is false. Temperature is one of the factors, but it is not
the most important factor influencing enzyme activity.