Ben DeRosso
Biology Lab 1015
6/21/12
ENZYMES
PROCESS OF ENZYMES
The food we eat enters our stomachs through the digestive tract. In this tract, the food
encounters enzymes that break down food into nutrient molecules. An enzyme is typically a protein that
functions as an organic catalyst to speed up a chemical reaction, without affecting itself by the reaction.
Like in the digestive tract, cells contain many different types of enzymes, all causing reactions to occur
despite their location in the body. However, enzymes only allow reactions to speed up that would have
occurred anyway, not energetically unfavorable reactions. When an enzyme is present, the energy of
activation is lower than it would be without the enzyme.
REACTANTS
This is allowed to happen by enzymes bring reactants together in an effective way at body
temperature. This is also why cells require many different enzymes. Each enzyme is designed specifically
for the reaction it speeds. Reactions in an enzymatic reaction are called the enzymes substrates. These
substrates are specific to a particular enzyme, because of binding purposes, forming an enzymesubstrate complex. There is only one small part of the enzyme, called the active site, which binds with a
substrate(s) to form an enzyme substrate complex. The area of the active site undergoes a slight change
in shape to compensate for the substrate. This is called the induced fit model, because the enzyme is
induced to undergo change for an optimum fit. This change in shape will actually facilitate the reaction
that will now occur. After the reaction has been completed, the product is then released. The active site
then returns to its normal state, ready to bind itself with another substrate molecule. Since a cell needs
only a small amount the enzyme to start the reaction, cells are able to use the enzymes over and over
again.
REACTIONS, ROLES, AND SUBSTRATE CONCENTRATION
Certain enzymes actually participate in the reaction itself. The enzyme trypsin, digests protein by
breaking the peptide bonds. This active site contains three amino acids with r groups that will first
interact with the members of the peptide bond. First the bond will break, and then introduce the
components of water. The rate of reaction; is the amount of product produced per unit time. Enzymes
generally have a fast pace of work, but sometimes they can increase the rate of reaction by more than
10 million times. For a maximum rate, each substrate should be able to fill every active site on the
enzyme molecule. With an increased amount of substrate, and a proper temperature and ph, enzymatic
reactions will increase. When substrate concentration increases, generally enzyme activity increases as
well. This is because there is a larger chance of encounter between substrate molecules and the
enzyme. As more substrates fill active sites, more product results per unit time. When the active sites
are continuously filled, the rate of activity cannot increase anymore, and the maximum rate has been
reached. Certain things like temperature and pH will play a role in the rate of reaction. In most cases, as
the temperature increases, enzyme activity also increases. This happens because, in warmer
temperatures, encounters between enzyme and substrate are more effective. This is what determines
of whether an animal is active or inactive. The generally warm temperature of a mammal’s body allows
its enzymes to work at a constant rapid rate, despite a cold external temperature. Every enzyme also has
an optimal pH at which the rate of reaction is the most efficient. At this pH value, enzymes will have
their normal configurations. The structure of an enzyme depends on its reactions such as hydrogen
bonding, between R groups. Changes in pH can alter the ionization of these side chains and disrupt
normal interactions; with extreme pH conditions, denaturation will eventually occur. Many enzymes also
require the presence of an inorganic ion, or a nonprotien organic molecule, in order to be active; these
are called cofactors; in example inorganic ions such as copper, zinc, or iron. Non-protein organic
molecules are called coenzymes, and will assist the enzyme and may even contribute to reactions.