Final answer:
Enzymes are protein catalysts that increase the rates of reactions in living organisms. They are affected by factors such as temperature, pH, substrate concentration, and enzyme concentration. Enzymes have specific substrate specificity and catalyze reactions by bringing substrates together, altering bond structures, providing optimal conditions, or participating directly in the reaction.
Step-by-step explanation:
The single most important property of enzymes is the ability to increase the rates of reactions occurring in living organisms, a property known as catalytic activity. Because most enzymes are proteins, their activity is affected by factors that disrupt protein structure, as well as by factors that affect catalysts in general. Factors that disrupt protein structure include temperature and pH; factors that affect catalysts in general include reactant or substrate concentration and catalyst or enzyme concentration. The activity of an enzyme can be measured by monitoring either the rate at which a substrate disappears or the rate at which a product forms.
To recapitulate, the two most important kinetic properties of an enzyme are:
- how quickly the enzyme becomes saturated with a particular substrate, which is related to the Km for the reaction, and
- the maximum rate of the catalyzed reaction, described by the Vmax for the reaction.
Enzymes are chemical catalysts that accelerate chemical reactions at physiological temperatures by lowering their activation energy. Enzymes are usually proteins consisting of one or more polypeptide chains. Enzymes have an active site that provides a unique chemical environment, comprised of certain amino acid R groups (residues). This unique environment is perfectly suited to convert particular chemical reactants for that enzyme, scientists call substrates, into unstable intermediates that they call transition states. Enzymes and substrates bind with an induced fit, which means that enzymes undergo slight conformational adjustments upon substrate contact, leading to full, optimal binding. Enzymes bind to substrates and catalyze reactions in four different ways: bringing substrates together in an optimal orientation, compromising the bond structures of substrates so that bonds can break down more easily, providing optimal environmental conditions for a reaction to occur, or participating directly in their chemical reaction by forming transient covalent bonds with the substrates.
The rate at which chemical reactions occur is influenced by several properties of the reactants: temperature, concentration and pressure, and the presence or absence of a catalyst. An enzyme is a catalytic protein that speeds up chemical reactions in the human body.
An enzyme is an organic catalyst produced by a living cell. Enzymes are such powerful catalysts that the reactions they promote occur rapidly at body temperature.
The molecule or molecules on which an enzyme acts are called its substrates.
An enzyme has an active site where its substrate or substrates bind to form an enzyme-substrate complex.
The original lock and key model of enzyme and substrate binding pictured a rigid enzyme of unchanging configuration binding
to the appropriate substrate. The newer induced fit model describes the enzyme active site as changing its conformation after binding to the substrate.
Three conditions are necessary for a chemical reaction to happen:
substrate specificity
: These enzymes are specific for the substrate upon which they act. This is further classified as follows.
a) Absolute specificity: These enzymes are highly specific and act on one particular substrate only and no other substrate. Ex. Urease, catalase, aspartase.
b) Relative specificity: These enzymes act on one particular bond. Ex. D-amino acid oxidase.
c) Group specificity: These enzymes act on only one particular group.
As you view Enzymes, focus on these concepts:
- the role of enzymes in nature,
- other uses of enzymes.