Enzyme: Properties, functions, classification

EnzymesA class of proteins that act as catalysts and increase the rates of biochemical reactions. They are not consumed during the reaction.
General properties of enzyme structureEnzymes are linear chains of amino acids that fold into a three-dimensional structure. The sequence of amino acids determines the catalytic activity. Enzymes have an active site consisting of a catalytic site and binding sites. The structure of the catalytic site is essential for activity.
Factors influencing enzyme activityConcentrations of reactants (substrates, coenzymes, cofactors), products, and enzyme; temperature; pH; presence of activators, inhibitors, and inactivators.
Effect of increasing substrate concentrationIncreasing substrate concentration increases the reaction rate until a certain point. After reaching saturation, further increase in substrate concentration does not affect the rate as the enzyme molecules become saturated.
Effect of increasing enzyme concentrationIncreasing enzyme concentration increases the reaction rate until a saturation point where the enzyme is no longer the limiting factor.
Influence of temperature on enzyme activityIncreasing temperature initially increases enzyme activity, but beyond a certain point, the enzyme becomes denatured, leading to a decline in activity.
Influence of pH on enzyme activitypH dependency varies among enzymes. There is an optimal pH at which the enzyme activity is highest, and deviations from this pH result in reduced activity.
Activators, inhibitors, and inactivatorsActivators are molecules that bind to enzymes and increase their activity. Inhibitors bind to enzymes and inhibit their activity. Inactivators irreversibly inhibit enzyme activity. These molecules are involved in the allosteric regulation of enzymes.
Classification of enzymesEnzymes are classified based on the type of reactions they catalyze. The main enzyme classes include oxido-reductases, transferases, hydrolases, lyases, isomerases, and ligases.
Examples of coenzymes with different enzyme classesExamples of coenzymes include NAD+, NADH + H+, NADP+, NADPH + H+, FAD, FADH2, Cu2+, Cu+, ATP, and biotin. These coenzymes are associated with specific enzyme classes.
Distribution of enzymesEnzymes are distributed within cells and tissues depending on the type of reactions required. For example, hydrolases are found in lysosomes, peroxidases in peroxisomes, and DNA polymerases in the nuclei.
Interconvertible forms of enzymesSome enzymes exist in different forms that can be interconverted through phosphorylation or dephosphorylation. Examples include glycogen phosphorylase, glycogen synthase, and others.
IsozymesMultiple forms of enzymes with genetically determined differences in polypeptide amino acid sequences. They have identical functions but different structures. An example is lactate dehydrogenase (LDH).
Properties of lactate dehydrogenase (LDH)LDH is composed of four subunits (tetramer) and catalyzes the conversion of lactate to pyruvic acid and back. It has five isozymes (LDH-1 to LDH-5) with different tissue distributions.
Isoenzymes of LDH and their locationsLDH-1 (H4) – heart and RBC; LDH-2 (H3M) – reticuloendothelial system; LDH-3 (H2M2) – brain and kidneys; LDH-4 (HM3) – kidneys, placenta, and pancreas; LDH-5 (M4) – liver and skeletal muscle.
Use of LDH as a cardiac markerLDH-1 isozyme is normally found in the heart muscle. A high LDH-1 level to LDH-2 suggests a myocardial infarction. LDH levels are also high in tissue breakdown or hemolysis.
CoenzymeA nonprotein compound necessary for the functioning of an enzyme, acting as a helper molecule. Example: Nicotinamide adenine dinucleotide (NAD) in lactate dehydrogenase.
ApoenzymeThe protein component of an enzyme without a coenzyme, considered an incomplete enzyme.
CofactorAn inorganic substance that regulates and controls enzymatic activities. Examples include Mg2+ required by hexokinase in phosphoryl group transfer.
HoloenzymeThe complete form of an enzyme with the required cofactor. Examples include DNA polymerase composed of several protein subunits.
Properties of enzymesCatalytic activity, specificity, reversibility, sensitivity to heat and temperature, sensitivity to pH, degradation, signal transduction, energy generation, ion pump action, clearance of foreign substances.
Types of enzyme specificityBond specificity, group specificity, substrate specificity, optical specificity, co-factor specificity, geometric specificity.
Active siteThe part of an enzyme where the substrate binds for the reaction to occur. It is a specific region of the protein formed by folding. Substrates must combine with the active site for the reaction to proceed.
Types of enzyme inhibitionCompetitive inhibition, non-competitive inhibition, uncompetitive inhibition, suicide inhibition. Different types of inhibitors bind to the enzyme and affect its activity.

Get help to do your homework

We have top writers to get your essays done professionally. Place your order today to receive an original paper via email.

Write my Paper

Cite this article in APA

If you want to cite this source, you can copy and paste the citation below.

Editorial Team. (2023, May 24). Enzyme: Properties, functions, classification. Help Write An Essay. Retrieved from https://www.helpwriteanessay.com/blog/enzyme-properties-functions-classification/

Pay Someone to Write My Research Paper

You can pay someone to do your research paper on coursepivot today. This is the number one essay writing service for original and top-notch papers.

Write My Paper