Introduction
The human body is composed of various cell types, tissues, and other specialised organs. The biological processes of breathing, digestion, excretion, and a few other metabolic activities are accelerated by chemicals that our body produces for effective functioning to maintain a healthy life. Enzymes are therefore essential to all living things to control all biological activities.
Many enzymes are basic proteins composed primarily of one or more amino acid sequences. The proper operation of other enzymes depends on a cofactor, a non-protein substance they consist of. Cofactors come in two varieties: organic molecules called coenzymes and inorganic ions like zinc or copper ions. Most coenzymes are either derived from vitamins or are themselves vitamins.
Several cofactors are required by certain enzymes or enzyme complexes. For instance, the multienzyme complex pyruvate dehydrogenase at the convergence of glycolysis and the citric acid cycle involves one metal ion and five organic cofactors. These include a metal ion (Mg2+), covalently bound lipoamide and flavin adenine dinucleotide (FAD), loosely attached thiamine pyrophosphate (TPP), and cosubstrates nicotinamide adenine dinucleotide (NAD+) and coenzyme A (CoA).
Table of Contents
- Definition and Examples of Enzyme Cofactor
- Types of Enzyme Cofactors
- Functions of Enzyme Cofactors
- Coenzyme Definition and Examples
- Frequently Asked Questions (FAQs)
Definition and Examples of Enzyme Cofactor
A cofactor is a non-protein molecule that supports a biochemical reaction. Cofactors can take the form of metal ions, organic substances or other molecules with beneficial characteristics not typically present in amino acids. While some cofactors, like ATP, can be produced by the body, others must be obtained through food.
Cofactors play an important role in understanding how biological activities occur at the biochemical level. How rapidly a reaction moves from its reactant to its product may depend on whether cofactors are present or absent.
Understanding cofactors is essential for studying health at the biological level. Humans and animals may suffer life-threatening illnesses or eventually die without the necessary cofactors.
Minerals come from the environment and cannot be produced by any living being. Our bodies cannot produce the organic molecules “vitamins,” so we must consume foods containing vitamins for our cells to execute essential life functions.
Examples of Cofactors
Folic Acid or Vitamin B9
Vitamin B9 or folic acid is frequently added to meals to promote general health. Amino acids, DNA and RNA must be produced by the body for cells to grow and divide.
Folic acid is important for expectant mothers, whose foetuses are rapidly generating new cells and organs. Folic acid deficiency can result in birth abnormalities in children or anaemia in expectant mothers who may not be able to produce sufficient new blood cells to sustain both themselves and the child.
Thiamine or Vitamin B1
Vitamin B1 is mostly present in edible seeds including beans, corn and rice. Thiamine is commonly added artificially to foods containing wheat, such as morning cereals, to enhance public health.
Thiamine helps the body produce various coenzymes that support important functions. Thiamine is converted into thiamine pyrophosphate, required to metabolise carbohydrates and amino acids.
Korsakoff Syndrome, a rare neurological condition found in patients with severe alcohol addiction, can have several causes, including acute thiamine deficiency.
Iron-Sulphur Clusters
Iron-sulphur clusters are groups of iron and sulphur ions that can arrange themselves into stable configurations. In contrast to amino acids and other chemical molecules, these clusters exhibit various unique characteristics.
Due to their specific features, iron-sulphur clusters are useful for biological processes involving electron transfers. This makes iron-sulphur clusters an essential component of enzymes and cofactors in energy transfer and electron transfer, such as Complex I and Complex II in the mitochondria, coenzyme Q, cytochrome C, and NADH dehydrogenase.
Types of Enzyme Cofactors
Vitamins
Vitamins are organic substances that act as cofactors in essential metabolic processes. Since the body cannot produce vitamins, they must usually be obtained through diet.
Numerous vitamins serve as cofactors to enable enzymes to catalyse processes, including the production of essential proteins. For example, vitamin C functions as a cofactor in the synthesis of collagen, a protein found in connective tissue.
Vitamin deficiency is a good example of a cofactor deficiency. Similar to how there are conceivable vitamin deficiencies with various symptoms, there are various cofactors that our body needs to carry out its different essential biochemical reactions.
Minerals
Like vitamins, minerals are substances that must be consumed for our cells to function effectively. The difference is that minerals are inorganic compounds that naturally occur and are commonly found in rocks and soil, whereas vitamins are organic molecules, containing carbon, generally produced by other living things.
Minerals essential for human wellness include copper, necessary for the function of certain liver enzymes that break down toxins. Iron is essential for the function of essential metabolic enzymes. The mineral magnesium is required for the function of DNA polymerase and many other enzymes. And zinc is also essential for DNA polymerase and some liver enzymes.
Organic Non-Vitamin Cofactors
Several cofactors are organic components that are not considered enzymes. Some of these might be produced by our bodies and are not considered vitamins.
ATP is an organic, non-vitamin cofactor that provides energy to various enzymes, transportation of proteins, and other metabolic activities. Coenzyme Q is an essential component of the mitochondrial transport chain. To transport oxygen throughout the body, our blood cells need heme which is a complex iron-containing molecule.
Functions of Enzyme Cofactors
Cofactors usually have the function of contributing chemical groups or qualities that are absent from other chemical groups.
For example, the cofactor ATP can transfer energy, which it uses to conduct chemical reactions like enzyme activities and protein transportation.
On the other hand, heme is an iron-containing chemical complex which connects with oxygen molecules. Our blood cells need heme to transport oxygen throughout our bodies.
As a result, cofactors may have a wide range of functions depending on their chemical components and characteristics.
Coenzyme Definition and Examples
A coenzyme is a chemical that works with the enzyme to start or support the enzyme’s activity. It can be considered as a supporting molecule in a biochemical process. Coenzymes are tiny, non-proteinaceous substances that serve as a transfer site for an active enzyme. They operate as intermediary carriers for an atom or group of atoms, enabling a reaction to take place.
Coenzymes are not recognized as a component of the structure of an enzyme. They are referred to as cosubstrates. Coenzymes need an enzyme to function; they are unable to do it on their own. Some enzymes require many cofactors and coenzymes.
Examples of Coenzymes
The B vitamins act as coenzymes, which are necessary for enzymes to produce carbohydrates, proteins, and lipids.
S-adenosyl methionine is an example of a non-vitamin coenzyme that carries a methyl group in bacteria, eukaryotes and archaea.
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