Coenzymes and their functions

Coenzymes, vitamin derived coenzymes and their functions.

1. COENZYMES (TPP, CoA, FMN) BY- SARAH HAMID M.Sc BIOTECHNOLOGY PGY-1

2. IMPORTANT TERMS Catalyze- To cause or accelerate a reaction. Enzyme- A protein that catalyzes chemical reactions within an organism. Active site- The region on an enzyme where the substrate bind during a reaction. Substrate- The substance on which an enzyme acts to make a new product. Cofactors-  Inorganic species or at least nonprotein compounds that aid enzyme function by increasing the rate of catalysis. Typically, cofactors are metal ions. Cosubstrates -  These a re coenzymes that bind tightly to a protein, yet will be released and bind again at some point. Prosthetic groups-  These are enzyme partner molecules that bind tightly or covalently to the enzyme (coenzymes bind loosely).   Prosthetic groups help proteins bind other molecules, act as structural elements, and act as charge carriers.

3. Apoenzyme - It is the name given to an inactive enzyme that lacks its coenzymes or cofactors. Holoenzyme- It  is the term used to describe an enzyme that is complete with its coenzymes and cofactors. Holoprotein- It  is the word used for a protein with a prosthetic group or cofactor.

4. INTRODUCTION A coenzyme is defined as an organic molecule that binds to the active sites of certain enzymes to assist in the catalysis of a reaction. It can be considered a helper molecule for a biochemical reaction. They are intermediate carriers of an atom or group of atoms, allowing a reaction to occur.  Coenzymes are not considered part of an enzyme's structure. They are sometimes referred to as  cosubstrates . Some enzymes require several coenzymes and cofactors.

5. FEATURES OF A COENZYME Its an organic molecule I t is a small, non proteinaceous molecule that provide a transfer site for a functioning enzyme.  Coenzymes cannot function on their own and require the presence of an enzyme. Coenzymes, which are often vitamins or derivatives of vitamins, therefore play a crucial role in the regulation of most enzyme activities Like enzymes, it can be reused and recycled. ENZYME COENZYME

6. HOW COENZYMES WORK ?

7. WHAT ARE THE FUNCTIONS OF COENZYMES ?? An enzyme without a coenzyme is called an apoenzyme. Without coenzymes or cofactors, enzymes cannot catalyze reactions effectively. In fact, the enzyme may not function at all. If the reactions cannot occur at the normal catalyzed rate, then an organism will have difficulty sustaining life. When an enzyme gains a coenzyme, it then becomes a holoenzyme, or active enzyme. These active enzymes change substrates into the products, an organism needs to carry out essential functions. They attach to a portion of the active site on an enzyme, which enables the catalyzed reaction to occur.

8. EXAMPLES OF COENZYMES During the conversion of pyruvate to acetyl coenzyme A (CoA), several coenzymes including free CoA, thiamine pyrophosphate (TPP), lipoic acid (LA), flavin adenine dinucleotide (FAD), two cellular redox enzymes including oxidized nicotinamide adenine dinucleotide (NAD) and reduced nicotinamide adenine dinucleotide (NADH) are required. The B vitamins serve as coenzymes essential for enzymes to form fats, carbohydrates, and proteins. Adenosine triphosphate(ATP) is an example of an essential non-vitamin coenzyme. It is the most widely distributed coenzyme in the human body. It transports substances and supplies energy needed for necessary chemical reactions and muscle contraction.

9. TPP(THIAMINE PYROPHOSPHATE) Thiamine pyrophosphate (TPP), the active form of  thiamine , functions as a  coenzyme  for a number of enzymes involved in  carbohydrate metabolism , thus making metabolites from this metabolism and keto analogues from amino and  fatt y acid metabolism  available for the production of energy. TPP can be found in various sources; yeast, wheat, and  sunflower seeds  are considered good sources of the vitamin, whereas dairy products contain only small amounts. I ncreased losses and impaired biosynthesis of TPP and can lead to various forms of beriberi, a disease appearing mostly in Southeast Asia. 

10. FUNCTIONS OF TPP Enzymes carrying out decarboxylation and transketolation reactions, such as the pyruvate dehydrogenase complex (PDH complex) and transketolase rely on TPP as a catalytic cofactor. TPP acts catalytically in the decarboxylation of α-keto acids and the transketolase reaction. In the mechanism of TPP-dependent enzymes, the cofactor is a carrier of hydroxyalkyl residues (also referred to as "active aldehydes")

11. COENZYME A(CoA) Coenzyme A, a helper molecule, is a nonprotein chemical substance needed for the activation of some enzymes, the proteins that catalyze or activate important chemical reactions within the body. Its notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle.   It is naturally synthesized from pantothenic acid or vitamin B5 Sources of vitamin B5 meat, vegetables, legumes and milk. Coenzyme A and its derivatives can also be successfully produced in chemical laboratories. STRUCTURE OF COENZYME A

12. FUNCTIONS OF CoA Fatty Acid Synthesis C oenzyme A is the helper molecule that facilitates the oxidation pathway. Its an important chemical substance used for the initiation of fatty acid production within the living cell. Without this much-needed process, there is no production of fatty acids, the compounds that maintain the integrity of the cell membrane, the protective covering of each living cell. 2. Drug and Enzyme Functioning Coenzyme A improves the functioning of some proteins, sugars and drugs,   In drugs, it is used to extend a medication's half-life. In cells, coenzyme A causes activation or inactivation of certain chemical compounds, such as enzymes. 3. Energy Production Coenzyme A, in the form of acetyl-coenzyme A, initiates the Krebs cycle, a chemical process within the body that results in the production of carbon dioxide and adenosine triphosphate ATP is an important, energy-rich compound that provides fuel and energy needed for the synthesis of protein and deoxyribonucleic acid.

13. FLAVIN MONONUCLEOTIDE(FMN) Flavin mononucleotide is a mononucleotide also referred to as riboflavin-5′-phosphate, riboflavin mononucleotide, or vitamin B2 phosphate. C hemical formula: C 17 H 21 N 4 O 9 P It is a biomolecule derived from vitamin B2 (riboflavin) through the catalytic activity of the enzyme riboflavin kinase. This means a phosphorylated vitamin B2 is FMN. Word flavin is derived from the Latin term flavus, for “yellow”. That is because riboflavin comes from ribose and flavin, which is the ring-moiety that imparts the yellow color to the oxidized molecule.  STRUCTURE OF FMN

14. FMN is capable of acting as an oxidizing agent. Compared with a common oxidizing agent NAD (nicotinamide adenine dinucleotide), FMN is a stronger oxidizing agent.  FMN can be found in tissues (e.g.  muscles ) and  cell s (e.g.  erythrocytes and  platelets ).  The mononucleotide FMN may be converted to FAD (a dinucleotide) trough the action of FAD pyrophosphorylase with ATP . FMN liberates free riboflavin, upon digestion.

15. FUNCTIONS OF FMN It assists certain oxidoreductases (e.g. NADH dehydrogenase) in various oxidation-reduction reactions.  It is also functions as a cofactor in blue-light photo receptors. This biomolecule is associated with the following biochemical pathways - vitamin B6 metabolism, riboflavin metabolism, pyrimidine metabolism, beta-alanine metabolism, arginine and proline metabolism, and pantothenate and C oA biosynthesis . FMN forms certain flavoproteins when conjugated with certain proteins. These proteins are essential in many biological processes, such as DNA repair, bioluminescence, photosynthesis, and the removal of free radicals. FMN is used in food industry as food additive e.g. in milk product, sweets and sugar products. It imparts an orange-red food color.

16. REFERENCES https://www.sciencedirect.com/ https://www.thoughtco.com/ https://www.biologyonline.com/ https://www.youtube.com/