What Is The Function Of Vitamin B6
Vitamin B 6 is a cofactor of numerous enzymes involved in amino acid metabolism, and it comes in the form of pridoxal phosphate. The different reactions of pyridoxal phosphate in amino acid metabolism are based on the same chemical principle, namely the capacity of trans-amino groups of substrates with carbonyl groups of coenzymes to stabilize amino acid carbanions and destabilize -carbon bonds. The catalytic groups of the specific enzyme to which the pyridoxal phosphate is coupled determine which bond will break. Transamination processes (which can also be catalyzed by pyridoxamine phosphate), decarboxylation, transulfhydration, desulfhydration, dehydration, deamination, racemization, and synthesis are some of the amino acid metabolic reactions pyridoxal phosphate is involved in.
Transaminases are the most common vitamin B 6-dependent enzymes, and the majority of them utilise -ketoglutarate as an amino group receiver. Transaminases, often known as aminotransferases, are enzymes that convert amino acids to keto acids. Amino groups are transferred from glutamate to pyruvate, resulting in -ketoglutarate and alanine, or from aspartate to -ketoglutarate, resulting in oxaloacetate and glutamate. Transaminases are therefore a crucial connection between amino acid, carbohydrate, and fatty acid metabolism and the citric acid cycle.
Decarboxylases are enzymes that convert amino acids into amines such as histamine, hydroxytyramine, serotonin, -aminobutyric acid, ethanolamine, and taurine, some of which have a lot of physiological activity (regulation of blood vessel diameter and bile acids). As a cofactor of the enzymes cystathionine synthase and cystathiase, which convert methionine to cysteine, pyridoxal phosphate is also involved in transulfhydration / desulfhydration processes, i.e. in the metabolism of methionine. This mechanism is critical for homocysteine metabolism, which is a risk factor for cardiovascular disease.
Lipid metabolism
Vitamin B 6 is a necessary component of the enzymes that produce sphingolipids. Pyridoxal phosphate-dependent transferase catalyzes the condensation reaction of serine with palmitoyl CoA to produce 3-dehydrosphinganin, a sphingolipid precursor. Sphingolipid degradation is also reliant on vitamin B 6 because S1P lyase, the enzyme that breaks down sphingosine-1-phosphate, requires pyridoxal-phosphate. Vitamin B 6 is also involved in the metabolism of polyunsaturated fatty acids, albeit the exact role is unknown. It is known, however, that a shortage in this vitamin causes decreased 6-desaturase activity and has a deleterious impact on the synthesis of eicosapentaenoic (icosapentaenoic) and docosahexaenoic acid.
Glucose metabolism
Glycogen is a glucose polymer that is used to store glucose in animal cells. When the body requires glucose, it is broken down through the process of glycogenolysis. The enzyme glycogen phosphorylase is involved in this process, and it uses pyridoxal phosphate to create glucose-1-phosphate. The glucose-1-phosphate produced is transformed to glucose-6-phosphate, which is used in the glycolysis or pentose phosphate pathways. All cells in our bodies have the potential to store glucose in the form of glycogen, but the liver and muscles store the majority of it.
Hemoglobin synthesis
Porphyrin is a common tetrapyrrole ring found in hem-containing proteins (cytochromes, hemoglobin, and myoglobin). Pyridoxal phosphate is a cofactor of the - Aminolevulinic Acid (ALA) enzyme, which catalyzes the condensation and decarboxylation processes that produce -aminolevulinic acid from succinyl-CoA and glycine in porphyrin biosynthesis. Porphobilinogen is formed from two molecules of -aminolevulinic acid, protoporphyrin IX is formed from four molecules of porphobilinogen, and heme is formed by adding iron to the tetrapyrrole ring. Pyridoxal phosphate and pyridoxal may also bind to hemoglobin, affecting oxygen intake and release.
Nucleic acid synthesis
Pyridoxal phosphate functions as a coenzyme in C1-unit transfer reactions, which are important in the production of nucleic acids. For example, pyridoxal phosphate is a coenzyme of serine hydroxymethyltransferase, which catalyzes the transfer of C1-units, -hydroxymethyl groups of serine, on tetrahydrofolate, and -carbon serine is one of the major sources of C1-units used in the biosynthesis of purines (adenine and guanine), major components of DNA (See "Vitamin B 9 ").
