The benefits of vitamin B12
Glutamyl and methylglutamine are two coenzyme forms of vitamin B12. The cobalt ion is connected to n-3 of 5,6-2 methylphenylimidazole above the plane of the cobalt ring and C5 ‘of 5’- deoxyadenosine below the plane. For vitamin B12 in general application, CN is connected to cobalt ion, called cyanocobalamine, which is a green crystal.
Physiological function editing and broadcasting
effect
vitamin B12 is known to be a coenzyme of several mutases, such as methyl aspartate mutase, which catalyzes the conversion of Glu to methyl ASP, and methyl malonyl COA mutase, which catalyzes the conversion of methyl malonyl COA to succinyl COA. vitamin B12 coenzyme also participates in the transfer reaction of methyl and other one carbon units.
B12 mainly exists in meat. Soybeans in plants and some herbal medicines also contain B12, which can be synthesized by intestinal bacteria, so it is generally not deficient. However,vitamin B12 is a vitamin that people with digestive tract diseases are prone to lack, and it is also an indispensable element for red blood cell production. If it is seriously deficient, it will lead to pernicious anemia!
Vitamin B12 is widely found in animal food. And its form cannot be absorbed by the human body. In addition, vitamin B12 is also the only vitamin containing essential minerals. It is also called red vitamin because it contains cobalt. It is a small number of colored vitamins. Although vitamin B12 belongs to group B vitamins, it can be stored in the liver. After the storage is exhausted, the symptoms of deficiency will appear after more than half a year. The human body needs very little vitamin B12. As long as the diet is normal, it will not be deficient. Special attention should be paid to a small number of people with malabsorption.
Absorption metabolism
Vitamin B12 in food combines with protein and enters the human digestive tract. Under the action of gastric acid, pepsin and trypsin, vitamin B12 is released and combines with a glycoprotein internal factor (if) secreted by gastric mucosal cells. Vitamin b12-if complex is absorbed in the ileum. Vitamin B12 is stored in small amounts, about 2~3mg in the liver. It is mainly discharged from urine and partly from bile.
physiological function
There are two main factors: ① as a cofactor of methyltransferase, it participates in the synthesis of methionine, thymine, etc. for example, it converts methyltetrahydrofolate into tetrahydrofolate and transfers the methyl to the methyl receptor (like type cysteine), so that the methyl receptor becomes a methyl derivative (like methionine, i.e. methylhomocysteine). The reaction is shown in the figure. Therefore, vitamin B12 can promote protein biosynthesis and affect the growth and development of infants in case of deficiency. ② Protect the transfer and storage of folic acid in cells. When vitamin B12 is deficient, the folate content in human erythrocytes is low, and the folate stored in the liver is reduced. This may be related to the lack of vitamin B12, which makes it difficult for methyl to transfer from homocysteine to methionine. Methyl accumulates in the cells, damaging the storage of tetrahydrofolate in the cells, because tetrahydrofolate has a strong tendency to combine with methyl to form methyltetrahydrofolate, which synthesizes polyglutamic acid.