Received Oct 15; Accepted Nov This article has been cited by other articles in PMC.
Pernicious anemia is a megaloblastic anemia resulting from vitamin B12 deficiency that develops as a result of a lack of intrinsic factor being released from stomach parietal cells leading to subsequent malabsorption of the vitamin. The major cause of the loss of intrinsic factor is an autoimmune destruction of the parietal cells that secrete it.
Surgical removal of a part of the stomach can also result in loss of intrinsic factor resulting in pernicious anemia. In rare cases individuals inherit mutation in the GIF gene that encodes intrinsic factor resulting in pernicious anemia.
The pernicious anemias result from impaired DNA synthesis due to a block in purine and thymidine biosynthesis.
Introduction to Vitamins and Minerals. Vitamins are organic molecules that function in a wide variety of capacities within the body. The most prominent function of the vitamins is to serve as cofactors (co-enzymes) for enzymatic reactions. Terpenoid- and Shikimate-Derived Natural Product Total Synthesis: A Personal Analysis and Commentary on the Importance of the Papers That Appear in this Virtual Issue. A natural product is a chemical organic substance which is produced by the living organisms found in the nature that are produced by the pathways of primary and secondary metabolism [1,2].It can be synthesized by the chemical synthesis by semi synthesis and total synthesis and responsible for the development in the field of .
The block in nucleotide biosynthesis is a consequence of the effect of vitamin B12 on folate metabolism. When vitamin B12 is deficient essentially all of the folate becomes trapped as the N5-methylTHF 5-methylTHF; or simply methylTHF derivative as a result of the loss of functional methionine synthase also called homocysteine methyltransferase.
This trapping prevents the synthesis of other THF derivatives required for the purine and thymidine nucleotide biosynthesis pathways. Neurological complications also are associated with vitamin B12 deficiency and result from a progressive demyelination of nerve cells.
The demyelination is thought to result from the increase in methylmalonyl-CoA that results from vitamin B12 deficiency that is associated with loss of methylmalonyl-CoA mutase activity. The loss of methylmalonyl-CoA mutase activity with deficiencies in B12 results in an accompanying methylmalonic acidemia.
Methylmalonyl-CoA is a competitive inhibitor of malonyl-CoA in fatty acid biosynthesis as well as being able to substitute for malonyl-CoA in any fatty acid biosynthesis that may occur. Since the myelin sheath that protects nerve cells is in continual flux the methylmalonyl-CoA-induced inhibition of fatty acid synthesis results in the eventual destruction of the sheath.
The incorporation methylmalonyl-CoA into fatty acid biosynthesis results in branched-chain fatty acids being produced that may severely alter the architecture of the normal membrane structure of nerve cells.
Contributing to the neural degeneration seen in vitamin B12 deficiency is the reduced synthesis of S-adenosylmethione SAM; also abbreviated AdoMet due to loss of the methionine synthase catalyzed reaction.
The conversion of phosphatidylethanolamine PE to phosphatidylcholine PC requires the enzyme phosphatidylethanolamine N-methyltransferase encoded by the PEMT gene which carries out three successive SAM-dependent methylation reactions.
This reaction is a critically important reaction of membrane lipid homeostasis. Therefore, the reduced capacity to carry out the methionine synthase reaction, due to nutritional or disease mediated deficiency of vitamin B12results in reduced SAM production and as a consequence contributes to the neural degeneration i.
Deficiencies in B12 can also lead to elevations in the level of circulating homocysteine and elevated excretion of the oxidized dimer of homocysteine called homocystine.
Elevated levels of homocysteine are known to lead to cardiovascular dysfunction. Due to its high reactivity to proteins, homocysteine is almost always bound to proteins, thus thiolating them leading to their degradation.
Homocysteine also binds to albumin and hemoglobin in the blood.
Some of the detrimental effects of homocysteine are due to its' binding to lysyl oxidase, an enzyme responsible for proper maturation of the extracellular matrix proteins collagen and elastin.
Production of defective collagen and elastin has a negative impact on arteries, bone, and skin and the effects on arteries are believed to be the underlying cause for cardiac dysfunction associated with elevated serum homocysteine.
The increased risk for thrombotic episodes, such as deep vein thrombosis DVTassociated with homocysteinemia is due to homocysteine serving as a contact activation nucleus for activation of the intrinsic coagulation cascade.
Folic acid is sometimes referred to as vitamin B9. The terms folic acid and folate are sometimes used interchangeably but from a dietary perspective they are distinctly different. The term folate should be used to refer only to the bioactive forms of folic acid, namely dihydrofolate DHF and tetrahydrofolate THF and their derivatives.NATURAL PRODUCTS.
OSYNTHES or an organic chemist, a natural product is one that is produced by a living organism. This definition encompasses many compounds already discussed, the synthesis machinery of the cellular enzymes. Regardless of their utility.
ABSTRACT. Nanocomposites, a high performance material exhibit unusual property combinations and unique design possibilities. With an estimated annual growth rate of about 25% and fastest demand to be in engineering plastics and elastomers, their potential is so striking that they are useful in several areas ranging from packaging to biomedical applications.
A natural product is a chemical organic substance which is produced by the living organisms found in the nature that are produced by the pathways of primary and secondary metabolism [1,2].It can be synthesized by the chemical synthesis by semi synthesis and total synthesis and responsible for the development in the field of .
The Future of Total Synthesis a brief forward The idea for tonights topic was from discussions with all of you over the past years Camphor was a scarce natural product with a worldwide demand camphor Important milestone in synthetic organic chemistry MeMe O Me.
Total Synthesis of Natural Products. Introduction. Translation is the RNA directed synthesis of polypeptides.
This process requires all three classes of RNA. Although the chemistry of peptide bond formation is relatively simple, the processes leading to the ability to form a peptide bond are exceedingly complex. The Importance of Natural Products Synthesis This prologue is primarily for the benefit of readers outside of the field of chemistry, who A natural product synthesis involves looking at a structure that has been isolated from nature, and then finding a .