Biochem-SAM/B12/Folate-WVSOM Class of 2012
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| what is the basic function of folate and SAM? | transfer of one methyl group to another molecule
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| folate has what molecule on the end? | glutamate
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| can folate be synthesized? | no
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| what enzyme is responsible for reducing and activating folate? | dihydrofolate reductase (dhfr)
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| general process for making folate? | ingest->make monoglutamate->FH2->FH4
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| what molecule most often donates the carbon group to folate? | serine
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| what are the 3 main molecules that rely on folate for their synthesis? | purine and dtmp; serine; methylcobalamin
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| another name for B12? | methylcobalamin
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| what is the most common form of FH4-C? what is its function? | N5-methyl-FH4; transfers methyl group to B12
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| what is the other name for B12? why? what is important about cobalt? | cobalamin; because it has cobalt ring; can form carbon bonds
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| B12 can only be synthesized how? | bacteria
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| what are the 2 metabolites of B12? | methyl cobalamin or deoxyadenosylcobalamin
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| what are the 3 names for the proteins that bind B12 after ingestion? | Haptocorrin, Transcobalamin I, or R-binders
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| what is the process of B12 uptake to liver or tissue? | ingest->binds to transcobalamin I->pancreatic enzymes cleave->binds to intrinsic factor->cleave in ileum->transcobalamin II takes to liver or tissue
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| what are the 2 reactions that require B12 as a cofactor? | conversion of homocysteine to methionine; conversion of methylmalonyl-CoA to Succinyl CoA
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| Conversion of methylmalonyl-CoA to succinyl CoA requires what B12 form? | adenosylcobalamin
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| Conversion of homocysteine to methionine requires what B12 form? | methylcobalamin
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| is methionine an essential amino acid? | yes
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| what is most important function of SAM? | to methylate nucleotides (turns them off)
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| what disease is associated with hyperhomocysteinemia? | cardiovascular disease
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| what are 3 enzymatic causes of hyperhomocysteinemia? | Met synthase, MTHFR, and cystathionine synthase mutations
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| PLP is derived from what vitamin? | B6
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| how can homocysteine levels be reduced? | B6, B12, and folate supplements
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| macrocytic anemia can result from what deficiency? why? | B12 and folate; reduced nucleotides leads to less cellular dividing
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| in addition to macrocytic anemia, what else can occur in B12 deficiency? why? | neurological symptoms; need B12 to make methionine to make SAM, which is precursor for neurotransmitters
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| what is the methyl trap hypothesis? | need folate to get methylcobalamin; need B12 to recycle N5-methyl-tetrahydrofolate
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| pernicious anemia is a decrease in what? | intrinsic factor
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| normal absorption of crystalline B12 means you can not have what? | pernicious anemia
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| why is B12 deficiency seen in the elderly? | reduced gastric secretions (IF) and inadequate diet
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| what explains how B12 affects dna replication? | methyl trap hypothsis
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