| Question |
Answer |
| What are the 3 main carriers of reduced one-carbon units? |
derivatives of THF acid, SAM,vit B12 |
| What are the sources of 1 carbon units? |
Ser, Gly, His, Formate, Formaldehyde |
| FH4 is derived from what vitamin? |
folic acid (folate) |
| Folate is synthesized from what 3 precursors? |
pteridine ring, PABA, glutamate |
| What is the key enzyme involve din FH4 synthesis from Folate? |
dihydrofolate reductase |
| Where are the carbon units attatched to on FH4? |
N5 or N10 |
| What AA is the major source of one-carbon groups carried by FH4? |
Ser |
| What path does His take to get to its FH4 derivative? |
His, FIGLU, 5-formimino-FH4, methenyl-FH4 |
| Glycine forms what FH4 derivative? |
methylene-FH4 |
| Formaldehyde forms what FH4 derivative? |
Methylene-FH4 |
| Formate forms what FH4 derivative? |
Formyl-FH4 |
| Reoxidation of FH4 derivatives cannot occur at what level of oxidation? |
Methyl-FH4 |
| What are the direct recipients from FH4 carbon pool? |
dUMP, purine precursors, Gly, B12 |
| dUMP is methylated to dTMP by what enzyme? |
thymidylate synthase |
| What is the source of the free carbon for dTMP formation? |
methylene-FH4 |
| What is the enzyme the catalyzes the reduction of FH2 to FH4? |
dihydrofolate reductase |
| What chemotherapy agents disrupt dTMP formation? |
Methotrexate, 5-Fluorouracil |
| What does methotrexate inhibit? |
dihydrofolate reductase |
| What does 5-Fluorouracil inhibit? |
thymidylate synthase |
| Cobalamine is also known as ______ |
Vitamin B12 |
| What is the major source of Vitamin B12? |
dietary meats, dairy |
| What proteins help vitB12 absorb from the gut? |
R-binders, Inrinsic factgors, proteases |
| What protein carriers vit B12 in the blood to the liver? |
transcobalamin II |
| What two reactions in the body involve vit B12? |
1. methyl transfer from FH4 to homocysteine to form methionine 2. methylmalonyl CoA to Succinyl CoA |
| What is the form of B12 forming methionine? |
methyl-B12 |
| What is the form of B12 forming Succinyl CoA? |
5'-adenosylcobalamin |
| What are clinical signs of B12 deficiency? |
hematopoisis and neurological signs |
| B12 hematopoietic problems cause what secondary deficiency? |
folate deficiency |
| B12 deficiency leads to neurological problems and a build up of what substance? |
Methyl-malonyl CoA |
| What is SAM? |
S-adenosyl methionine |
| SAM is synthesized from what two things? |
methionine and ATP |
| Mutations in what enzymes lead to homocysteine elevations? |
methionine synthase, n5,n10 methylene FH4 reductase, cystathionine-beta-synthase |
| Elevated homocysteine is a risk factor for what disease? |
cardiovascular disease |
| Biotin is involved in transfering what type of carbons? |
oxidized on-carbon units |
| What enzyme is coupled with biotin to move an oxidized-carbon? |
pyruvate carboxylase |
| Enzyme bound biotin is linked to what AA via an amide linkage? |
lysine residue |
| What are the recipients of one-carbon transfers via FH4? |
dTMP, ser, purines, vit B12 |
| Substantially higher doses of folate are RXed for pregnant women to prevent what new born defect? |
spina bifida |
| What is the main pathway for obtaining folate in humans? |
absorbtion from the diet |
| What category of drugs are prescribed to interfere with folate synthesis in bacterial infections? |
Sulfa drugs |
| What is considered the active form of folate? |
FH4 |
| Serine forms what FH4 derivative? |
N5,N10-methylene FH4 |
| His forms what FH4 derivative? |
N5,N10-methenyl FH4 |
| Formaldehyde is produced during the catabolism of methyl groups off of what molecules? |
choline and Epi |
Spanish 3
