Biochem - Nucleotide Synthesis

Front 1

Intermediate in De Novo purine and pyramidine synthesis and number of ATP needed to create

Back 1

Purine- IMP- 5ATP Pyramidine - UMP 3 ATP

Front 2

How many ATP and what enzyme/cofactor makes prpp

Back 2

PRPP synthetase, requires MGg2+ and uses 1 ATP

Front 3

What is the committed step in purine nucleotide biosynthesis

Back 3

PRPP to 5' phophoribsylamine

Front 4

What are endogenous inhibitors of 5' phophoribsylamine synthesis

Back 4

AMP, IMP, and GMP

Front 5

the common precursor for purine and pyrimidine synthesis and purine salvage

Back 5

PRPP

Front 6

precursors which contribute atoms to the purine ring

Back 6

aspartate, glycine, glutamine, THF, CO2

Front 7

Main intermediate in de novo purine synthesis

Back 7

IMP

Front 8

How is AMP produced from IMP

Back 8

IMP à + H2O + NAD+ = xanthosine monophosphte à + ATP = GMP (with glutamine à glutamate as a side rxn)

Front 9

How is GMP produced from IMP

Back 9

IMP à + Aspartic acid +GTP = adelylosuccinate (minus fumarate) = AMP

Front 10

What does methotrexate inhibit

Back 10

the reduction of dihydrofolate to tetrahydrofolate which is catalyzed by dihydrofolate reductase thereby limiting the amt of tetrahydrofolate, a coenzyme necessary in the rxns leading from PRPP  IMP

Front 11

What is the role of ADA in SCID

Back 11

ADA deficiency results in an accumulation of adenosine which is converted to ribonucleotides and this increase causes ribonucleotide reductase to become inactivated preventing DNA synthesis and cell proliferation. This causes Severe Combined Immunodeficiency disease

Front 12

What is the role of xanthine oxidase in gout

Back 12

Xanthine is oxidized by XO to form uric acid. Gout is the accumulation of uric acid. Drugs to counter gout target XO

Front 13

What is HGPRT and what is it's role in Lesch-Nyhan Syndrome

Back 13

Involved in the salvage pathway of purines, reattaches the purine base back to PRPP. LN syndrome has deficiency of HGPRT so it cannot salvage hypoxanthine or guanine so the individual gets too much uric acid. Increases PRPP levels and decreases IMP and GMP levels. Causes an increase in de novo purine synthesis.

Front 14

precursors which contribute atoms to the pyramidine ring

Back 14

glutamine, CO2 and aspartic acid

Front 15

main intermediate in de novo pyramidine synthesis

Back 15

UMP

Front 16

What is the enzyme responisible for UMP

Back 16

UMP synthase from OMP

Front 17

Describe the reaction catalyzed by thymidylate synthase and its relationship to the synthesis of DNA

Back 17

dTMP, dUMP à dTDP and dUDP and vice versa using thymidylate synthase, thymidylate synthase uses THF as the methyl group.

Front 18

How is thymidine salvaged from the free base thymine

Back 18

salvaged from free thymine and dRP by thymidine phosphorylase and thymidine kinase

Front 19

the reaction catalyzed by the enzyme ribonucleotide reductase, to make deoxyribonucleotides

Back 19

ribonucleotide reductase takes ribonucleotides and turns them into deoxyribonucleotide reductase. The protons are from 2 sulfhydryl groups on the enzyme itself by coenzyme thioredoxin. This is reduced to NADPH and thioredoxin reductase.

Front 20

the role of kinases in activation of antiviral nucleoside analogs.

Back 20

a.      Kinases turn adenosine into nucleotides and deoxyribonucleotides

Back 21

b.      They also salvage pyrimidine nucleosides that use ATP in phosphorylation