nucleotide oxidation

the enzyme [ ] converts ribose-5-phosphate to 5-phoshoribosyl-1-phosphate

PRPP synthetase

the enzyme [ ] converts 5-phoshoribosyl-1-phosphate to IMP

glutamine PRPP aminotransferase

the enzymes [ ] coverts IMP to GMP and eventually GDP

1) IMP dehydrogenase

2) GMP synthetase

the enzymes [ ] coverts IMP to AMP and eventually ADP

1) adenylosuccinate synthetase

2) adenylosuccinate lyase

purines have a [ ] member structure

double-ring

six-membered pyrimidine ring & 5 member imidazole ring

pyrimidines have a [ ] member ring structure

five

[ ] is the rate limiting step in de novo synthesis of purines

glutamine PRPP aminotransferase

[ ] is the rate limiting step in de novo synthesis of pyrimidine

CPS-II

the enzyme [ ] converts 2 ATP, CO2, and glutamine into carbamoyl phosphate

CPS-II

[rate-limiting step]

the enzyme [ ] converts carbamoyl phosphate into carbomyl aspartate

aspartate transcarbomyolase

the enzyme [ ] converts carbamoyl aspartate into dihydrorotate

dihydroorotase

[ closes pyrimidine ring]

the enzyme [ ] converts dihydrorotate into orotate

dihydrorotate dehydrogenase

[oxidation reaction]

the enzyme [ ] converts orotate into IMP

orotate phosphoribosyl transferase

the enzyme [ ] converts IMP into UMP

orotidylate decarboxylase

a deficiency in [ ] and [ ] leads to orotic aciduria

orotate phosphoribosyl transferase
orotidylate decarboxylase

characteristics of orotic aciduria

increased carbamoyl phosphate in liver mitochondria

an oral dose of [ ] is used to treat the bifunctional enzyme deficiency in pyrimidine biosynthesis

uridine

• restores UMP levels, UMP » UTP, inhibits CPS-II

pyrimidiine nucleotides are converted using these enzymes

ribonucleotide reductase

thimidylate synthase - adds methyl group

methylene-THF

carries one-carbon units for DNA synthesis

the end products of pyrimidine degradations are ?

Beta alanine & CO2

pyrimidine degradation pathway

CMP » cytosine » uracil » dihydroxyuracil » beta alanine & CO2

thymine » dihydrothymine » NH3 & B-aminoisobutyrate » beta alanine & CO2

purines are converted from monophosphates to di & triphosphates using ?

nucleoside monophosphate kinase

nucleoside diphosphate kinase

purine salvage pathway

hypoxanthine + PRPP » IMP + PPi

guanine + PRPP » GMP + PPi

adenine + PRPP » AMP + PPi

a deficiency in [ ] leads to Lesch-Nyham syndrome

HGPRT

[ ] is characterized by increased [ ] and de novo leading to uric acid accumulation

Lesch-Nyham / PRPP

self mutilation and [ ] are characteristics of Lesch-Nyham

gout

purine degradation

IMP » inosine » hypoxanthine » xanthine » uric acid

AMP » adenosine » inosine » hypoxanthine » xanthine » uric acid

GMP » guanosine » guanine » xanthine » uric acid

[ ] leads to SCID characterized by T & B lymphocyte immunodeficiency

ADA deficiency

[ ] leads to increased dGTP characterized by T lymphocyte immunodeficiency

PNP deficiency