Flashcards in Biochem Deck (29):
What amino acids are necessary for purine synthesis?
(also need CO2 and THF)
What is the rate limiting step of purine synthesis?
Glutamine PRPP amidotransferase
What drugs inhibit glutamine PRPP amidotransferase?
Azathioprine (6-MP prodrug)
What type of drug is azathioprine?
Azathioprine is an immunosuppressant
What are some possible toxicities of azathioprine?
What enzyme degrades 6-MP?
Xanthine oxidase...allopurinol inhibits this enzyme...FYI
When is 6-MP used?
What is needed for pyrimidine synthesis?
What is the rate limiting step of pyrimidine synthesis?
Carbamoyl Phosphate Synthetase II (CPS 2)
UMP synthase is another necessary enzyme in pyrimidine synthesis. What happens when this enzyme is deficient?
What are the signs of orotic acuduria?
Increased orotic acid in urine
Normal urine ammonia level
Megaloblastic anemia that is NOT cured with folate/B12
Ribonucleotide reductase is the enzyme that puts the d in dna. What drug inhibits this enzyme?
When is hydroxyurea used?
Sickle cell disease (increases HbF)
What are the side effects of hydroxyurea?
Bone marrow suppression
What drug inhibits the methylation of dUMP to dTMP?
Flucytosine gets converted to 5-FU
When is 5-FU used?
Basal cell carcinoma
What are the side effects of 5-FU?
When is flucytosine used?
Systemic fungal infections...given with amphotericin B
DHFR is also necessary for the methylation of dUMP. What drugs inhibit DHFR?
What enzyme is necessary for the conversion of adenosine to inosine (for the purine salvage pathway)?
Adenosine deaminase (ADA)
What is the metabolic effect of ADA deficiency?
A build up of ATP and dATP causes a feedback inhibition on ribonucleotide reductase...NO DNA synthesis
What is the medicinal effect of ADA deficiency?
SCID (No B cells or T cells)
No thymic shadow on CXR
Lesch-Nyhan syndrome is a purine salvage disease. What enzyme is deficient with this disease?
What are the s/s of Lesch-Nyhan syndrome?
P- Pissed off (aggression, self-mutilation)
R- Retardation (intellectual disability)
What cancer gene includes a MMR mutation?
What is an effect of mutated NER?
(easy to remember because UV rays cause thymine dimers...and NER fixes thymine dimers)
What syndrome is caused by a helicase mutation?
What process is mutated with ataxia telangiectasia?