NUCLEOTIDES Flashcards Preview

#‼️BIOCHEMISTRY - PLE TOPNOTCH 2020 > NUCLEOTIDES > Flashcards

Flashcards in NUCLEOTIDES Deck (35)
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1

Structural analog of folate, selectively inhibits bacterial dihydrofolate reductase

Trimethoprim

2

Affected enzyme in Severe Combined Immunodeficiency Syndrome (SCID) 

Adenosine Deaminase 

3

Donors of atoms for PYRIMIDINE SYNTHESIS

  • Glutamine (Q)
  • Aspartate (D)
  • CO2

4

  • Enzyme Deficiency: HGPRT
  • Clinical Presentation:
    • ↑ PRPP and uric acid leads to gout
    • Self-mutilation, mental retardation o X-linked disease

LESCH-NYHAN SYNDROME

5

Synthesis of Purine 

6

7

o Accumulation of deoxyadenosine derivatives (↑ dATP) inhibits ribonucleotide reductase, leading to lack of DNA synthesis in immune cell precursors

o May present as severe combined immunodeficiency

o Absent thymus, no T-cell or B-cell production

(lymphocytopenia)

o Death before age 2 because of overwhelming infection

o Treat with bone marrow transplant, gene therapy

ADENOSINE DEAMINASE DEFICIENCY

8

How many rings does a pyrimidine have?

1

9

NucleoSides

BS: Base + Sugar only

10

rate limiting enzyme for PYRIMIDINE SYNTHESIS

Carbamoyl phosphate synthetase II

11

Donors of atoms of PURINE SYNTHESIS

  • glutamine (Q) 
  • Aspartate (D) 
  • CO2
  • Glycine (G) 
  • N10-formyltetrahydrofolate (Vit B9) 

12

Nucleotides composition

BSP: Base + Sugar + Phosphate.

13

Reversible inhibitor of IMP dehydrogenase, depriving T and B lymphocytes of nucleic acids

Mycophenolate

14

Purine Salvage Pathway

15

• Converts dUMP to thymine

• Cofactor: N 5 ,N 10 -methylene tetrahydrofolate

• Inhibited by 5-fluorouracil

Thymidylate synthase

16

Pyrimidine synthesis

17

Metabolically converted to 5-FdUMP, which inhibits thymidylate synthase

5-fluorouracil

18

• Converts ribose 5-phoshate to its activated form, 5- phosphoribosyl-1-pyrophosphate (PRPP)

• Energy requirement: ATP → AMP 

PRPP is the donor of ribose 5-phosphate of nucleotides, whether they are synthesized de novo or through salvage patwhays

PRPP Synthase 

19

  • Inhibits xanthine oxidase
  • Non-purine inhibitor of xanthine oxidase

Allopurinol

Febuxostat

20

inhibit dihydropteroate synthase

Sulfonamides

21

  • Enzyme Deficiency: Glucose 6-phosphatase
  • Clinical Presentation:
    • ↑ ribose 5-phosphate leads to purine overproduction and hyperuricemia, and thus, gout

VON GIERKE DISEASE

*G6Phosphatase is needed in glycogenolysis/ gluconeogenesis in the liver for G6P to be converted to G (glucose). If that enzyme is missing, G6P will be shunted towards HMP (so dadami R5P na pwede pang produce ng nucleotides eventually madami dami need idegrade → hyperuricemia)

22

connects base to sugar 

B-N-glycosidic bond 

23

24

Affected enzyme in Lesch nyhan Syndrome 

HGPRT

25

How many rings does a purine have?

2

26

bond that joins 2 nucleotides; condensation reaction; dehydration reaction 

Phosphodiester bond 

27

connects Phosphate to Sugar 

Phosphoester Bond 

28

29

parent molecule of purine synthesis

Inosine monophosphate (IMP)

30

what are the common substrates for Purine and pyrimidine synthesis?

• Glutamine

• Aspartate

• Carbon dioxide