Metabolism of purines and pyrimidines- exercise -

Vladimíra Kvasnicová

Purine nucleotides

a) include an aromatic cycle in the structure

b) can contain either adenine or thymine

c) include N-glycosidic bond

d) are composed of a nucleoside bound to phosphoric acid by an anhydride bond

Purine nucleotides

a) include an aromatic cycle in the structure

b) can contain either adenine or thymine

c) include N-glycosidic bond

d) are composed of a nucleoside bound to phosphoric acid by an anhydride bond

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

PURINE BASES

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

ribonucleoside deoxyribonucleoside

N-glycosidic bond

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

ribonucleotide deoxyribonucleotide

ester bond

Pyrimidine nucleotides

a) include an imidazol ring in the structure

b) include thymidine- and cytidine monophosphate

c) contain an ester bond

d) can include 3 phosphate groups in their structure

Pyrimidine nucleotides

a) include an imidazol ring in the structure

b) include thymidine- and cytidine monophosphate

c) contain an ester bond

d) can include 3 phosphate groups in their structure

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

PYRIMIDINE BASES

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

ribonucleosides deoxyribonucleoside

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed.

Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

Ribonucleotides

* N-glycosidic bond

* ester bond

* anhydride bond

Purine and pyrimidine nucleotides can be used

a) as nucleoside triphosphates for nucleic acid synthesis

b) in energy metabolism of cells

c) for activation of metabolic intermediates of saccharides and lipids

d) in enzymatic reactions: some coenzymes are nucleotides

Purine and pyrimidine nucleotides can be used

a) as nucleoside triphosphates for nucleic acid synthesis

b) in energy metabolism of cells

c) for activation of metabolic intermediates of saccharides and lipids

d) in enzymatic reactions: some coenzymes are nucleotides

Synthesis of nucleotides

a) uses products of pentose cycle

b) includes phosphoribosyl diphosphate (PRDP = PRPP) as a substrate

c) needs derivatives of folic acid

d) proceeds in a cytoplasm only

Synthesis of nucleotides

a) uses products of pentose cycle

b) includes phosphoribosyl diphosphate (PRDP = PRPP) as a substrate

c) needs derivatives of folic acid H4 –folate (THF)

d) proceeds in a cytoplasm only

pentose cycle

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

PRPP = PRDP

Synthesis of purine nucleotides

a) uses ammonia as a nitrogen donor

b) proceeds in a cytoplasm

c) can start from nucleosides produced by degradation of nucleic acids

d) includes uric acid as an intermediate

Synthesis of purine nucleotides

a) uses ammonia as a nitrogen donor

b) proceeds in a cytoplasm

c) can start from nucleosides produced by degradation of nucleic acids

d) includes uric acid as an intermediateuric acid is the end product of purine ring degradation

Obrázek převzat z http://web.indstate.edu/thcme/mwking/nucleotide-metabolism.html (leden 2007)

Synthesis of purine nucleotides

CYTOPLASM

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

AMPGMP

IMP

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

Synthesis of pyrimidine nucleotides

a) starts by the reaction: PRDP + glutamine

b) proceeds only in a cytoplasm of cells

c) includes orotic acid as an intermediate

d) includes inosine monophosphate as an intermediate

Synthesis of pyrimidine nucleotides

a) starts by the reaction: PRDP + glutamine

b) proceeds only in a cytoplasm of cells

c) includes orotic acid as an intermediate

d) includes inosine monophosphate as an intermediate

Obrázek převzat z http://web.indstate.edu/thcme/mwking/nucleotide-metabolism.html (leden 2007)

Synthesis of pyrimidine nucleotides

CYTOPLASM

mitochondrion

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

enzyme: ribonucleotide reductase+ small protein „thioredoxin“

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

Synthesis of 2-deoxyribonucleotides

Obrázek je převzat z učebnice: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley-Liss, Inc., New York, 1997. ISBN 0-471-15451-2

Synthesis of thymidine monophosphate

In a regulation of nucleotide synthesis participate:

a) 5´-phosphoribosyl-1´-diphosphate (PRDP)

b) feed back inhibition

c) enzyme carbamoyl phosphate synthetase II(synthesis of pyrimidines)

d) enzyme xanthine oxidase(synthesis of purines)

In a regulation of nucleotide synthesis participate:

a) 5´-phosphoribosyl-1´-diphosphate (PRDP)

b) feed back inhibition

c) enzyme carbamoyl phosphate synthetase II(synthesis of pyrimidines)

d) enzyme xanthine oxidase(synthesis of purines) = enzyme of purine degradation

Regulation of nucleotide synthesis

• UTP• PRPP• ATP

carbamoylphosphatesynthetase II

= cytosolic

(pyrimidines)

• IMP, GMP, AMP (allosteric inhibition)

• PRPPglutamine-PRPPamidotransferase

(purines)

inhibitionactivationregulatory enzyme

In a degradation of purine nucleotides

a) ammonia is released

b) CO2 is produced

c) the enzyme xanthine oxidase participates

d) uric acid is produced as the end product

In a degradation of purine nucleotides

a) ammonia is released

b) CO2 is produced

c) the enzyme xanthine oxidase participates

d) uric acid is produced as the end product

Degradation of purines

= „uric acid“

In a degradation of pyrimidine nucleotides

a) ββββ-amino acids are produced

b) the enzyme xanthine oxidase participates

c) orotic acid is formed

d) ammonia is produced

In a degradation of pyrimidine nucleotides

a) ββββ-amino acids are produced

b) the enzyme xanthine oxidase participates

c) orotic acid is formed

d) ammonia is produced

Degradation of pyrimidines

Principal differences between metabolism of purines and pyrimidines

CO2, NH3, β-AMK(soluble in H2O)

uric acid(poor solubility in H2O),

NH3

products of degradation

cytoplasm + 1 enzymein a mitochondrion

cytoplasmlocation of biosynthesis

a heterocyclic ring is formed first, then it reacts with PRDP

in 1st step of their biosynthesis(PRDP is the 1st substrate)

formation of N-glycosidic bond

pyrimidinespurines