co0 coo cOo HaN-C-H HaN-C-H H3N NADPH, O2 NADP, H2O CHa NADPH, O, NADP,, H. CH2 CH CH2 no NH NH NH Nitric oxide C=NH C=N-OH C=0 NH NH2 NH Arginine Hydroxyarginine Citrulline Nitric oxide (NO)is made from Arg and O, in a reaction catalyzed by nitric oxide synthase (NOS),a monooxygenase containing five coenzymes: NADP, FMN FAD, tetrahydrobiopterin, and a Fe 3+-heme (Robert F. Furchgott, Louis J Ignarro, and Ferid Murad were awarded the 1998 Nobel Prize in Medicine for revealing the role of no in the cardiovascular systems
Nitric oxide (NO) is made from Arg and O2 in a reaction catalyzed by nitric oxide synthase (NOS), a monooxygenase containing five coenzymes: NADP, FMN, FAD, tetrahydrobiopterin, and a Fe 3+ -heme. (Robert F. Furchgott, Louis J. Ignarro, and Ferid Murad were awarded the 1998 Nobel Prize in Medicine for revealing the role of NO in the cardiovascular systems)
18 Nucleotides are synthesized via either the de novo pathways orthe salvage pathways In the de novo pathway simple precursors including amino acids, PRPP, NHt, co and one-carbon units(carried on H4 folate) are used. - c In the salvage pathway the free bases and nucleosides released from nucleic acid breakdown are used
18. Nucleotides are synthesized via either the de novo pathways or the salvage pathways • In the de novo pathway simple precursors, including amino acids, PRPP, NH4 + , CO2 , and one-carbon units (carried on H4 folate) are used. • In the salvage pathway the free bases and nucleosides released from nucleic acid breakdown are used
The free bases(A, G, C, U, t) are not intermediates during the de novo synthesis: the purine ring is assembled on ribose phosphate to make AMP and GMP; the pyrimidine ring is first synthesized as orotate, which is then attached to ribose phosphate before being converted to UTP and CTP(dTMP is made from dUMP) The deoxyribonucleotides(dNDPs)are synthesized by reduction of ribonucleotides ( NDPs
• The free bases (A, G, C, U, T) are not intermediates during the de novo synthesis: the purine ring is assembled on ribose phosphate to make AMP and GMP; the pyrimidine ring is first synthesized as orotate, which is then attached to ribose phosphate before being converted to UTP and CTP (dTMP is made from dUMP). • The deoxyribonucleotides (dNDPs) are synthesized by reduction of ribonucleotides (NDPs)
19. Radioisotope tracer experiments revealed the origins of the atoms in the purine and pyrimidine rings Buchanan and Greenberg revealed this by feeding a variety of isotopically labeled compounds to pigeons (1940s) The atoms of the purine rings were found to be derived from formate, CO,, Gly, Asp, and GIn The atoms of the pyrimidine rings were found to be derived from Asp, GIn and HCO3
19. Radioisotope tracer experiments revealed the origins of the atoms in the purine and pyrimidine rings • Buchanan and Greenberg revealed this by feeding a variety of isotopically labeled compounds to pigeons (1940s). • The atoms of the purine rings were found to be derived from formate, CO2 , Gly, Asp, and Gln. • The atoms of the pyrimidine rings were found to be derived from Asp, Gln and HCO3 -
CO2 Glycine Aspartate C N C ‖C← Formate C C Formate N个A N↑N mide of glutamine Radioisotope tracer experiments revealed the origins of the ring atoms of purines
Radioisotope tracer experiments revealed the origins of the ring atoms of purines