Qhov sib txawv tseem ceeb ntawm purine thiab pyrimidine synthesis yog tias purine synthesis tshwm sim feem ntau ntawm txoj kev khaws cia thaum pyrimidine synthesis tshwm sim feem ntau ntawm De novo txoj kev.
Purine thiab pyrimidine yog cov hauv paus muaj nitrogen. Purines muaj rau-tus tswv cuab thiab tsib-tus neeg koom nrog nitrogen-muaj nplhaib fused rau ib leeg. Pyrimidines tsuas muaj rau lub nplhaib uas muaj nitrogen. Purines thiab pyrimidines yog qhov tseem ceeb ntawm nucleotides uas tsim cov nucleic acids: DNA thiab RNA. Ntxiv mus, ATP yog lub zog txiaj, thaum UTP thiab GTP kuj yog lub zog. Yog li, purines thiab pyrimidines yog lub zog loj. Lawv yog cov precursors rau synthesis ntawm nucleotide cofactors xws li NAD. Purines thiab pyrimidines yog tsim los ntawm ob txoj hauv kev tseem ceeb: kev khaws cia thiab De novo txoj hauv kev. Nyob rau hauv txoj kev khaws cia, purines thiab pyrimidines yog synthesized los ntawm intermediates los ntawm txoj kev degradative. Nyob rau hauv De novo txoj kev, purines thiab pyrimidines yog synthesized los ntawm cov yooj yim molecules, tshwj xeeb tshaj yog los ntawm amino acid precursors.
YPurine Synthesis yog dab tsi?
Purines yog ob lub nplhaib carbon nitrogen. Lawv muaj 6-tus tswvcuab thiab tsib-tus tswvcuab uas muaj nitrogen-muaj nplhaib fused ua ke. Muaj plaub purine hauv paus. Adenine thiab guanine yog ob lub purines koom nrog hauv kev tsim cov nucleotides rau nucleic acids. Hypoxanthine thiab xanthine yog lwm ob purines uas tsis koom nrog nucleotides tab sis tseem ceeb rau kev sib txuas thiab degradation ntawm purine nucleotides.
Daim duab 01: Purine Synthesis
Purines yog synthesized li ribonucleotides. Purine synthesis tshwm sim ntawm ob qho tib si khaws cia thiab De novo txoj hauv kev. Hauv De novo txoj kev, IMP yog thawj cov khoom tsim, thiab tom qab ntawd nws hloov mus rau AMP lossis GMP. De novo txoj kev siv tag nrho glycine molecule (atoms 4, 5, 7), amino nitrogen ntawm aspartate (atom 1), amide nitrogen ntawm glutamine (atoms 3, 9), cov khoom ntawm lub pas dej folate-ib-carbon (atoms 2)., 8), carbon dioxide, ribose 5-P los ntawm qabzib thiab lub zog los ntawm ATP. Purine synthesis ntawm txoj kev khaws cia yuav tshwm sim nrog kev siv 5-Phosphoribosyl-1-pyrophosphate (PRPP). Lub enzyme hu ua phosphoribosyltransferases (PRT) catalyzes lub salvaging ntawm purines.
YPyrimidine Synthesis yog dab tsi?
Pyrimidines yog ib lub nplhaib carbon-nitrogen. Lawv tsuas muaj rau lub nplhaib uas muaj nitrogen. Muaj plaub pyrimidines li thymine, uracil, cytosine thiab orotic acid. Uracil pom tsuas yog hauv RNA. Cytosine muaj nyob rau hauv ob qho tib si DNA thiab RNA thaum thymine tsuas pom nyob rau hauv DNA. Zoo ib yam li purine synthesis, pyrimidine synthesis kuj tshwm sim ntawm ob qho tib si khaws cia thiab de Novo txoj hauv kev.
Daim duab 02: Pyrimidine Synthesis
Pyrimidine De novo synthesis yog yooj yim dua li purine synthesis vim pyrimidine molecules yooj yim. Glutamine's amide nitrogen thiab carbon dioxide muab atoms 2 thiab 3 ntawm lub nplhaib pyrimidine. Lwm plaub atoms ntawm lub nplhaib yog muab los ntawm aspartate. PRPP muab cov piam thaj-phosphate ib feem ntawm cov molecule. Salvaging pyrimidines yog catalyzed los ntawm nucleoside phosphorylase (uridine phosphorylase thiab deoxythymidine phosphorylase) thiab nucleoside kinases (thymidine kinase thiab uridine kinase).
Dab tsi zoo sib xws ntawm Purine thiab Pyrimidine Synthesis?
- Ob leeg purine thiab pyrimidines yog synthesized li nucleotides.
- Purine thiab pyrimidine synthesis tshwm sim ntawm kev khaws cia thiab De novo.
- Hauv De novo synthesis rau ob qho tib si purine thiab pyrimidine synthesis, cov piam thaj-phosphate ntawm cov molecule yog muab los ntawm PRPP.
- Tib neeg feem ntau yog nyob ntawm qhov kev sib txuas endogenous ntawm purines thiab pyrimidines.
- Glutamine thiab aspartate yog ob amino acid precursors xav tau rau de novo synthesis ntawm ob nucleotides.
Qhov txawv ntawm Purine thiab Pyrimidine Synthesis yog dab tsi?
Purine synthesis feem ntau tshwm sim ntawm txoj kev khaws cia, thaum pyrimidine synthesis tshwm sim los ntawm txoj kev de novo. Yog li, qhov no yog qhov sib txawv tseem ceeb ntawm purine thiab pyrimidine synthesis. Ntxiv mus, pyrimidine synthesis yog ntau yooj yim dua li purine synthesis vim pyrimidine yog ib qho yooj yim molecule tshaj purine.
Gurthermore, glycine yog ib qho amino acid precursor rau purine synthesis, thaum glycine tsis koom nrog pyrimidine synthesis.
Hauv qab infographic tabulates ib sab ntawm qhov sib txawv ntawm purine thiab pyrimidine synthesis.
Summary – Purine vs Pyrimidine Synthesis
Purines thiab pyrimidines yog ob hom nitrogen-muaj hauv paus. Ob leeg yog cov molecules tseem ceeb uas yog synthesized li nucleotides ntawm ob qho tib si khaws cia thiab de novo txoj kev. Feem ntau cov purines yog synthesized ntawm txoj kev cawm seej thaum feem ntau pyrimidines yog synthesized de novo. Ntxiv mus, pyrimidine synthesis yog ntau yooj yim dua li purine synthesis. PRPP yog xav tau rau ob qho tib si purine thiab pyrimidine synthesis. Yog li, qhov no qhia txog qhov sib txawv ntawm purine thiab pyrimidine synthesis.
