核酸怎样分解成核苷酸 核苷酸又怎样进一步分解 生物怎样合成核苷酸

DNaseRNase

: 3-, 5-

CO2NH3

AdeGua

gout

allopurinol

RNACytUra

DNAThy

1De novo synthesis IMP

IMP R-5-P5-16 :

Many steps require an activated ribose sugar

The committed step in the do novo synthesis of purine nucleotides

5-IMP5-IMP :

IMP

purine

GlnGlnazaserine6--5-6-diazo-5-oxonorleucine,DONGlnGln5 FH4amino proteinamethop terin4,10

Purine Biosynthesis (de novo)ATPGTP(A bunch of steps you dont need to know)(Inosine Monophosphate)FeedbackInhibition

The synthesis of AMP and GMP from IMP

2salvage pathway (2) phosphoribosyl transferase

(adenine phosohoribosyl transferase)(hypoxanthine-guanine phosohoribosyl transferase)

HGPRT

Lesch-Nyhan SyndromeAbsence of HGPRTaseX-linked (Gene on X)Occurs primarily in malesCharacterized by:Increased uric acidSpasticityNeurological defectsAggressive behaviorSelf-mutilation

PRPP

1UMP 1De novo synthesis : 234 , 56

The pyrimidine biosynthetic pathway

2salvage pathway

2. CMP

CTP synthesis from UTP

Biosynthesis: Purine vs PyrimidineSynthesized on PRPP

Regulated by GTP/ATPGenerates IMPRequires Energy

Synthesized then added to PRPPRegulated by UTPGenerates UMP/CMPRequires EnergyBoth are very complicated multi-step process whichyour kindly professor does not expect you to know in detail

1.

HydroxyureaSpecifically inhibits ribonucleotide reductaseInhibits DNA synthesis without affecting RNA synthesis or other nucleotide poolsCleared from the body rapidly so not used extensively in the clinic

2. dTMP UMPdTMP :12 DPMP