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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

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第十二章 核酸的降解和核苷酸代谢. 主要内容:. 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. 主讲老师:华南师范大学生命科学学院      陈文利. 核酸. 核苷酸. 核苷 + Pi. 碱基 + 戊糖 -1-P. 一、核酸的分解代谢. 概况:. (一)核酸的酶解. 核酸酶(磷酸二酯酶). 核酸内切酶: DNase 、 RNase. 核酸外切酶:蛇毒磷酸二酯酶、牛脾磷酸二酯酶. (二)核苷酸的分解代谢. 核苷酸酶(磷酸单酯酶). 专一性的磷酸单酯酶 : 3ˊ- 核苷酸酶 , 5ˊ- 核苷酸酶. - PowerPoint PPT Presentation

Text of 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

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