第二十章 核苷、核苷酸和核酸 Nucleosides, nucleotides and nucleic acids
第二十章 核苷、核苷酸和核酸 Nucleosides, Nucleotides, and Nucleic Acids
核酸中的碱基( Base in nucleic acids) Nucleic acid DNA—— Deoxyribonucleic acid RNA--Ribonucleic acid basel basel 0、|- glycosidic bond -β glycosidic bond < ribose 2-deoxy-ribosel o OH basel basel OH RNA DNA
核酸中的碱基(Base in Nucleic Acids) DNA——Deoxyribonucleic acid RNA——Ribonucleic acid Nucleic acid base O O O P O O O- base O O O P O O- base O O O P O O O- base O O O P O O- OH OH RNA DN A β-glycosidic bond β-glycosidic bond ribose 2-deox y -ribose
核酸中的碱基 Base in nucleic acids) Nucleoside base sugar Nucleotide= base sugar phosphate Nucleic acid polynucleotide Nucleotide sequence= Base sequence The bases in dna and rna NH NH 2 NH NH NO Adenine(A) Guanine(G)Cytosine( C) Thymine(r) Uracil(t (in DNA) (in RNA) Purine imidine
核酸中的碱基(Base in Nucleic Acids) Nucleoside = base + sugar Nucleotide = base + sugar + phosphate Nucleic acid = polynucleotide Nucleotide sequence = Base sequence The bases in DNA and RNA N N N H N NH 2 NH N N H N O NH 2 A denine(A ) Guanine(G) Purin e N N H NH 2 O NH N H O O NH N H O O Cytosine(C) Thy mine(T) U racil( U ) Pyrim idine (in DNA) (in RNA)
核酸中的碱基( Base in nucleic acids) Why DNa contains T instead of U? 2 NH n tautomerization NH H,O NH NO Cytosine(C Uracil(U) Thymine(t) Base pairing in dna:A=T,G≡T— double helix H N-H H H一 sugar N sugar sugar O H—N sugar H thymine adenine cytosine guanine
核酸中的碱基(Base in Nucleic Acids) Why DNA contains T instead of U? N N H NH 2 O Cytosine(C) NH N H O O Uracil(U) NH N H NH O tautomerization H 2 O NH N H O O Th y mine(T) Base pairing in DNA: A = T, G ≡ T —— double helix N N O O N N N N N N N O N N N N H H H N H sugar sugar H H O H N H sugar sugar thy mine adenine cytosine guani n e
核酸中的碱基( Base in nucleic acids) 思考题:嘌呤和嘧啶都存在互变异构的变化,请 尝试写出它们各自的互变异构结构,并回答这 种互变异构对于碱基配对将产生什么影响?pH 改变对于碱基的配对有无影响,为什么? H N-H……O、N sugar sugar sugar sugar C…… namine adenine cytosine guanine
核酸中的碱基(Base in Nucleic Acids) 思考题：嘌呤和嘧啶都存在互变异构的变化，请 尝试写出它们各自的互变异构结构，并回答这 种互变异构对于碱基配对将产生什么影响？pH 改变对于碱基的配对有无影响，为什么？ N N O O N N N N N N N O N N N N H H H N H sugar sugar H H O H N H sugar sugar thy mine adenine cytosine guani n e
ATR NH 2 0=P~0=P~0=P=O OH OH The structure of atp
ATP N N N N NH2 O P O O O P O O O P~ O O O ~ O OH OH The structure of ATP
ATP—能量转换中间体 光合磷酸化及氧化磷酸化 ADP 储能过程 耗能过程 ATP 运动、输送、生物合成等生命过程
ATP —能量转换中间体
ATP大大移动平衡反应 ATP可使与之相偶联的平衡反应向生成 物方向的速率提高108倍, B △G0=+167kJmo-1 K A+ATP+H2O—>B+ADP+Pi △GO=167+(-30.5)=-138kJmo|-1
ATP — 大大移动平衡反应 ATP可使与之相偶联的平衡反应向生成 物方向的速率提高108倍， A B ΔGӨ= +16.7 kJ·mol-1 A ATP H O B ADP Pi eq + + 2 ⎯⎯→⎯ + + K ΔGӨ=16.7+（-30.5）= -13.8 kJ·mol-1
ATP一磷酸化剂 OH 0-P-o OH > OH ATP OH > OH ADP HO OH OH
ATP — 磷酸化剂 O OH OH HO OH OH + ATP O OH OH HO O OH P O O O + ADP
DNA的双螺旋结构 CHaOs 2.8 N一H 2.9 h-n 3.0 A N-3.0A-H sugar g uga sugar 2.9 thymine adenine cytosine guanine
DNA的双螺旋结构