DNA聚合酶( DNA polymease) 3·→5核酸外切 Template Mismatched 3 A 3 3→5 Exonuclease hydrolysis site DNA olvmerase
3'→5'核酸外切 2. DNA聚合酶(DNA polymease)
(四)参与复制的酶和蛋白质 DNA的复制 Every cell contains several different nucleases ( as), belonging to two broad classes: exonucleases 核酸外切酶) and endonucleases(核酸內切酶). Exonucleases degrade nucleic acids from one end of the molecule.核酸外切 Exonucleases degrade nucleic acids from one end of the molecule. many operate in only the 5 3 or the 3-5 direction removing nucleotides only from the 5' or the 3 end, respectively, of one strand of a doublestranded nucleic acid or of a single-stranded dna
Every cell contains several different nucleases (核 酸酶), belonging to two broad classes: exonucleases (核酸外切酶)and endonucleases (核酸内切酶). Exonucleases degrade nucleic acids from one end of the molecule. 核酸外切 Exonucleases degrade nucleic acids from one end of the molecule. Many operate in only the 5 '→ 3 ' or the 3'→5' direction, removing nucleotides only from the 5' or the 3' end, respectively, of one strand of a doublestranded nucleic acid or of a single-stranded DNA. (四)参与复制的酶和蛋白质 一.DNA的复制
(四)参与复制的酶和蛋白质 DNA的复制 Endonucleases can begin to degrade at specific internal sites in a nucleic acid strand or molecule, reducing it to smaller and smaller fragments. A few exonucleases and endonucleases degrade only single stranded DNA. There are a few important classes of endonucleases that cleave only at specific nucleotide sequences
Endonucleases can begin to degrade at specific internal sites in a nucleic acid strand or molecule, reducing it to smaller and smaller fragments. A few exonucleases and endonucleases degrade only singlestranded DNA. There are a few important classes of endonucleases that cleave only at specific nucleotide sequences. (四)参与复制的酶和蛋白质 一.DNA的复制
Nick .DNA的复制 ① RNA or DNa Template DNA Strand polymerase I OHP dNMPs 5·→3'核酸外切 dNTPs rAMPs (PPi) Nick OH(P
5'→3'核酸外切 一.DNA的复制
(四)参与复制的酶和蛋白质 DNA的复制 DNA Replication requires many enzymes and Protein factors Replication in E. coli requires not just a single DNA polymerase but 20 or more different enzymes and proteins, each performing a specific task, The entire complex has been termed the dna replicase system or replisome. The enzymatic complexity of replication reflects the constraints imposed by the structure of dna and by the requirements for accuracy
(四)参与复制的酶和蛋白质 一.DNA的复制 DNA Replication Requires Many Enzymes and Protein Factors Replication in E. coli requires not just a single DNA polymerase but 20 or more different enzymes and proteins, each performing a specific task. The entire complex has been termed the DNA replicase system or replisome. The enzymatic complexity of replication reflects the constraints imposed by the structure of DNA and by the requirements for accuracy