说明: phiX174 was the first DNA virus discovered to have a single-stranded, circular genome. phiX174 DNA is 5386 nt in length. The DNA strand packaged into the virion is termed the “plus” strand. After entering the cell, phiX174 DNA is used as a template for minus-strand synthesis, producing double-stranded DNA. The conversion of plus DNA strands to double-stranded DNA does not require any of the phage genes to function. The double-stranded DNA can then be transcribed, resulting in synthesis of phage-encoded proteins. Synthesis of single-stranded (plus) DNA requires phage-encoded gene A protein. DNA synthesis is initiated at ori (+) and proceeds in the direction indicated. Late in infection, the single-stranded circles are encapsidated into new virions. The cycle terminates by cellular lysis, mediated by phage gene E encoded protein. The genes identified in phage phiX174 are shown on the map. All genes are transcribed clockwise. Enumeration of phage DNA begins with the last nucleotide of the unique PstI site and continues clockwise around the viral (+) strand in the 5’=>3’ direction. The map shows enzymes that cut phiX174 DNA once. Enzymes produced by Fermentas are shown in orange. The coordinates refer to the position of the first nucleotide in each recognition sequence. 特性: Purified by chromatography using proprietary patented technology. More than 90% in the supercoiled form. Isolated from E.coli HF4704 infected with phiX174 am3. For DNA sequence, sequence analysis and map creation see free on-line tool REviewer. 应用: Preparation of DNA molecular weight standards. 质量控制: DNA concentration is confirmed spectrophotometrically. Identity and homogenity of DNA is confirmed by digestion by BsuRI and HinfI, and analysis of DNA fragmentation patterns. |