Purification and properties of a pea chloroplast DNA polymerase
AUTOR(ES)
McKown, R. L.
RESUMO
A DNA polymerase has been purified >3,000-fold from the chloroplasts of pea plants by chromatography on DEAE-cellulose, phosphocellulose, single-stranded DNA-agarose, and sedimentation in a glycerol gradient. Electrophoretic analysis on polyacrylamide gels in the presence of sodium dodecyl sulfate indicates that the final fraction contained a single discernible protein band of 90,000 daltons. Gel filtration on Sephacryl S-200 and glycerol gradient sedimentation under nondenaturing conditions demonstrate that the chloroplast DNA polymerase has a native molecular mass of approximately 87,000 daltons. The purified polymerase lacks any associated nuclease activity. The enzyme activity is inhibited by N-ethylmaleimide (74% at 1.0 mM) and ethidium bromide (90% at 0.23 mM) and is resistant to aphidicolin. The purified enzyme is totally dependent on the presence of added DNA, has an absolute requirement for Mg2+ (12 mM optimal), is stimulated by K+ (120 mM optimal), and requires all four deoxynucleoside triphosphates for maximum activity. Native DNA which has been degraded to a limited extent with DNase I is the most efficient template.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=345058Documentos Relacionados
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