1. DNA methylase from Pisum sativum.
- Author
-
Yesufu HM, Hanley A, Rinaldi A, and Adams RL
- Subjects
- Base Sequence, DNA metabolism, DNA-Cytosine Methylases genetics, Electrophoresis, Polyacrylamide Gel, Fabaceae genetics, Fabaceae growth & development, Molecular Weight, Sodium Chloride pharmacology, Solubility, Substrate Specificity, Time Factors, DNA-Cytosine Methylases metabolism, Fabaceae enzymology, Plants, Medicinal
- Abstract
DNA methylase activity was detected in nuclei from pea shoots. The enzyme can only be extracted by low-salt treatment if the nuclei are pretreated with micrococcal nuclease. Only a single enzyme was detected, and it was purified to a specific activity of 1620 units/mg of protein. It has an Mr of 160,000 on gel filtration and SDS/PAGE. Pea DNA methylase methylates cytosine in all four dinucleotides, and this is interpreted to show that it acts on CNG trinucleotides. Although it shows a strong preference for hemi-methylated double-stranded DNA, it is also capable of methylation de novo. Homologous DNA is the best natural substrate. In vitro the enzyme interacts with DNA to form a salt-resistant complex with DNA that is stable for at least 4 h.
- Published
- 1991
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