Purified Human DNA Methyltransferase isoforms
DNA methylation at CpG sites is an essential feature of gene regulation in higher eukarya [1-3]. Methylation of cytosine residues is correlated with silenced chromatin and there is strong evidence that inappropriate methylation can disrupt normal growth control circuits . The process is mediated by enzymes called DNA methyltransferases (DNMTs) and a number of different DNMT isoforms have been identified, cloned and characterized . DNMT isoforms fall into two broad groupings: 1) Maintenance activities which preferentially act on hemi-methylated DNA, and 2) De novo activities which initiate methylation on a unmethylated DNA targets. DNMT1 is a maintenance enzyme that most likely targets replicative or nascent DNA. DNMT3 type isoforms appear to be de novo methyltransferases. Other DNMTs are now known to be active but have not been classified (DNMT2) while still other isoforms appear to possess key motifs of DNMT but lack sequences necessary for catalytic activity (DNMT3L).
Methylation, Ltd. has produced purified DNMT isoforms (for research purposes only). The enzymes are His-tagged and overexpressed in Baculovirus. Lysates are produced by sonication in the presence of protease inhibitors and the proteins affinity purified over nickel-agarose columns (eluted with imidazole buffer). Concentrations are given on the product label but usually range from 0.2 to 2 ug/ul.
The elution buffer is:
The enzymes are shipped on Dry Ice. Detailed temperature stabilization time profiles have not been performed; however, store at -20oC to -70oC and avoid repeat freeze thawing cycles (it is best to aliquot the enzyme on first thaw). The enzymes are stable for 6 months from date of shipping under these conditions.
This product is designed for research use only and not suitable nor approved for diagnostic procedures in animals or humans.
1. Robertson, K. D. (2001) Oncogene 20, 3139-355.
2. Costello, J. F., Plass , Christoph (2001) J Med Genet 38, 285-303.
3. Baylin, S., Esteller, M, Rountree, M, Bachman, K. Schuebel and Herman, G. (2001) Human Molecular Genetics 10, 687-692.
4. Liu et al., (2003) Molec. Cell. Biol. 23: 2709-2719.