Source:http://linkedlifedata.com/resource/umls/id/C0012863
MSH: DNA TOPOISOMERASES that catalyze ATP-dependent breakage of both strands of DNA, passage of the unbroken strands through the breaks, and rejoining of the broken strands. These enzymes bring about relaxation of the supercoiled DNA and resolution of a knotted circular DNA duplex.,NCI: Topoisomerase II catalyzes relaxation of supercoiled DNA molecules, catenation, decatenation, knotting, and unknotting of circular DNA. The topoisomerase II reaction appears to involve crossing-over of two DNA segments. Human cells contain two topoisomerase II isozymes: alpha and beta from distinct genes. DNA topoisomerase II alpha is associated with the Pol II holoenzyme and is required for chromatin-dependent co-activation. Transcription results in superhelical tension; topoisomerase II relaxation activity is essential for productive RNA synthesis on nucleosomal DNA. (from OMIM 126430 and NCI)