DNA toposisomerase I is a key nuclear enzyme that interconverts supercoiled DNA to the required topological conformations for normal DNA replication and transcription. This enzyme is the target antigen for the so-called Scl-70 autoantibodies. Scl-70 antibodies are a specific marker in Scleroderma patients (specificity 98-100%) and are associated with the presence of diffuse skin involvement and pulmonary fibrosis.
In human tissues the DNA topoisomerase I is initially synthesized as a protein with 100 kDa molecular weight. Most of this precursor is then proteolytically processed to a species with 70 kDa molecular weight from which the Scl-70 antigen has derived its name.
DNA Topoisomerase-I Human Recombinant produced in SF9 is a glycosylated, polypeptide chain having a molecular mass of 91,576 Dalton (excluding glycosilation) 102 kDa total mass. The TOP1 is expressed with a -6xHis tag and purified by proprietary chromatographic techniques.