PMID-sentid Pub_year Sent_text comp_official_name comp_offsetprotein_name organism prot_offset 9056490-3 1997 With repeated cycles of freezing and thawing as a first step, the purification of the recombinant ch-DHFR to homogeneity requires only one further step, gel filtration on a Sephadex G-75 column with 85-90% enzyme recovery, two to three times higher than that obtained with the commonly used affinity chromatography on a methotrexate-Sepharose column. Sepharose 333-342 dihydrofolate reductase Escherichia coli 101-105 7969266-7 1994 Recombinant bifunctional enzyme and the DHFR domain have been purified by methotrexate-Sepharose chromatography to yield 1-2 mg of active DHFR-TS per litre of culture. Sepharose 87-96 dihydrofolate reductase Escherichia coli 40-44