A mutant thioredoxin from Escherichia coli tsnC 7007 that is nonfunctional as subunit of phage T7 DNA polymerase.

摘要: Thioredoxin was purified to homogeneity from the Escherichia coli mutant tsnC 7007 that is defective in phage T7 DNA replication and previously shown contain a missense thioredoxin. Tryptic peptide maps of reduced carboxymethylated thioredoxin combined with amino acid sequence analysis revealed one substitution; Gly-92 exchanged an aspartic residue protein. The gave no activity gene 5 protein complementation active polymerase. It competitively inhibited wild type formed complex retained by antithioredoxin Sepharose. has catalytic reductase, ribonucleotide or as disulfide reductase. apparent Km value substrate for reductase increased 3-fold relative normal thioredoxin, Vmax decreased 7-fold. position GLy-92 known three-dimensional structure thioredoxin-S2 correlated changed functional properties substituted