In vitro and in vivo characterization of thioredoxin
Ile-75 variants. The variants are listed as shown in the bottom of each
panel. A, redox potentials of thioredoxin and mutants except for the
I75C and I75P mutants. Reduced I75C and I75P are too rapidly oxidized by air
to allow for an accurate measurement of redox potential. B, in vitro
reductase activity of thioredoxin and mutants, insulin reduction activity
using DTT as the reducing source. C, in vitro reductase activity of
thioredoxin and mutants, insulin reduction activity using NADPH with
thioredoxin reductase as the reducing source. D, in vivo reductase
activity of thioredoxin and mutants as measured by copper sensitivity. The
gradient indicates a serial dilution of trxA null cells harboring
thioredoxin and its variants (from 1 to 10-6 OD).