Fig. 2.

Michaelis-Menten plots with human TXNL1 and Trx1 using insulin, l-cystine and GSSG as substrates. The initial reaction rates in reduction of either insulin (160 μM), l-cystine (250 μM) or GSSG (1 mM) were determined in assays coupled with 10 nM TrxR1 and 300 μM NADPH using increasing concentrations of either A) Trx1 or B) TXNL1, as indicated. Turnover was calculated as mol NADPH consumed per mol Se-containing TrxR1. For further experimental details, see the methods description. Values are average from three independent enzyme assays each time run with single samples and error bars show ± S.D. For the resulting calculated kinetic parameters, see Table 2.