Fig. 3.

Different behavior of insulin precipitation when reduced by Trx1 or TXNL1. In the upper part of the figure raw absorbance traces at 340 nm are shown from reactions with Trx1- (orange) and TXNL1- (purple) driven insulin reduction assays ran in parallel. Both reaction mixtures contained 300 μM NADPH, 10 nM TrxR1 and either 10 μM Trx1 or TXNL1, with the control reaction (grey) containing all components listed except for a Trx-fold protein. As is clear from the traces, inclusion of both Trx1 and TXNL1 yield an initial decrease of absorbance at 340 nm that is due to NADPH consumption, while in the case of the Trx-driven reaction but not with TXNL1, the absorbance starts to increase in an irregular manner at later time points due to insulin precipitation (as indicated on top). The lower part of the figure shows a photo of the corresponding microtiter plate wells after completion of the assay, illustrating the apparent turbidity due to insulin precipitation only seen after the Trx1-driven reaction. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)