Fig. 4.

Lack of insulin precipitation upon reduction by TXNL1 is independent of reduction speed. (A) Kinetics of NADPH consumption followed as absorbance decrease at 340 nm are shown using either Trx1 and TrxR1 at 10 μM and 10 nM, respectively (orange) or TXNL1 and TrxR1 at 20 μM and 20 nM, respectively (purple), resulting in similar initial speeds of the reaction, as also shown in (B) that is a magnification of the shaded area in (A). The control reaction contained only 20 nM TrxR1 (grey) and all reactions contained 160 μM insulin and 300 μM NADPH. In (C) photos of the wells at different time points from assays ran as in (A) are shown, clearly visualizing precipitate formation only in the Trx1-driven reaction but not in that driven with TXNL1. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)