FIGURE 3.

Effect of cobalamin on thioredoxin and thioredoxin reductase activity. To measure Trx activity (A), the reduction of the alpha-chain of insulin was monitored at 650 nm as described under Section “Materials and Methods.” TR activity (B) was monitored by following the reduction of 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB) at 412 nm. The activity in the control reaction corresponds to 100%. Data represent the average of two independent experiments (lines on top of bars indicate value ranges). ^∗P < 0.05, ^∗∗P < 0.01.