FIGURE 7.
Midpoint redox potential of AtAMY3 at pH 7. 9. The ambient redox potential (Eh), adjusted by defined ratios of DTToxidized/DTTreduced, ranged from −270 to −420 mV. Preoxidized AtAMY3 protein (10 μg) was incubated in Tricine/NaOH buffer containing 20 mm total DTT in different dithiol/disulfide ratios for 2 h prior to assaying activity. The midpoint redox potential at this pH (Em, 7.9) was calculated by fitting the Nernst equation, and the error is the S.E. calculated from three replicate experiments. PNP, para-nitrophenol.