Practice Test 2

A study tested whether adding a chelating agent affects the rate of an Fe$^{3+}$-catalyzed oxidation reaction. Hypothesis: EDTA decreases the oxidation rate by binding Fe$^{3+}$ and reducing its catalytic availability. Methods: Two reaction mixtures were prepared with identical concentrations of substrate and Fe$^{3+}$ at the same pH and temperature. Condition 1: no EDTA. Condition 2: added EDTA. Product formation was tracked by absorbance. Results: The EDTA condition showed a slower increase in absorbance. Which factor most likely influences the outcome?

A lab separated two recombinant proteins by SDS-PAGE (denaturing) using a 10% polyacrylamide gel at pH 8.3 and 200 V for 30 min. Both proteins were fully reduced and treated with excess SDS. Bands were detected by Coomassie staining.

Table 1. Observed migration distance Protein | Mass (kDa) | Observed migration (mm) R | 20 | 41 S | 60 | 18

Which protein is most likely to migrate faster under these SDS-PAGE conditions, consistent with electrophoresis principles?