(Solved): The muscle enzyme lactate dehydrogenase catalyzes the reaction NADHandNAD+are the reduced ...

The muscle enzyme lactate dehydrogenase catalyzes the reaction $${\mathrm{NADH}}_{\text{and }}{\mathrm{NAD}}^{+}$$are the reduced and oxidized forms, respectively, of the coenzyme NAD. Solutions of $$\mathrm{NADH}$$, but not $${\mathrm{NAD}}^{+}$$, absorb light at $$340\mathrm{nm}$$. This property is used to determine the concentration of NADH in solution by measuring the amount of light absorbed by the solution at $$340\mathrm{nm}\left({\mathrm{A}}_{340}\right)$$ spectrophotometrically. How would $${\mathrm{A}}_{340}$$ change as a consequence of lactate dehydrogenase activity. Assume that the assay media contains only pyruvate and $$\mathrm{NADH}$$ at the beginning of the experiment. $${\mathrm{A}}_{340}$$ would decrease as pyruvate is reduced to lactate. $${\mathrm{A}}_{340}$$ would remain unchanged as pyruvate is reduced to lactate. $${\mathrm{A}}_{340}$$ would increase as pyruvate is reduced to lactate. Measuring $${\mathrm{A}}_{340}$$ would be insufficient to quantitatively measure lactate dehydrogenase activity.