Enzyme Kinetics and Regulation (1A) Practice Test

An enzyme in glycogen breakdown is tested in vitro. Adding AMP increases activity at low substrate, consistent with a left-shifted sigmoidal curve, while $V_{max}$ is similar. Which physiological condition would most likely mimic the effect of AMP on this enzyme?

A lab compares an enzyme’s kinetics in two buffers (both pH 7.4, 37°C) for a glycolytic enzyme. Buffer A contains 1 mM Mg$^{2+}$; Buffer B contains 10 mM EDTA. In Buffer B, $V_{max}$ decreases markedly while apparent $K_m$ is similar. Which condition would most likely increase enzyme activity back toward Buffer A levels?