What is the molecular mechanism of substrate channeling in the PDH complex? A. The swinging lipoyllysyl arm of E2 carries electrons and an acetyl group from E1 to E2. B.The active sites of E1, E2, and E3 undergo conformational changes that move products of one reaction to their next position without solvent exposure. C.Electrons and an acetyl group travel between E1 and E2 through a tunnel in E2. D. Metal ions coordinated with thiamine pyrophosphate (TPP) in E1 shield the electrons and acetyl group from scavenging by other enzymes until they reach E3.
The pyruvate dehydrogenase (PDH) complex catalyzes the oxidative decarboxylation of pyruvate to acetyl‑CoA and CO2.CO2. Multiple copies of pyruvate dehydrogenase (E1), dihydrolipoyl transacetylase (E2), and dihydrolipoyl dehydrogenase (E3) along with five cofactors form the PDH complex. Biochemists have studied the PDH complex for decades, in part due to its interesting use of substrate channeling during catalysis.
What is the molecular mechanism of substrate channeling in the PDH complex?
A. The swinging lipoyllysyl arm of E2 carries electrons and an acetyl group from E1 to E2.
B.The active sites of E1, E2, and E3 undergo conformational changes that move products of one reaction to their next position without solvent exposure.
C.Electrons and an acetyl group travel between E1 and E2 through a tunnel in E2.
D. Metal ions coordinated with thiamine pyrophosphate (TPP) in E1 shield the electrons and acetyl group from scavenging by other enzymes until they reach E3.
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