Question

Determine whether these phrases or examples describes a thioester, a reduced cofactor, or phosphorylated compounds:

- these compounds accept electrons during the oxidation of the substratea; energy is released when they are oxidized

- the sulfur-carbon bond is hydrolyzed

- these compounds yield HPO4^(2-) upon hydrolysis

- acetyl CoA

- NADH

- phosphoenolpyruvate

Answer 1

Thioester (-C(=S)-O-): The bond between the carbonyl carbon atom and the sulfur atom is broken during hydrolysis, and free energy is released. Coenzyme A is a thioester.

Reduced Cofactors: NAD+, FAD, and ubiquinone (coenzyme Q) accept electrons and hydrogen, forming reduced cofactors (NADH, FADH2, and ubiquinol) that store free energy from the oxidation of substrates.

Phosphorylated compounds: Contain phosphate groups. Large amounts of free energy are generate by hydrolysis, which results in the cleavage of HPO4^2-. Phosphocreatine, guanosine triphosphate(GTP), phosphoenolpyruvate, and 1,3-bisphosphoglycerate.

Final Answers: