Which amino acids can act as additive effectors for glutamine synthetase?

Glycine and alanine serve as additive effectors for glutamine synthetase, and their roles relate to the regulation of the enzyme's activity in response to the cellular concentrations of certain metabolites.

Glutamine synthetase is an important enzyme that catalyzes the conversion of glutamate and ammonia to glutamine, a key amino acid involved in nitrogen metabolism. The regulation of this enzyme is critical for maintaining nitrogen balance and responding to metabolic needs. The presence of glycine and alanine enhances the activity of glutamine synthetase by promoting the enzyme's conversion to a more active form, thereby increasing its substrate affinity and the overall synthesis of glutamine.

Glycine, being a small amino acid, can efficiently bind to the enzyme and induce conformational changes that facilitate the catalytic process. Alanine similarly enhances the activity by affecting substrate binding or by stabilizing the tripartite structure of the enzyme that increases its overall efficiency.

In contrast, the other options suggest that only one of these amino acids or glutamate could act as the additive effector, which overlooks the collaborative role that both glycine and alanine play in the activation of glutamine synthetase. Thus, the answer reflecting that both glycine and alanine can