Quick adjustment

slow adjustment

1. "Pseudosubstrate" sequence (regulatory subunit) The active site of the catalytic subunit → prevents substrate binding and inhibits enzyme activity. 2. After the effector molecule binds to the subunit, the "pseudo-substrate" sequence conformation changes, releasing the catalytic subunit and exerting a catalytic effect.

Allosteric effectors regulate subunits → the tertiary and quaternary structures of enzyme molecules interconvert between the "T" conformation and the "R" conformation, affecting enzyme activity

Changes in intracellular concentration can sensitively reflect the intensity of related metabolic pathways and corresponding metabolic needs. It can also change the conformation of key enzymes to affect enzyme activity, thereby regulating the intensity and direction of corresponding metabolism to coordinate related metabolism and meet corresponding metabolic needs. .

Feedback mechanism - The accumulation of metabolic end products indicates that the metabolism is too strong and exceeds the demand. The key enzymes of the metabolic pathway can often be allosterically inhibited, thereby reducing the intensity of the entire metabolic pathway and avoiding the production of more products than needed.

Some metabolic intermediates can allosterically regulate the key enzymes of multiple related metabolic pathways, so that these metabolic pathways can proceed in a coordinated manner.

Mainly: phosphorylation and dephosphorylation

① The vast majority of key enzymes regulated by chemical modifications have two forms, inactive and active. They can be covalently modified and transformed into each other under the catalysis of two different enzymes. Enzymes that catalyze interconversion are controlled in vivo by upstream regulatory factors such as hormones.

② The chemical modification of enzymes is an enzymatic reaction catalyzed by another enzyme. One molecule of catalytic enzyme can catalyze the covalent modification of multiple substrate enzyme molecules, with strong specificity and amplification effect.

③Phosphorylation and dephosphorylation are the most common enzymatic chemical modification reactions.

④ Enzymes that catalyze covalent modifications themselves are often subject to allosteric regulation and chemical modification, and are coupled to hormone regulation to form signaling molecules (hormones, etc.), signal transduction molecules and effector molecules (key enzymes regulated by chemical modifications). ), making the regulation of intracellular enzyme activity more precise and coordinated.

Affects transcription

Enzyme inducers (substrates or analogues)

Enzyme inhibitors (metabolites)

way