Catecholamines increase the secretion of insulin and glucagon via β-adrenergic mechanisms and inhibit the secretion of these hormones via α-adrenergic mechanisms

TLS Online TPP Program

#Id: 8562

#Unit 1. Molecules and their Interaction Relevant to Biology

In neither case does the inhibitor compete with the substrate for the same binding site, so the inhibition cannot be overcome by increasing the substrate concentration.

TLS Online TPP Program

#Id: 8563

#Unit 1. Molecules and their Interaction Relevant to Biology

Substrate-binding could cause a conformational change to take place in the enzyme and reveal an inhibitor binding site, or the inhibitor could bind directly to the enzyme-bound substrate. 

TLS Online TPP Program

#Id: 8564

#Unit 1. Molecules and their Interaction Relevant to Biology

TLS Online TPP Program

#Id: 8565

#Unit 1. Molecules and their Interaction Relevant to Biology

In the simplest possible model, simple linear non-competitive inhibition, the substrate does not affect inhibitor-binding. 

TLS Online TPP Program

#Id: 8566

#Unit 1. Molecules and their Interaction Relevant to Biology

Under these conditions, the reactions have an identical dissociation constant Ki , again called the inhibitor constant. 

TLS Online TPP Program

#Id: 8568

#Unit 1. Molecules and their Interaction Relevant to Biology

In the presence of a non-competitive inhibitor which will bind equally well to E or to ES- Vmax decreases but not Km