Question

Enzymes can be thought as being catalytic receptors that bind transition states more strongly than the substrates. DESCRIBE two features of cysteine protease mechanisms that might support this concept.

Answer 1

Solution:

The catalytic receptor aka enzyme-linked receptor is a transmembrane protein having extracellular ligand binding domain and cytosolic enzymatic domains. Connecting these two domains is an hydrophoic transmembrane domain. These proteins generally are dimeric in nature. Binding of ligand to the extracellular receptor domain activates inactive protein into active conformation this inturn activates the catalytic function of the enzymatic domain.

Cysteine proteases is an enzyme which specifically cleaves and degrade proteins. This contains the nucleophilic cysteine thiol in a catalytic triad or dyad that initiate the attack. In general condition this enzyme is in inactive zymogenic conformation. Activation of cysteine proteases through dimerization of proteolytic cleaving converts this enzyme from zymogenic inactive conformation to active conformation which then induces the degradation of downstream proteins .