Question

The behavior of allosteric enzymes a. does not play any role in feedback inhibition in metabolic pathways b. is strongly dependent on the presence of metal ions c. is related to their ability to hydrolyze themselves d. depends on changes in their quaternary structure on binding of substrates or inhibitors

Answer 1

Answer:

The correct answer is d

Explanation:

Allosteric enzymes have multiple binding sites to different ligands called allosteric sites (different from the active site), these ligands can modify their kinetic properties. They are generally made up of more than one polypeptide chain, and have a quaternary structure, an enzyme with a quaternary structure can bind more than one substrate molecule. An allosteric enzyme is an enzyme whose activity is regulated by an allosteric center, which is a site, other than the active center of the enzyme, to which a regulator (called an allosteric regulator) binds in a reversible and non-covalent manner. The binding of this regulator modifies the three-dimensional structure of the enzyme and affects the configuration of the active site, thus increasing or decreasing its activity, depending on the case. The allosteric sites present in regulatory enzymes is where allosteric effectors or inhibitors are attached, causing a conformational change in the substrate binding site or catalytic site, thus regulating enzyme activity.

Answer 2

Answer:

d. depends on changes in their quaternary structure on binding of substrates or inhibitors

Explanation:

Allosteric enzymes are oligomeric proteins composed of subunits or polypeptidic chains. They have a quaternary structure -many subunits and active sites- and express two states, R and T. Both states establish an equilibrium, with or without a joint ligand.

When the transition from one state to the other occurs, symmetry is conserved, but the affinity of a site to a ligand is altered. When a substrate joins one of the sites, it affects other binding sites.

Allosteric enzymes can change their conformation, exhibiting active and inactive conformations as a result of substrate binding at the activated center and regulatory molecules at other binding sites -allosteric centers-.