Question

The active site of an enzyme is a small portion of the enzyme molecule

What is the function of the rest of the huge molecule?

Check all that apply.

To pass through cell membranes.

To provide sites for enzyme control and regulation.

To hold the substrate in place.

To stabilize the three-dimensional structure of the enzyme.

To align the active-site functional groups that catalyze the reaction.

Answer 1

1. The active site is mainly responsible for the action of the enzyme, however the rest of the molecule seems useless but it is not, the rest of the molecule provides the solubility factor, it can make the enzyme water soluble or fat soluble, thus, it play an important role while passing the molecule from cell membrane.

2. The huge portion of enzyme also regulates the active site, since active site is formed by the complex folding of the protein, therefore any disturbance in the protein structure may lead to the change in the shape of active site, thus no longer available for the action. You must have heard about allosteric site, which are located somewhere else in the protein, if any binding occurs at that sites, the active site of the enzyme changes and it becomes useless.

3. This point is not valid to much extent as substrate binds to the active site and active sites have almost all the required functional groups to bind the substrate effective. Thus, active site hold the substrate in a right position and right conformation.

4. The huge protein undergoes folding in such a way that it remain stabilised and unaffected from the external environment. Thus, it protect the 3-D structure of protein and It also protect active site and the substrate-active site complex from external influences.

5. The folding of protein forms an active site where the functional groups are aligned in such a way that they can bind the substrate effectively and undergoes the desired changes with the help of those functional groups. The alignment of functional group at active site is because of the folding of protein.