Question

Metabolism can be regulated via

Group of answer choices

regulating synthesis of particular enzyme.

allosteric effectors.

feedback inhibition.

covalent modification of enzymes.

All of the above.

Answer 1

Q)

A)

REGULATORY ENZYME:-

This is an enzyme that shows the presence of other biomolecules through its response and also regulates the pathway activity.And this is done only for those pathway whose product may be need in different amount at different times (Hormone production).This enzyme will mostly exist at high concentration of low vmax due to which the activity may increase or decrease with change in substrate concentration..This enzyme will catalyse or regulate the chemical reactions.

They are commonly the first enzyme in multienzyme system.The product of a reaction is regulate by first enzyme is substrate of the second enzyme so that the cell can control the resulting product by catalysing the activity of first enzyme pathway.

There are many ways to activate or deactive this enzyme.But that require extra activation process and also need to pass through some amount of modifications in order to become an functional for instance regulatory enzymes.

This regulatory enzyme by controlled activation is are of two types that are

1.Allosteric enzyme

2.Covalent modulated enzyme.

ALLOSTERIC ENZYME (EFFECTOR):

This enzyme contain two binding sites that are : The substrate and the effectors.

Effector are small molecules which modulate the enzyme activity they may function through reversible,non covalent binding of regulatory metabolite in allosteric site.Allosteric site is an in active site.

When this effectors binds the metabolites dont participate in any catalysis directly but they are essential.They may lead to some sort of conformational changes in concrete part of enzyme.And this changes cause the overall conformation of active site and causing modification on the activity of reaction.

Properties :-

They are generally large in mass than any other enzymes.Different than having single subunit enzyme.They contain multiple subunits which contain active sites and regulatory molecule binding sites.

Based on modulation they are classified into two types that are

1)Homotropic allosteric enzyme

2)Heterotorpic allosteric enzyme

FEEDBACK INHIBITION:-

In some multienzyme system the end product will inhibit the enzyme when its concentration is above the requirement of the cell.So that the velocity of the reaction can be controlled by the amount of the product which is needed by the cell.

It is one of the most important fucntion of the proteins.Due to this a cell is able to know whether the amount of product is enough for its subsistenece or it may have lack of product.The cell is able to react to this kind of situation in mechanic way and also help to solve the problem related to amount of product.

The example of this inhibition in human is protein aconitase.Whenever cells need iron this enzyme loses the iron molecules and form changes.When ever this happen the protein aconitase changes to IRPF1 a translation repressor or mRNA stablizers that repress the formation of iron binding protein.

COVALENTLY MODULATED ENZYMES:-

The active and in active form of enzymes are altered due to an covalent modification of their structures that is catalysed by other enzymes.This type of regulation will consists of an addition or elimination of molecule which can be attached to the enzyme protein.The most important group that works as an modifiers is phosphate ,methyl, uridine,adenine,adenosine diphosphate ribosyl.They are joined to or eliminated from the protein by the help of other enzymes .The most remarkable covalent modification is phosphorylation .Serine, Threonine, Tyrosine are the common amino acids which participate in covalent modification and are used to control the enzyme catalytic activites.

Kinase and Phosphase are most commonly known enzymes which affects this modification and result in shifting of conformation of binding affinity to substrate.

Phosphorylation:-

This is an addition phosphate group to proteins which is most frequent regulatory modification mechanism in cell.This process may takes place either in prokaryotic or eukaryotic cells.Because of the frequency the phosphorylation is most important in regulatory pathway of cells.