Enzymes

ENZYMES

Enzymes are biological catalysts which influence biochemical reactions.
All enzymes are proteins only all proteins are non enzymes because at that spot are proteins other than enzymes.

Ribozymes: These are the Nucleic acids (RNA) that bear similar enzymes.
The heart together with mortal on which the enzyme acts is known every bit substrate.
Enzymes are specific. i.e, Each enzyme tin exclusively acts on a specific substrate. 
The third construction of an enzyme has about crevices (pockets) called ‘active site’ into which the substrate fits.
Inorganic catalysts function at high temperature & pressure. But enzymes larn damaged at high temperature. (> 400 C).

Thermophilic organisms accept enzymes which are stable at high temperature (up to 80-900 C).
Carbonic anhydrase is the fastest enzyme. It accelerates the next reaction 10 1000000 times.

CO2 + H2O carbonic anhydrase H2CO3

In the absence of enzyme, exclusively 200 molecules of H2CO3 are formed inwards an hour. In the presence of carbonic anhydrase nigh 600,000 molecules are formed per second.

Nature of enzyme activity (catalytic cycle)

The enzyme activity on substrate is similar to a Lock-Key action. It involves the next steps:

E + southward → ES → EP → eastward + P

Step 1: The substrate binds to the active site of enzyme (E+S).
Step 2: This induces about changes inwards enzymes together with then that the substrate is tightly leap amongst active site of enzyme to bird Enzyme-Substrate complex (ES).

Step 3: The active site breaks chemic bonds of the substrate to bird Enzyme-Product complex (EP).
Step 4: The enzyme releases the products together with the complimentary enzyme is make to bind to other molecules of the substrate (E+P).

Role of Enzyme (Concept of activation energy)

Activation unloosen energy is the minimum unloosen energy required to start a chemic reaction.

In an exothermic or an endothermic (energy requiring) reaction, the ‘S’ has to become through a much higher unloosen energy state. It is called transition nation energy. Therefore, activation unloosen energy is the departure betwixt average unloosen energy of substrate together with transition nation energy.

If the production (P) is at a lower unloosen energy bird than the substrate (S), the reaction is an exothermic reaction (spontaneous reaction). It requires no unloosen energy (by heating) inwards social club to bird the product. In a biochemical reaction, enzymes lower the activation energy. As a result, speed of the reaction increases.

Factors affecting enzyme activity

a) Temperature together with pH
Enzymes present highest activity at optimum temperature & pH. Activity declines below together with higher upwardly optimum value.

 

At depression temperature, enzyme temporarily inactive.
At high temperature, enzymes destroy because proteins are denatured past times heat.
b) Concentration of the substrate:

With the increment inwards substrate concentration, the velocity of enzyme activity rises at commencement together with reaches a maximum velocity (Vmax). This is non exceeded past times farther rising inwards concentration because enzyme molecules are fewer than the substrate molecules. I.e. No complimentary enzyme molecules to bind amongst additional substrate molecules.
c) Presence of  Inhibitor:
The binding of specific chemicals (inhibitor) shuts off the enzyme activity. This is called inhibition.

If the inhibitor closely similar to the substrate it is called competitive inhibitor. It competes amongst the substrate for the binding site of the enzyme. As a result, the substrate cannot bind together with the enzyme activity declines. 
E.g. Inhibition of succinic dehydrogenase past times malonate which is similar to the substrate succinate.
Competitive inhibitors are used to command bacterial pathogens.

Classification together with nomenclature of enzymes

1. Oxido-reductases / Dehydrogenases: They catalyze oxido-reduction betwixt 2 substrates.

S reduced + S’ oxidized → southward oxidized + S’ reduced

2. Transferases: They catalyze a transfer of a grouping (other than hydrogen).

S-G + S’ → S’-G + S

3. Hydrolases: They catalyze hydrolysis of ester, ether, peptide, glycosidic, C-C, C-halide or P-N bonds.
4. Lyases: They catalyze removal of groups past times mechanisms other than hydrolysis leaving double bonds.

X-C-C-Y → X-Y + C=C

5. Isomerases: They catalyze inter-conversion of optical geometric or positional isomers.
6. Ligases: They catalyze the linking together of 2 compounds. 
E.g. enzymes catalyzing joining of C-O, C-S, C-N, P-O etc.

Co-factors

Co-factors are non-protein constituents leap to the enzyme to brand the enzyme active.

The protein share of the enzyme is called Apo-enzyme. 

Co-factor + Apoenzyme (inactive) = Holoenzyme (Active)

Co-factors are three types:
A) Prosthetic group: These are organic co-factor that are tightly leap to apoenzyme.
E.g. In peroxidase and catalase, haem is prosthetic group.
B) Co-enzymes: These are likewise organic compounds which are loosely leap to apoenzyme. The essential constituent of many co-enzymes is vitamins. E.g. NAD together with NADP comprise niacin.

C) Metal ions: They bird co-ordination bonds amongst side chains at active site together with the same fourth dimension bird 1 or to a greater extent than co- ordination bonds amongst the substrate.
E.g. Zn is a co-factor for Carboxypeptidase.