What are Biochemical cofactors

TOPIC # 4 

COFACTORS:

       Cofactors are atoms,group of atoms and molecules that join with enzymes alter their shape and making them functional.

It is also called as non protein part of and enzyme.

It act as on/off key of enzyme.

It is also called as  functional group of an enzyme.

Enzymes are totally proein in nature and their function is to speed up of a reaction however some enzymes requires non protein molecules for their function these non protein molecules are termed as  Cofactors.

Those enzymes which work only in presence of cofactor called as Holoenzyme and if cofactor is not present so that enzyme remains in inactive form called as apoenzyme.

    Enzyme + cofactor= Holo enzyme (functional)

    Enzyme without cofactor= Apoenzyme(non functional)

FOR EXAMPLE:

    The perfect example of this type of enzyme is Pepsin.

Pepsin is released by stomach wall in inactive form called as pepsinogen.

In inactive form it has one more polypeptide fragment which dont allow the substrate to find with active site .

So when that pepsinogen exposed to HCL the additional polypeptide fragment is removed as a result inactive pepsionogen convert into active enzyme pepsin.

TYPES OF COFACTORS:

Now we will study various type of  Cofactors;

1-INORGANIC COFACTORS:

    These type of cofactors are mostly inorganic metallic ions like cu++,Zn++,Mg++ etc.

A-ACTIVATOR:

          The type of co factor which is actually metallic ions attach to enzyme temporarily and activate enzyme called as Activators.

It is also called as Detacheable cofactors.

     GLUCOSE + ATP     (HEXOKINASE + Mg+2(Activator)   =  Glucose 6 phosphate + ADP

2-ORGANIC COFACTORS:

   Type of cofactors which are non protein organic molecules .

A-PROSTHETIC GROUP:

    The organic molecules which covalently bind to enzyme on permanent basis and doesnot detached after the completion of reaction.

      An iron containing porphyrin ring in heamoglobin attached to some enzymes like cytochromes is the example of prosthetic group.

B-COENZYMES:

           The type of organic cofactors mostly derivatives of vitamins and minerals called as Coenzymes like NAD+,ATP,FAD+ etc.

The absence of these cofactors lead to vitamin and mineral defeciency diseases like lack of vitamin B leads to beriberi disease.

      Ethyl alcohol     +   Alcohol Dehydrogenase + NAD+(COENZYME)   = ACETALDEHYDE +NADH2.

IMPORTANT MCQS IN THIS TOPIC:

1-The group of molecules that make enzyme functional called as:

Answer:  COFACTORS

2-The functional group of enzyme is called as:

Answer: COFACTORS

3-The pepsinogen is called as _enzyme:

Answer: APOENZYME(INACTIVE)

4-ATP is the example of _cofactor:

Answer: ORGANIC COFACTOR

5-The detacheable cofactors are called as:

Answer: ACTIVATOR

6-The fumctional enzyme is called as:

Answer: HOLOENZYME

7-The _cofactor attach to enzyme on permanent basis:

Answer: PROSTHETIC GROUP

8-Lack of which type of cofactor result in defeciency diseases:

Answer: COENZYMES

9-Which type of cofactors are detacheable:

Answer: ACTIVATOR(INORGANIC) AND COENZYME(ORGANIC)

10-Mg+2 is _type of cofactor:

Answer: INORGANIC 

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