Q. What is prosthetic group? Write a note on different prosthetic group found in an enzyme?

 Answer-

    A prosthetic group is a non-amino acid component integral to the structure of heteroproteins or conjugated proteins, closely associated with the apoprotein.

Role- Serves a crucial function by being involved in the protein's biological activity, often through direct participation in the protein's chemical reactions.

Binding: Tightly linked to the protein structure, differentiating from loosely attached coenzymes that may dissociate.

Prosthetic groups are non-polypeptide units that are tightly and permanently attached to enzymes, playing crucial roles in their catalytic activity. Here are some notable examples of prosthetic groups found in various enzymes:

Examples of Prosthetic Groups

Heme

Function: Involved in oxygen binding and electron transport.

Distribution: Found in hemoglobin, myoglobin, and various cytochromes, such as cytochrome c oxidase.

Flavin Adenine Dinucleotide (FAD)

Function: Acts as an electron carrier in redox reactions.

Distribution: Present in several enzymes, including flavoproteins and succinate dehydrogenase.

Flavin Mononucleotide (FMN)

Function: Also serves as an electron carrier in redox reactions.

Distribution: Found in NADH dehydrogenase and other flavoproteins.

Biotin

Function: Serves as a cofactor for carboxylation reactions.

Distribution: Present in biotin-dependent carboxylases, such as pyruvate carboxylase.

Pyridoxal Phosphate (PLP)

Function: Involved in transamination, decarboxylation, and deamination reactions.

Distribution: Found in aminotransferases and other enzymes that require amino acid metabolism.

Thiamine Pyrophosphate (TPP)

Function: Essential for the transfer of 2-carbon units.

Distribution: Found in enzymes like pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase.

Molybdopterin

Function: Involved in oxygenation reactions.

Distribution: Found in enzymes such as nitrate reductase.

Lipoic Acid

Function: Functions in redox reactions and as a cofactor for several enzyme complexes.

Distribution: Present in the pyruvate dehydrogenase complex.

Copper Ions

Function: Participate in redox reactions and electron transport.

Distribution: Found in cytochrome c oxidase and other copper-containing enzymes.

Iron-Sulfur Clusters

Function: Involved in electron transfer and redox reactions.

Distribution: Present in various enzymes, including aconitase and succinate dehydrogenase.

These prosthetic groups are integral to the structure and function of their respective enzymes, often facilitating crucial biochemical reactions within cells. Their tight binding distinguishes them from other types of cofactors, which may associate more loosely with enzymes.