Cofactors and Coenzymes

What is an intracellular ?

catalyst reaction within cells

Eg : respiration

What is extracellular

Enzyme catalyses reactions outdoes of cells

Eg : saprotrophoc digestion by bacteria / fungi OR amylose sliced by salivary glands/ intestinal epithelial cells

What is a catalase + usage ?

Intracellular enzyme found in all organisms, it’s exposed to O2.

It protect cells digesting hydrogen peroxide into hydrogen + water.

faster reacting enzyme , with a turnover of 6 million / sec , cuz of the toxicity of H2O2.

WBC uses to kill microbes when they ingest them

Where is catalase found ?

It’s found inside cells in vesicles called ‘ peroxisomes ‘

What is H2 O2 ?

H2O2 is a harmful by product of many metabolic reactions.

What is a cofactors + usage ?

A small , non protein molecule which bind to enzyme’s active site or the allosteric site to enable them to work.

Acts as co - substance, to bind to the substrate to form/ change the complementary shape for active site.

Some cofactors change the distribution of charge on the active site at substrate , making enzyme substrate bonds easier to form.

Extra info about cofactors

Prosthetic Groups

These are cofactors permanently- bond to enzyme ( bound by covent bond )

Eg : Hemoglobin has an iron ion permanently bound to each of its 4 polypeptide chains, to bind to O2

What is a coenzyme ?

A small, non protein mole- protein molecule that bind temporary to the active site.

This happens either at the same time , or just before the substrate binds.

Coenzymes are changed during the reaction and have to be replaced before they can be used again.

Allosteric Activation

a mechanism of enzyme regulation where an activator molecule binds to a specific site on the enzyme other than the active site called the allosteric site causing a conformational change in the enzyme's structure that increases the affinity of the active site for its substrate, thereby increasing the enzyme's activity.