Thursday, 18 September 2014

Why are kinases called kinases?

Kinases are one of the biggest and most important classes of enzymes (i.e. protein with catalytic activity) in biology. You can always recognise an enzyme because of the suffix “-ase”. What comes before the -ase then indicates the nature of the enzymatic activity.

The major classes of enzyme have names that give a good clue as to the general nature of this activity. Oxidoreductases, for example, catalyse oxidation-reduction (“redox”) reactions. Transferases transfer chemical groups from one molecule to another. Kinases are transferases: they transfer a phosphate group from one organic molecule (usually ATP, the cell’s primary energy carrier) to another (a protein, lipid or carbohydrate). And this is actually the origin of the kin- part of the name: from the Greek kinein “to move”.

For those wondering, there is also such as thing as a Phosphorylase but this does something subtly different; whereas a kinase transfers organic phosphate groups (i.e. phosphates attached to carbon-based biomolecules), a phosphorylase transfers inorganic phosphate groups (i.e. phosphate+hydrogen) to acceptor biomolecules.

But why -ase? This stems from the ending of diastase, the first enzyme ever discovered. According to Wikipedia:

“The name “diastase” comes from the Greek word διάστασις (diastasis) (a parting, a separation) because when beer mash is heated, the enzyme causes the starch in the barley seed to transform quickly into soluble sugars and hence the husk to separate from the rest of the seed.”

So there you have it. A kinase is an early example of an enzyme that moves something from one molecule to another, hence a name that literally means “an enzyme to move”.