Question

Why doesn't the cell just use adrenaline to activate the protein kinase enzyme? Or even more simply, why doesn't adrenaline itself be an enzyme? Doesn't this make things much more easier?Or in other words, why does natural selection choose to use the more complicated second messenger as opposed to one messenger only?

Answer 1

Adrenaline cannot directly activate the protein kinase enzyme as it is a hormone, not an enzyme. The activation of protein kinase requires the conversion of ATP to cyclic AMP (cAMP) by the enzyme adenylate cyclase. The second messenger system involving cAMP and protein kinase allows for precise control and regulation of cellular processes.

Step-by-step explanation:

Adrenaline cannot directly activate the protein kinase enzyme because it is a hormone and not an enzyme itself. The activation of protein kinase requires the conversion of ATP to cyclic AMP (cAMP), which is done by the enzyme adenylate cyclase. Adrenaline binds to the hormone receptor site on the cell membrane and activates adenylate cyclase, leading to the production of cAMP. This second messenger system involving cAMP and protein kinase allows for more precise control and regulation of cellular processes, as it can activate or inhibit different enzymes and reactions in the cell.