It is a catecholamine. It is also known as adrenaline. It will increase the heart rate and other flight or fight responses.
An exposure to sarin or sarin like chemical will caused the sarcoplasmic reticulum to be continuously stimulated by the continual electrical signal. This will open the calcium channels and allows the calcium ions to bind continuously with troponin. Sarin is an organophosphorus chemical which is highly poisonous. It is used as a chemical weapon of destruction.
Enzymes lower activation energy through various means, including positioning substrates together in the proper orientation, applying torque on the substrates, providing the proper charge or pH microenvironment, and adding or removing functional groups on the substrates.