Many enzymes consist of a protein and a non-protein (called the cofactor). The proteins in enzymes are usually globular. The intra- and intermolecular bonds that hold proteins in their secondary and tertiary structures are disrupted by changes in temperature and pH. This affects shapes and so the catalytic activity of an enzyme is pH and temperature sensitive.
Everyday in the U.S. millions of cars and trucks idle needlessly, sometimes for hours. You may not be able to avoid keeping your engine running when youâre stopped at a traffic signal or stuck in slow-moving traffic. But other times idling is unnecessary. An idling car can release as much pollution as a moving car.
Both the EPA and Energy.gov say a car should not idle for more than 30 seconds at a time. Not only is it more environmentally friendly, but also cost-effective. Idling for 30 seconds actually uses more fuel than restarting the car. In major cities, officials restrict how long the average driver can idle his/her car. Minneapolis, for example, limits the length of idling to three minutes, barring some exceptions (when it is below zero degrees Fahrenheit or higher than 90, idling is permitted up to 15 minutes an hour).