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.
Those are very, very conservative calculations. Some numbers cited by various no-idle campaigns estimate that 10 minutes of idling uses about 0.1 gallon of fuel (for a small car). If you idle 10 minutes a day, it adds up to more than 35 gallons a year. And it only takes 10-15 seconds worth of fuel to restart the car. You can save real money just by shutting off the engine on rail-road crossings, at drive-throughs, on long street lights (not recommended for average person) etc.