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.
When it is cold, say 30-45 degrees. I turn the key and the car starts right up, it idles a little fast, from I suppose a choke of some kind. In 30 seconds or so the engine purrs. BUT, if I put the car in 1st gear and start to release the clutch the engine jerks and will stall if I don't rev the engine and take off slowly. It then takes about 3-5 minutes to warm up and run fine. Also, if I let the car idle for 5 or ten minutes before starting to drive, there is not hesitation.