This causes the formation of more enzyme-substrate complexes, leading to an increase in enzyme activity.
This means the active site loses its important shape and can no longer form enzyme-substrate complexes, leading to a decrease in enzyme activity.
Denaturation is a permanent change.
Some enzymes (e.g. in biological washing powders) are thermostable, meaning they can work at a wide range of temperatures.
This allows biological washing powder to be used at low temperatures that saves energy and money.