Answer:
enzymes loose their form in both unsuitable ph and temprature.
Explanation:
at very high tempratures enzyme molecules denatures due to high speed movements, at low tempratures enzymes works too slow to be useful enough.
low ph solotions contain lot of H+ and high ph solutions have few H+ , and the number of these H+ ions have polar effects on enzymes. some Enzymes like pepsin works perfect in acidic environment ( ph=2) while others might work at high ph or average ph( like Trypsin works well at ph=7).