Enzyme Active Sites & Thermal Stability — NEET Biology
📚 Practice ConceptOne such pocket is the 'active site'. An active site of an enzyme is a crevice or pocket into which the substrate fits. Thus enzymes, through their active site, catalyse reactions at a high rate. Enzyme catalysts differ from inorganic catalysts in many ways, but one major difference needs mention. Inorganic catalysts work efficiently at high temperatures and high pressures, while enzymes get damaged at high temperatures (say above 40°C). However, enzymes isolated from organisms who normally live under extremely high temperatures (e.g., hot vents and sulphur springs), are stable and retain their catalytic power even at high temperatures (upto 80°-90°C). Thermal stability is thus an important quality of such enzymes isolated from thermophilic organisms.
Which of the above statements are NOT correct? S1: Enzymes from thermophilic organisms typically lose their catalytic power at temperatures above 40°C, similar to most human enzymes. S2: Low temperatures temporarily inactivate enzymes, while high temperatures cause irreversible denaturation of their protein structure. S3: Each enzyme exhibits its highest activity over a broad range of temperature and pH, making them versatile across varying physiological conditions. S4: Beyond the optimum substrate concentration, the velocity of an enzyme-catalyzed reaction declines rapidly due to substrate inhibition. S5: The tertiary structure of an enzyme is unaffected by changes in pH and temperature, ensuring constant activity.
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