Enzymes Flashcards
Lock & key hypothesis
enzyme has a specific active site ( lock ) to which a complementary substrate ( key ) fits into exactly ; forming an enzyme substrate complex ; lowering activation energy ; reaction occurs faster ; more products are formed ; enzyme remains unchanged at the end of the reaction
Characteristics of enzymes
1) specialised proteins
2) speed up chemical reactions ; catalyst
3) remain chemically unchanged ; can be used over & over ; used in small amounts
4) catalyse reversible reactions in both directions
5) affected by temperature & pH
6) enzyme activity is maximum at optimum temperature & pH
7) denatured by heat, strong acid & strong alkali ; denaturation is irreversible
Effect of temperature on enzymes
- increasing temperature to optimum increases kinetic energy of both enzyme & substrate ; they move faster & collide more frequently ; more products are formed
- if temperature increases beyond optimum temperature, enzyme will be denatured and non-functional ; substrate will not bind to active site anymore ; no products formed
Effect of pH on enzymes
- when pH fluctuates above/ below optimum, enzyme activity decreases
- if pH increases beyond optimum, enzyme will be denatured and substrate will not fit into active site anymore.