ENZYME

Characteristics of enzymes

• Protein in nature.

• Biological catalysts. Speed up reactions without being changed or used up.

• Act on reversible reaction.

• Action of enzymes is specific

• Work best at a certain range of pH and temperature.

• Action of enzymes is affected by inhibitor

Characteristics of enzymes

Protein

A + BC

enzyme

SpecificitypH

Biological catalyst

substrate

enzyme

active site

substrate

Action of enzyme (Anabolic reaction)

enzyme

substrate

enzyme

product

enzyme-substrate complex

enzyme-product complex

Action of enzyme (catabolic reaction)

products

enzyme

enzyme-product complex

enzyme

substrate

enzyme-substrate complex

Lock and key hypothesis

Substrate

Enzyme

product

product

Lock and key hypothesis

SHAPES

DON’T

MATCH

Factors affecting enzyme actionSubstrate concentration

Max. RateR

ate

of r

eact

ion

Substrate conc.

Factors affecting enzyme actionSubstrate concentration

Factors affecting enzyme actionTemperature

Rat

e of

rea

ctio

n

Temperature（ OC）

0 10 20 30 40 50

Factors affecting enzyme actionTemperature

• Each enzyme works best at a particular temperature - _____________________.

• When temperature is lower than optimum temperature, activity of enzyme become ________. At low temperature, enzymes become _____________. They become _________________ when the temperature is raised.

lowerinactive

active again

optimum temperature

Factors affecting enzyme actionTemperature

• Above the optimum temperature, heat changes the _______ of enzymes and their _____________, __________ their activities.

• When temperature is too high (above 60oC), most enzymes are ____________, and lose they catalytic property permanently.

shapeactive sites decreases

denatured

Factors affecting enzyme actionpH

Rat

e of

rea

ctio

n

pH

Application of Enzymes

Washing Powder

SCIENCE SECTION CURRICULUM DEVELOPMENT INSTITUTEEDUCATION DEPARTMENT