Chapter 13 - Enzymes

Enzyme

Biological protein catalyst that speeds up metabolic reactions without being used up.

Catalyst

Substance that alters the rate of a chemical reaction without being consumed.

Substrate

Specific molecule upon which an enzyme acts.

Product

New substance formed at the end of an enzyme-controlled reaction.

Active site

Specific 3D folded region of an enzyme where the substrate binds.

Enzyme specificity

Ability of an enzyme to react with only one specific substrate due to active site shape.

Induced Fit Model

Theory that the active site changes shape slightly to fit the substrate snugly.

Enzyme-substrate complex

Temporary structure formed when substrate binds to the enzyme active site.

Optimum temperature

Temperature at which an enzyme works fastest (37°C in humans).

Optimum pH

Specific pH at which an enzyme has maximum activity (e.g. pepsin pH 2, amylase pH 7).

Denaturation

Permanent loss of an enzyme's 3D shape and function caused by high heat or extreme pH.

Bioprocessing

Use of enzyme-controlled reactions to produce useful commercial products.

Bioreactor

Vessel in which living cells or enzymes carry out bioprocessing under controlled conditions.

Immobilized enzymes

Enzymes trapped in an inert material so they can be easily recovered and reused.

Sodium alginate

Gel substance used to trap enzymes into beads during immobilization.

Calcium chloride

Solution used to harden sodium alginate drops into insoluble enzyme beads.

Advantages of immobilized enzymes

Reusable, easy to separate from product, and more stable at higher temperatures.

Catalase

Enzyme found in celery or liver that breaks down hydrogen peroxide into water and oxygen.

Mandatory Exp: Effect of pH on enzyme

Vary pH buffers with catalase and hydrogen peroxide; measure foam height per minute.

Mandatory Exp: Effect of temp on enzyme

Place catalase and hydrogen peroxide in different water baths; measure foam height.

Mandatory Exp: Heat denaturation of enzyme

Boil catalase before adding hydrogen peroxide; no foam forms because enzyme denatured.

Mandatory Exp: Immobilizing enzymes

Mix yeast (sucrase) with sodium alginate, drop into calcium chloride, and convert sucrose to glucose.