ENZYMES

Question 1

• It is a compound usually a protein, that acts as a catalyst for a biochemical reaction
• Appearance of these in the blood often indicates that there is tissue damage in an organ and that cellular contents are spilling out into the bloodstream

Answer 1

ENZYME

Question 2

Composed only of protein

Answer 2

Simple enzyme

Question 3

Has a non – protein part in addition to a protein part.

Answer 3

Conjugated Enzyme

Question 4

Protein of the conjugated enzyme

Answer 4

Apoenzyme

Question 5

Non – protein part of the conjugated enzyme

Answer 5

Cofactor

Question 6

active conjugated enzyme produced from an apo-enzyme and a cofactor

Answer 6

Holoenzyme

Question 7

serves as a cofactor in a conjugated enzyme

Answer 7

Coenzyme

Question 8

Reactant in an enzyme – catalyzed reaction

Answer 8

Substrate

Question 8

• Small part of an enzyme’s structure that is actually involved in catalysis.
• A three – dimensional entity formed by groups that come from different parts of the protein chains

Answer 8

Enzyme active site

Question 9

The intermediate reaction species that is formed when a substrate binds to the active site of an enzyme.

Answer 9

Enzyme– Substrate Complex

Question 10

• Active site in the enzyme has the fixed, rigid geometrical conformation.
• Substrate with a complementary geometry can be accommodated.

Answer 10

Lock – and – Key Model

Question 11

• Enzyme’s active site is not rigid and static.
• There’s a Constant change in shape
• Result of the enzyme’s flexibility; it adapts the incoming substrate.

Answer 11

Induced – Fit Model

Question 12

• Catalyze only one reaction
• Most restrictive of all specificities
• Catalase – enzyme with absolute specificity

Answer 12

Absolute Specificity

Question 13

• Act only on molecules that have a specific functional group, such a hydroxyl, amino or phosphate groups.
• Carboxyl-peptidase is group specific

Answer 13

Group Specificity

Question 14

• Act on the particular type of bond, irrespective to the rest of the molecular structure.
• Phosphatases hydrolyze phosphate – ester bonds in all types of phosphate esters
• Most general of the common species

Answer 14

Linkage Specificity

Question 15

• Act on a particular isomer

Answer 15

Stereochemical specificity

Question 15

Factors that affects enzyme activity

Answer 15

-Temperature
-pH
- Substrate Concentration
- Enzyme Concentration

Question 16

-Molecule that sufficiently resembles an enzyme substrate in shape and charge distribution
-Remains in changed as it binds to the enzymes’s active site.
-Can be reduced but increasing the concentration of the substrate

Answer 16

Reversible Competitive Inhibition

Question 16

Substance that slows or stops the normal catalytic function of an enzyme by binding to it.

Answer 16

Enzyme inhibitor

Question 17

-Molecules that decreases enzyme activity by binding to a site on an enzyme other than the active site.
-Presence of this causes a change in the structure of the enzyme sufficient to prevent the catalytic groups

Answer 17

Reversible Non-Competitive Inhibition

Question 18

*Molecule that inactivates enzyme by forming a strong covalent bond to an amino acid side–chain group
*Do not have structures similar to that of the enzyme’s normal substrate

Answer 18

Irreversible Inhibition

Question 19

1. Have Quaternary Structure; (2 or more protein chains).
2. Have 2 kinds of binding sites (for substrates and for regulators).
3. Active and regulatory binding sites are distinct from each other in both location and shape.
4. Binding of a molecule at the regulatory site causes changes in the overall three – dimensional structure of the enzyme, including structural changes at the active site.

Answer 19

Allosteric Enzyme

Question 20

• Increase enzyme activity
• The shape of the active site is changed such that it can more readily accept substrate.

Answer 20

Positive Regulator

Question 21

• Decrease enzyme activity
• Changes to the active site are such that substrate is less readily accepted.

Answer 21

Negative Regulator

Question 22

• A process in which activation or inhibition of the first reaction in a reaction sequence is controlled by a product of reaction sequence

Answer 22

Feedback Control

Question 23

• Catalyzes the breaking of peptide bonds that maintain the primary structure of protein.
• Generated in an inactive form and converted to active form when they are needed.

Answer 23

Proteolytic Enzymes

Question 23

• Inactive precursor of a proteolytic enzyme.

Answer 23

Zymogen