Enzyme Nomenclature Quiz

Structural Similarity

• Analogs are structurally similar compounds that have the same functional groups

Specificity of Enzymes

• Linkage specificity refers to the enzyme's ability to catalyze a reaction at a specific bond or linkage in a substrate molecule.

Temperature and Enzyme Activity

• Higher temperatures increase enzyme activity by increasing molecular motion and collisions between enzymes and substrates, leading to faster reaction rates.
• The optimum temperature for human enzymes is 37 °C (98.6 °F)

pH and Enzyme Activity

• Drastic changes in pH can affect enzyme activity by altering their three-dimensional structure (conformation), damaging their active sites, and reducing their efficiency.

Substrate Concentration and Enzyme Activity

• At a constant enzyme concentration, increasing substrate concentration increases enzyme activity until a saturation point is reached, where all active sites are occupied by substrate.

Types of Enzyme Specificity

• Absolute specificity refers to when an enzyme can catalyze a particular reaction for only one substrate.

Models for Enzyme-Substrate Binding

• The lock-and-key model proposes that an enzyme has a predetermined shape for the active site that perfectly complements the substrate.
• Induced fit model states that the active site is flexible and adjusts its shape in response to substrate binding.

Forces Involved in Substrate Binding

• Noncovalent interactions, including hydrogen bonds, ionic interactions, van der Waals forces, and hydrophobic interactions, play a role in determining substrate binding to enzymes.

Enzyme-Substrate Intermediate

• The formation of an enzyme-substrate complex (ES complex) represents an intermediate reaction species formed when a substrate binds with the enzyme's active site.

Inductive Fit and Active Site Flexibility

• Inductive fit allows a slight change in the active site's shape to accommodate a substrate.

Stereochemical Specificity

• Stereochemical specificity occurs in enzymes that can distinguish between L-amino acids and D-amino acids, for example, L-amino acid oxidase catalyzes the oxidation of L-amino acids but not D-amino acids.

Oxidoreductase Enzymes

• Oxidoreductases catalyze oxidation-reduction reactions, which involve the transfer of electrons between molecules, with one molecule being oxidized and the other reduced.

Naming Digestive Enzymes

• The suffix "-ase" is commonly found in the names of some digestive enzymes, e.g., peptidase, lipase, and amylase.

Hydrolase Enzyme Function

• Hydrolases catalyze the hydrolysis reaction, cleaving chemical bonds by adding a water molecule.

Coenzymes in Oxidoreductases

• Nicotinamide adenine dinucleotide (NAD+) is a common coenzyme required for oxidoreductase enzymes.

Function of "-ase" Suffix

• Enzymes with the suffix "-ase" primarily function as biological catalysts, speeding up chemical reactions in living organisms without changing the equilibrium of the reaction.

Oxidation and Reduction in Oxidoreductases

• Oxidation and reduction reactions are coupled processes in oxidoreductases, where one molecule loses electrons (oxidation) while another gains electrons (reduction).

Vitamins: Structure and Function

• B Vitamins function as coenzymes in various metabolic reactions.
• Vitamin K is synthesized by bacteria in the colon and is also obtained from dietary sources (approximately 50%).
• Vitamin A plays a crucial role in vision by converting retinal to rhodopsin, a light-sensitive pigment.
• Vitamin E has a hydrocarbon-like structure with fewer functional groups and acts as an antioxidant.

Covalent Modification of Enzymes

• Covalent modification is a process in which enzyme activity is altered by covalently modifying the enzyme's structure.

Antibiotics and Enzyme Inhibition

• Penicillin belongs to a family of antibiotics that inhibit specific enzymes essential to the life processes of bacteria.

Phosphorylation

• Phosphorylation, the addition and removal of a phosphate group, is the most common covalent modification of enzymes.
• Phosphatases are enzymes that catalyze the removal of a phosphate group in covalent modification.

Premature Pepsin Production

• Premature production of pepsin in the stomach can lead to gastric ulcers, as it starts to digest the stomach lining.

Zymogens

• Zymogens are inactive precursors of enzymes, also known as proenzymes.