Enzyme Function Factors Flashcards

Factors Affecting Enzyme Function

• Key factors include enzyme concentration, substrate concentration, temperature, pH, salinity, activators, inhibitors, allosteric regulation, metabolic pathways, and overall efficiency.

Enzyme Concentration

• Increasing enzyme concentration enhances the reaction rate until substrate becomes limiting, leading to saturation where not all enzyme active sites can bind to substrates.

Substrate Concentration

• Higher substrate concentration accelerates the reaction rate, but it levels off once all enzymes are saturated, meaning every active site is occupied.

Temperature Effects

• Elevated temperature increases molecular energy, which can disrupt weak bonds, potentially causing denaturation and loss of the enzyme's 3D structure.

Cold Temperature Effects

• Cold temperatures reduce molecular movement, leading to fewer collisions between enzymes and substrates, thus slowing reaction rates.

Endotherms and Ectotherms

• Endotherms are warm-blooded animals that thrive at above-average temperatures; ectotherms are cold-blooded animals that prefer lower temperatures.

pH Influence

• Changes in pH introduce or remove hydrogen ions, disrupting bonds and 3D shapes, potentially leading to denaturation of proteins. Most human enzymes prefer a pH of 6-8.
• Pepsin, an enzyme in the stomach, functions optimally at a pH of 2-3, while trypsin, found in the small intestine, prefers pH 8.

Salinity

• Salinity refers to salt concentration, which affects enzyme function similarly to pH by adding or removing ions, disrupting bonds, and impacting enzyme shape.

Enzyme Activity and the Dead Sea

• Extreme salinity in the Dead Sea hinders enzyme functionality, rendering it "dead" in terms of biological activity.

Activators and Cofactors

• Activators support enzyme activity and include cofactors (small, inorganic compounds like Mg, K, Ca) and coenzymes (organic molecules like NAD and FAD) that bind near the active site.

Inhibitors

• Inhibitors are molecules that reduce enzyme activity, classified into competitive and noncompetitive inhibitors, and play a role in allosteric regulation.

Competitive Inhibition

• Competitive inhibitors compete with substrates for the active site. Examples include penicillin, which inhibits bacterial cell wall formation, and disulfiram, which disrupts alcohol breakdown.

Overcoming Competitive Inhibition

• Increasing substrate concentration can outcompete competitive inhibitors, thus maintaining enzyme activity.

Noncompetitive Inhibition

• Noncompetitive inhibitors bind to an alternative site, altering enzyme shape and function without competing for the active site. Examples include certain anticancer drugs and cyanide.

Irreversible Inhibition

• Irreversible inhibitors permanently bind to enzymes, which can occur through competitive or allosteric means, leading to permanent loss of enzyme function.

Allosteric Inhibition

• Allosteric inhibitors bind to sites other than the active site, causing conformational changes that render the active site nonfunctional.

Feedback Inhibition

• Feedback inhibition is a regulatory mechanism where the end product of a metabolic pathway inhibits an earlier enzyme to prevent overproduction, maintaining efficiency.

Allosteric Regulation

• Involves conformational changes in enzymes induced by regulatory molecules. Activators ensure enzymes remain in active forms.

Metabolic Pathways

• Chemical reactions of life are organized in pathways to enhance efficiency, allowing control over sequential reactions and preventing unnecessary accumulation of products.