Enzymes

Factors Affecting Enzyme Action

• Enzymes are proteins sensitive to conditions affecting their tertiary structure due to bonds holding amino acids.
• Optimal temperature is crucial; low temperatures mean insufficient kinetic energy, resulting in fewer enzyme-substrate complexes and lower reaction rates.
• High temperatures lead to denaturation; an increase in kinetic energy breaks bonds, altering the active site shape, preventing substrate binding.

pH Levels

• Enzymes have specific optimal pH levels; deviations (too high or too low) lead to denaturation.
• High pH (excess hydrogen ions) and low pH (excess hydroxide ions) disrupt ionic and hydrogen bonds, altering the active site's shape.
• Amylase has an alkaline optimum, while proteases function best at acidic pH levels, reflecting their natural environments.

Substrate and Enzyme Concentration

• Low substrate concentrations limit reaction rates due to fewer substrate molecules available for enzyme collisions.
• Increasing substrate concentration improves reaction rates until enzymes become saturated, leading to a plateau where reaction rate stabilizes.
• Similar dynamics apply to enzyme concentration; low enzyme levels slow reactions due to limited active sites, while excess enzyme can lead to saturation of substrates.

Inhibitors

• Inhibitors decrease enzyme activity by binding to the enzyme, preventing substrate interactions.
• Competitive Inhibitors: Molecules resemble substrates, binding to the active site and preventing substrate binding. High substrate concentrations can outcompete the inhibitor.
• Non-Competitive Inhibitors: Bind to an allosteric site (not the active site), altering the structure of the enzyme and active site. This prevents substrate binding, even with increased substrate concentrations.

Graphing Enzyme Activity

• Competitive inhibitors produce a reaction rate lower than without inhibitors until high substrate levels are reached, where they can be outcompeted.
• Non-competitive inhibitors result in a lower maximum reaction rate that plateaus, regardless of substrate concentration due to alteration of the active site's shape.

Factors Affecting Enzyme Action

• Enzymes are proteins with a delicate tertiary structure, influenced by bonds between amino acids.
• Optimal temperature is essential; too low reduces kinetic energy, causing fewer enzyme-substrate complexes and slower reaction rates.
• Excessive heat can denature enzymes; increased kinetic energy disrupts bonds, changing the active site and preventing substrate binding.

pH Levels

• Each enzyme has an optimal pH; significant deviations can cause denaturation.
• High pH levels (more hydrogen ions) and low pH levels (more hydroxide ions) disrupt ionic and hydrogen bonds, altering the active site shape.
• Amylase functions best in alkaline conditions, while proteases are optimized for acidic environments, reflecting their roles in digestion.

Substrate and Enzyme Concentration

• Limited substrate concentrations lead to slower reaction rates due to fewer collisions with enzymes.
• Increasing substrate concentration enhances rates until enzyme saturation occurs, resulting in a maximum reaction rate.
• Similar trends apply to enzyme concentrations; low enzyme levels can slow reactions, while excess enzymes may cause substrate saturation.

Inhibitors

• Inhibitors impede enzyme activity by attaching to enzymes and blocking substrate interactions.
• Competitive Inhibitors: Mimic substrates and occupy the active site, reducing enzyme efficiency; can be outcompeted by high substrate concentrations.
• Non-Competitive Inhibitors: Attach to allosteric sites, altering enzyme structure and active site orientation; sustain low maximum reaction rates regardless of substrate levels.

Graphing Enzyme Activity

• Reaction rates affected by competitive inhibitors show initial reductions but can reach normal levels at high substrate concentrations.
• Non-competitive inhibitors always produce lower maximum reaction rates that flatten out, due to structural changes in the active site.

Importance of Enzymes

• Enzymes are essential catalysts in biological reactions, facilitating diverse processes in living organisms.
• ATP synthase exemplifies an important enzyme, showcasing the variety and critical role of enzymes in biochemistry.

Key Enzyme Functions

• Digestive enzymes play a vital role in breaking down essential biomolecules:
  • Amylase: Catalyzes the conversion of starch into smaller sugars, primarily active in the mouth.
  • Lipase: Operates in the small intestine, converting triglycerides into fatty acids and glycerol.
  • Pepsin: Functions in the stomach to cleave protein bonds, producing peptides.
  • Trypsin: Works in the small intestine, further breaking down peptides into smaller units.
  • Nucleases: Hydrolyze nucleic acids into nucleotides by cleaving phosphodiester bonds.

Broad Role of Enzymes

• Enzymes are prevalent throughout human body systems, including excretory, respiratory, and circulatory, aiding in breakdown or synthesis of substances.
• Present in all living organisms and some viruses, enzymes are fundamental to life and biological processes.

Cofactors and Coenzymes

• Cofactors: Typically inorganic elements (e.g., zinc, iron) that assist enzyme activity.
• Coenzymes: Organic molecules (e.g., vitamins) important for enzyme function; for instance, zinc is crucial for DNA polymerase in replication.

Enzyme Inhibition

• Enzyme inhibitors can be reversible or irreversible and classified as competitive or noncompetitive:
  • Competitive Inhibitors: Bind to the enzyme's active site, blocking substrate access.
  • Noncompetitive Inhibitors: Attach to allosteric sites, altering enzyme shape and effectiveness irrespective of substrate binding.

Feedback Inhibition

• Feedback inhibition is a regulatory mechanism in biochemical pathways, preventing excess production of substances.
• The final product can inhibit an early enzyme, exemplified by product D inhibiting enzyme 1 to maintain balanced levels.

Clinical Significance

• A deep understanding of enzymes is crucial for advancements in drug development and disease treatment.
• ACE Inhibitors: Medications that lower blood pressure by blocking the enzyme that converts angiotensin, mitigating harmful cardiovascular effects.
• Penicillin: An antibiotic that targets transpeptidase, inhibiting bacterial cell wall synthesis as a strategy for microbial treatment.

Conclusion

• Understanding enzyme function and mechanisms enhances insights into biological processes and therapeutic uses, fostering scientific curiosity and exploration.

Importance of Enzymes

• Enzymes are essential catalysts in biological reactions, facilitating diverse processes in living organisms.
• ATP synthase exemplifies an important enzyme, showcasing the variety and critical role of enzymes in biochemistry.

Key Enzyme Functions

• Digestive enzymes play a vital role in breaking down essential biomolecules:
  • Amylase: Catalyzes the conversion of starch into smaller sugars, primarily active in the mouth.
  • Lipase: Operates in the small intestine, converting triglycerides into fatty acids and glycerol.
  • Pepsin: Functions in the stomach to cleave protein bonds, producing peptides.
  • Trypsin: Works in the small intestine, further breaking down peptides into smaller units.
  • Nucleases: Hydrolyze nucleic acids into nucleotides by cleaving phosphodiester bonds.

Broad Role of Enzymes

• Enzymes are prevalent throughout human body systems, including excretory, respiratory, and circulatory, aiding in breakdown or synthesis of substances.
• Present in all living organisms and some viruses, enzymes are fundamental to life and biological processes.

Cofactors and Coenzymes

• Cofactors: Typically inorganic elements (e.g., zinc, iron) that assist enzyme activity.
• Coenzymes: Organic molecules (e.g., vitamins) important for enzyme function; for instance, zinc is crucial for DNA polymerase in replication.

Enzyme Inhibition

• Enzyme inhibitors can be reversible or irreversible and classified as competitive or noncompetitive:
  • Competitive Inhibitors: Bind to the enzyme's active site, blocking substrate access.
  • Noncompetitive Inhibitors: Attach to allosteric sites, altering enzyme shape and effectiveness irrespective of substrate binding.

Feedback Inhibition

• Feedback inhibition is a regulatory mechanism in biochemical pathways, preventing excess production of substances.
• The final product can inhibit an early enzyme, exemplified by product D inhibiting enzyme 1 to maintain balanced levels.

Clinical Significance

• A deep understanding of enzymes is crucial for advancements in drug development and disease treatment.
• ACE Inhibitors: Medications that lower blood pressure by blocking the enzyme that converts angiotensin, mitigating harmful cardiovascular effects.
• Penicillin: An antibiotic that targets transpeptidase, inhibiting bacterial cell wall synthesis as a strategy for microbial treatment.

Conclusion

• Understanding enzyme function and mechanisms enhances insights into biological processes and therapeutic uses, fostering scientific curiosity and exploration.

Proteins and Amino Acids

• Amino acids are monomers that combine to form polymers, which are proteins.
• Peptide bonds link amino acids through a condensation reaction, resulting in dipeptides and polypeptides.
• Each amino acid has a central carbon (alpha carbon), a hydrogen atom, a carboxyl group, an amine group, and a variable R group.
• Functional proteins may consist of one or multiple polypeptide chains.

Levels of Protein Structure

• Primary structure: Unique sequence of amino acids, crucial for protein properties and functions.
• Secondary structure: Folding of primary structure into alpha helices or beta pleated sheets, stabilized by hydrogen bonds.
• Tertiary structure: Three-dimensional shape formed by further folding, important for enzyme specificity, involving ionic bonds and disulfide bridges.
• Quaternary structure: Multiple polypeptide chains together, sometimes with non-protein groups like metal ions (e.g., iron in hemoglobin).

Protein Testing

• Biuret test identifies proteins; a purple precipitate indicates protein presence, while no color change indicates absence.

Enzymes

• Enzymes are proteins that catalyze reactions by lowering activation energy.
• The substrate binds to the enzyme's active site, forming an enzyme-substrate complex; the induced fit model explains shape-induced changes in the enzyme.

Enzyme Specificity and Activity

• Enzyme specificity is determined by the complementary shape of the substrate to the active site.
• Optimal temperature for enzyme activity is around 40°C; higher temperatures lead to denaturation due to disrupted hydrogen bonds.
• Most enzymes function best at a neutral pH (7); exceptions include pepsin, which thrives in acidic environments (pH 2).
• Increasing enzyme concentration boosts reaction rates until limited by substrate availability.
• Increasing substrate concentration also increases reaction rates until active sites are saturated.

Enzyme Inhibition

• Competitive inhibition occurs when an inhibitor and substrate compete for the active site; increased substrate concentration can alleviate this.
• Non-competitive inhibition happens when an inhibitor alters the active site's shape permanently; this effect cannot be reversed by increasing substrate concentration.

Carrier Proteins and Enzyme Inhibition

• Carrier proteins assist in transport across cell membranes.
• Reduced active site occupancy leads to fewer enzyme-substrate complexes.
• Cyanide inhibits cytochrome oxidase in the electron transport chain, preventing aerobic respiration.

Mechanism of Cyanide Poisoning

• Cyanide serves as a competitive inhibitor, blocking cytochrome oxidase's active site.
• Inhibition diminishes metabolic activity in affected cells.
• Antidotes can prevent cyanide binding, mitigating its toxic effects.

Experimental Investigations of Cyanide's Effects

• Scientists measure oxygen consumption in organs exposed to cyanide.
• Significant reductions in oxygen usage were noted, e.g., sheep liver from 2.7 to 2.5 and sheep kidney from 15.1 to 9.9.
• Kidney tissue shows a greater impact from cyanide (87% oxygen decrease) compared to liver (74%).

Data Analysis in Experimental Trials

• Group comparisons can be based on animal species or organ type.
• Potential comparisons include sheep liver vs. sheep kidney or rat liver vs. sheep liver.
• Highlighting trends is essential for data interpretation.

Oxygen Uptake and Percentage Change Calculations

• Percentage change is calculated by subtracting initial values from final values, dividing by the initial, then multiplying by 100.
• Example: Rat liver shows an 81% decrease in oxygen consumption between cyanide concentrations of 10^-4 and 10^-2 M.

Factors Affecting Enzyme Activity

• Important factors include pH, substrate concentration, and enzyme concentration.
• Maintaining control over these parameters is vital for accurate enzyme activity measurement.

Enzyme Activity Rate Calculation

• The rate of reaction is represented as the gradient of a linear graph.
• Example calculation: At 25°C, a change of 10 units in Y and 240 in X results in a reaction rate of 0.042 per second (units: cm³/s).

Comparing Enzyme Activity at Different Temperatures

• At 37°C, higher kinetic energy increases enzyme-substrate complex formation; reactions plateau when substrates are exhausted, indicating maximum efficiency.
• Comparison between reactions at 37°C and 25°C shows optimal conditions for enzymatic activity at 37°C.