Graduate
  1. Physical Chemistry  1.1. Thermodynamics  1.1.1. Laws of Thermodynamics  1.1.2. Enthalpy and heat capacity  1.1.3. Entropy and free energy  1.1.4. Phase Equilibrium  1.1.5. Statistical thermodynamics  1.1.6. Thermodynamic cycle  1.1.7. Fugacity and activity  1.2. Quantum Chemistry  1.2.1. Principles of quantum mechanics  1.2.2. Schrödinger Equation  1.2.3. Particle in a box  1.2.4. Operators and eigenvalues  1.2.5. Atomic orbitals  1.2.6. Molecular orbital theory  1.2.7. Perturbation theory  1.2.8. Valence bond theory  1.2.9. Hybridization and chemical bonding  1.3. Chemical kinetics  1.3.1. Rate laws and reaction mechanisms  1.3.2. Collision theory  1.3.3. Transition state theory  1.3.4. Enzyme Kinetics  1.3.5. Chain Reactions and Polymerization  1.3.6. Photochemical reactions  1.4. Statistical mechanics  1.4.1. Partitioning functions  1.4.2. Molecular distribution functions  1.4.3. Boltzmann Distribution  1.4.4. Bose–Einstein and Fermi–Dirac statistics  1.5. Spectroscopy  1.5.1. Rotational Spectroscopy  1.5.2. Vibrational Spectroscopy  1.5.3. Electronic Spectroscopy  1.5.4. Nuclear magnetic resonance spectroscopy  1.5.5. Mass Spectrometry  1.5.6. Raman Spectroscopy  1.5.7. Electron paramagnetic resonance spectroscopy  1.6. Surface and colloidal chemistry  1.6.1. Absorption isotherm  1.6.2. Surface tension and wetting  1.6.3. Colloidal Stability  1.6.4. Catalysis  1.6.5. Emulsions and micelles  1.7. Electrochemistry  1.7.1. Nernst equation  1.7.2. Electrochemical cells  1.7.3. Conductivity and mobility  1.7.4. War  1.7.5. Fuel cells  1.7.6. Electrolysis
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic reactions  2.2. Spectroscopy and structural determination  2.2.1. UV-Vis Spectroscopy  2.2.2. IR Spectroscopy  2.2.3. NMR Spectroscopy  2.2.4. Mass Spectrometry  2.2.5. X-ray crystallography  2.3. Stereoscopic  2.3.1. Chirality and optical activity  2.3.2. Structural analysis  2.3.3. Geometrical isomerism  2.3.4. Dynamic Stereochemistry  2.4. Organometallic Chemistry  2.4.1. Organolithium and organomagnesium reagents  2.4.2. Palladium-catalyzed cross-coupling reactions  2.4.3. Transition Metal Complexes  2.4.4. Metal–carbon bond  2.5. Polymer chemistry  2.5.1. Polymerization mechanism  2.5.2. Polymer Characteristics  2.5.3. Biodegradable Polymer  2.5.4. Conducting polymer  2.5.5. Supramolecular polymers  2.6. Medicinal chemistry  2.6.1. Drug design and development  2.6.2. Pharmacokinetics and pharmacodynamics  2.6.3. Structure-activity relationships  2.6.4. Molecular docking and drug screening
  3. Inorganic chemistry  3.1. Coordination chemistry  3.1.1. Crystal field theory  3.1.2. Ligand field theory  3.1.3. Spectrochemical Series  3.1.4. Chelation and stability  3.2. Organometallic Chemistry  3.2.1. Metal Carbonyls  3.2.2. Catalysis by organometallic complexes  3.2.3. Metallocenes  3.3. Bio-inorganic chemistry  3.3.1. Metalloproteins and enzymes  3.3.2. The role of metals in biological systems  3.3.3. Metal ion transport and storage  3.4. Solid state chemistry  3.4.1. Crystal Structures  3.4.2. Band theory of solids  3.4.3. Superconductors  3.4.4. Defects in the crystal  3.5. Lanthanides and Actinides  3.5.1. Electronic configuration in lanthanides and actinides  3.5.2. Coordination chemistry of the lanthanides  3.5.3. Magnetic Properties of Lanthanides
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.2. Spectroscopic Techniques  4.2.1. Atomic absorption spectroscopy  4.2.2. X-ray diffraction  4.2.3. Inductively coupled plasma spectroscopy  4.3. Electroanalytical methods  4.3.1. Potentiometry  4.3.2. Voltammetry  4.3.3. Colometry  4.4. Mass Spectrometry  4.4.1. Ionization Technique  4.4.2. Fragmentation Pattern  4.5. Chemometrics  4.5.1. Multidisciplinary analysis  4.5.2. Machine Learning in Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.1.1. Force fields and energy minimization  5.1.2. Monte Carlo simulation in molecular dynamics simulations  5.2. Quantum chemical methods  5.2.1. Hartree–Fock theory  5.2.2. Density functional theory  5.2.3. Semi-empirical methods  5.3. Computational drug design  5.3.1. Molecular Docking  5.3.2. QSAR Modeling  5.3.3. Virtual Screening
  6. Biochemistry  6.1. Enzyme Kinetics  6.1.1. Michaelis-Menten kinetics  6.1.2. Inhibition mechanism  6.2. Metabolism and Bioenergetics  6.2.1. Glycolysis  6.2.2. Citric acid cycle  6.2.3. Electron transport chain  6.3. molecular Biology  6.3.1. DNA replication and repair  6.3.2. Protein synthesis  6.3.3. Gene Regulation  6.4. Structural Biochemistry  6.4.1. Protein Folding  6.4.2. Membrane Biophysics
  7. Environmental Chemistry  7.1. Atmospheric Chemistry  7.1.1. Greenhouse gases  7.1.2. Ozone depletion  7.1.3. Air pollutants and smoke  7.2. Water Chemistry  7.2.1. pH and water hardness  7.2.2. Wastewater treatment  7.2.3. Aquatic Chemistry  7.3. Soil Chemistry  7.3.1. Heavy metal contamination  7.3.2. Soil pH and Buffering  7.3.3. Nutrient cycling  7.4. Toxicology and Chemical Safety  7.4.1. Toxicokinetics  7.4.2. Risk Assessment in Toxicology and Chemical Safety in Environmental Chemistry  7.4.3. Effects of pollutants on the environment

Graduate → Biochemistry ↓


Enzyme Kinetics


Enzyme kinetics is the study of the rates of enzyme-catalyzed reactions. This branch of biochemistry provides information about how enzymes work, how they can be affected by various factors, and their role in biological systems. Understanding enzyme kinetics is important for applications in drug development, biotechnology, and disease diagnosis and treatment.

Basics of enzyme action

Enzymes are biological catalysts that speed up chemical reactions without being consumed in the process. They do this by lowering the activation energy needed for the reaction to proceed. Enzymes are specific for substrates, the molecules they act on, and this specificity is determined by the enzyme's unique three-dimensional structure.

Enzyme-substrate complex

Enzyme action begins when a substrate binds to the enzyme's active site, forming an enzyme-substrate complex. The active site is a specific region on the enzyme where the substrate fits, usually through non-covalent interactions such as hydrogen bonds, ionic bonds, and hydrophobic interactions.

Enzymes Substrate Binding

Example: catalase reaction

An example of enzyme action is the breakdown of hydrogen peroxide (H2O2) by catalase. The reaction is as follows:

2 H 2 O 2 → 2 H 2 O + O 2

Catalase accelerates the breakdown of hydrogen peroxide (a potentially harmful byproduct of cellular metabolism) into water and oxygen.

Michaelis-Menten kinetics

The Michaelis-Menten model describes the rate of enzymatic reactions by relating the reaction rate to the substrate concentration. It is based on the formation of an enzyme-substrate complex and its subsequent conversion to product.

The main features of the Michaelis-Menten equation are:

v = (V max [S]) / (K m + [S])
  • v is the initial reaction rate.
  • [S] is the substrate concentration.
  • V max is the maximum reaction rate.
  • K m is the Michaelis constant, a measure of substrate affinity.

K m represents the substrate concentration at which the reaction rate is half of V max. A low K m indicates high affinity between the enzyme and the substrate, meaning that the enzyme is effective at converting the substrate to product even at low substrate concentrations.

Visual representation of the Michaelis-Menten curve

[S] v Michaelis–Menten curve

Factors affecting enzyme kinetics

Many factors can affect the rate of enzyme-catalyzed reactions, including substrate concentration, enzyme concentration, temperature, pH, and the presence of inhibitors or activators.

Substrate concentrations

As the substrate concentration increases, the reaction rate increases linearly until the enzyme becomes saturated. Beyond this point, any additional substrate will not affect the rate. This plateau at high substrate concentrations corresponds to V max.

Enzyme concentrations

The reaction rate is directly proportional to the enzyme concentration. Doubling the enzyme concentration doubles the reaction rate, provided the substrate is in excess.

Temperature

Enzymes have an optimum temperature range where their activity is highest. Too low or too high temperatures can cause their activity to decrease. High temperatures can cause enzyme denaturation.

pH

Each enzyme has an optimum pH range. Deviation from this pH range can result in decreased enzyme activity and denaturation.

Inhibitors and activators

Inhibitors are molecules that reduce enzyme activity. They can be competitive, non-competitive or non-competitive.

  • Competitive inhibitors: bind to the active site and prevent substrate binding. This type of inhibition can be overcome by increasing the substrate concentration.
  • Non-competitive inhibitors: bind to a site other than the active site and reduce enzyme activity regardless of substrate concentration.
  • Noncompetitive inhibitors: bind to the enzyme-substrate complex and prevent the release of the product.

Catalysts enhance the activity of an enzyme by increasing its binding to the substrate or by increasing the catalytic efficiency of the enzyme.

Lineweaver–Burk plot

The Lineweaver-Burk plot is a double-reciprocal plot used to determine the enzyme kinetics parameters K m and V max. It is a linear transformation of the Michaelis-Menten equation:

1/v = (K m /V max )(1/[S]) + 1/V max

In this plot:

  • The Y-intercept gives 1/V max.
  • The x-intercept gives -1/K m.
  • The slope of the line is K m /V max.

Visual representation of the Lineweaver-Burk plot

1/[S] 1/V Lineweaver–Burke Line

Conclusion

Enzyme kinetics is a fundamental aspect of understanding how enzymes function and regulate biological processes. By analyzing the factors that affect enzyme activity and using models such as Michaelis-Menten and Lineweaver-Burk plots, scientists can determine key parameters that describe enzyme behavior. With these insights, applications in medicine, industry, and research become more efficient and targeted.


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Enzyme Kinetics

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