PHD
  1. Inorganic chemistry  1.1. Coordination chemistry  1.1.1. Ligand field theory  1.1.2. Crystal field theory  1.1.3. Molecular Orbital Theory for Coordination Compounds  1.1.4. Stability of Coordination Compounds  1.1.5. Electronic spectra of coordination compounds  1.1.6. Isomerism in Coordination Compounds  1.1.7. Kinetics and mechanism of coordination reactions  1.2. Organometallic Chemistry  1.2.1. Metal Carbonyls  1.2.2. Metal alkyl and aryl  1.2.3. Fischer and Schrock carbonaceans  1.2.4. Oxidative Addition and Reductive Elimination  1.2.5. Metal Hydrides  1.2.6. Catalysis by organometallic compounds  1.2.7. Metallocenes and Sandwich Complexes  1.2.8. CH activation  1.3. Solid state chemistry  1.3.1. Crystal structures and lattices  1.3.2. Band theory and electrical properties  1.3.3. Defects in the crystal  1.3.4. Synthesis of solid state materials  1.3.5. Magnetic and optical properties of solids  1.3.6. Superconductivity  1.3.7. Solid state ionics  1.4. Bio-inorganic chemistry  1.4.1. Metalloproteins and enzymes  1.4.2. Metal ion transport and storage  1.4.3. The role of metals in medicine  1.4.4. Bioinspired catalysis  1.4.5. Metal–DNA interactions  1.4.6. Metal Complexes in Medical Science  1.5. Lanthanides and Actinides  1.5.1. Electronic configuration and oxidation states in lanthanides and actinides  1.5.2. Spectral and Magnetic Properties in Lanthanides and Actinides  1.5.3. Separation and Extraction of Lanthanides and Actinides  1.5.4. Coordination chemistry of f-block elements  1.6. Main Group Chemistry  1.6.1. Chemistry of boron compounds  1.6.2. Chemistry of Silicon and Germanium Compounds  1.6.3. Chemistry of Phosphorus and Sulfur Compounds  1.6.4. Organosilicon chemistry  1.6.5. Noble Gas Chemistry
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition and substitution reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic Reactions  2.1.7. Photochemical reactions  2.2. Stereoscopic  2.2.1. Chirality and optical activity  2.2.2. Structural analysis  2.2.3. Stereoelectronic effects  2.2.4. Asymmetric synthesis  2.2.5. Dynamic Stereochemistry  2.3. Organometallic Chemistry in Organic Synthesis  2.3.1. Organolithium and organomagnesium reagents  2.3.2. Transition metal catalyzed coupling reactions  2.3.3. Palladium-catalyzed reactions  2.3.4. Olefin Metathesis  2.3.5. Gold and silver catalysis  2.4. Natural products chemistry  2.4.1. Alkaloids and terpenoids  2.4.2. Steroids and Flavonoids  2.4.3. Total synthesis of natural products  2.4.4. Biosynthesis of natural products  2.5. Supramolecular Chemistry  2.5.1. Host-Guest Chemistry  2.5.2. Self-assembly and molecular recognition  2.5.3. Supramolecular Catalysis  2.5.4. Molecular Machines
  3. Physical Chemistry  3.1. Thermodynamics  3.1.1. Laws of Thermodynamics  3.1.2. Chemical Potential and Equilibrium  3.1.3. Statistical thermodynamics  3.1.4. Non-equilibrium thermodynamics  3.2. Quantum Chemistry  3.2.1. Schrödinger equation and its applications  3.2.2. Molecular orbital theory  3.2.3. Density functional theory  3.2.4. Post-Hartree–Fock methods  3.3. Chemical kinetics  3.3.1. Reaction rate theory  3.3.2. Mechanism and rate laws  3.3.3. Catalysis and enzyme kinetics  3.3.4. Reaction dynamics  3.4. Spectroscopy and molecular structure  3.4.1. Infrared Spectroscopy  3.4.2. UV-visible spectroscopy  3.4.3. Nuclear Magnetic Resonance Spectroscopy  3.4.4. Mass Spectrometry  3.4.5. Raman Spectroscopy  3.5. Surface and Colloid Chemistry  3.5.1. Absorption and Catalysis  3.5.2. Surfactants and micelles  3.5.3. Colloidal Stability  3.5.4. Nanomaterials and Interfaces
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.1.4. Ion Chromatography  4.2. Electroanalytical techniques  4.2.1. Voltammetry and Polarography  4.2.2. Conductometry and potentiometry  4.2.3. Colometry  4.3. Spectroscopic Methods  4.3.1. Atomic absorption spectroscopy  4.3.2. Fluorescence Spectroscopy  4.3.3. X-ray diffraction  4.3.4. Electron paramagnetic resonance spectroscopy  4.4. Chemometrics  4.4.1. Data processing and statistical methods  4.4.2. Multidisciplinary analysis  4.4.3. Machine Learning in Analytical Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.2. Quantum chemistry methods  5.3. Computational drug design  5.4. Machine Learning in Chemistry  5.5. Ab initio molecular dynamics
  6. Biophysics and Medicinal Chemistry  6.1. Drug discovery and design  6.2. Enzyme kinetics and inhibition  6.3. Chemical biology approach  6.4. Protein-ligand interactions  6.5. Bioorthogonal chemistry
  7. Materials chemistry  7.1. Polymer chemistry  7.1.1. Polymerization mechanism  7.1.2. Functional Polymers  7.1.3. Biodegradable Polymer  7.1.4. Conducting and semiconducting polymers  7.2. Nano Chemistry  7.2.1. Nanoparticles and nanostructures  7.2.2. Carbon-based nanomaterials  7.2.3. Quantum dots  7.3. Energy and Environmental Chemistry  7.3.1. Battery and Fuel Cell Chemistry  7.3.2. Green chemistry and sustainable materials  7.3.3. Photocatalysis

PHD → Biophysics and Medicinal Chemistry ↓


Enzyme kinetics and inhibition


Enzyme kinetics is an important field of study focused on understanding how enzymes, which are biological catalysts, behave during biochemical reactions. The ability of enzymes to speed up reactions makes them indispensable to life processes, and their efficiency can be affected by various inhibitors. This detailed guide explores enzyme kinetics and inhibition in the fields of biophysical and medicinal chemistry.

Basic concepts of enzyme kinetics

To understand enzyme kinetics, we start with the enzyme itself. Enzymes are proteins that speed up chemical reactions without being consumed in the process. They work by lowering the activation energy needed for the reaction to occur.

Enzyme kinetics involves studying the rates of enzyme-catalyzed reactions. The rate at which an enzyme catalyzes a reaction depends on many factors: substrate concentration, enzyme concentration, temperature, pH, and the presence of inhibitors or activators.

Michaelis–Menten equation

The Michaelis-Menten model is a fundamental concept in enzyme kinetics, which describes the rate of enzymatic reactions by relating the reaction rate to the substrate concentration. The equation is as follows:

v = (Vmax [S]) / (Km + [S])

Where:

  • v is the rate of the reaction.
  • Vmax represents the maximum reaction rate.
  • [S] is the substrate concentration.
  • Km is the Michaelis constant, a measure of the affinity of the enzyme for its substrate.

When [S] is much less than Km, the reaction rate increases linearly with increasing substrate concentration. When [S] is much greater than Km, the rate approaches Vmax.

Visual depiction of enzyme kinetics

Consider the following graph that shows how the reaction velocity v changes with changing substrate concentration [S] according to the Michaelis-Menten equation:

[S] V Vmax

Turnover number and catalytic efficiency

The turnover number, also known as kcat, is the number of substrate molecules converted into product per enzyme molecule per unit time when the enzyme is fully saturated with substrate. It provides a direct measure of the catalytic activity of the enzyme.

Catalytic efficiency is given by the ratio kcat/Km, which relates the rate of product formation to the enzyme-substrate affinity. An enzyme with high catalytic efficiency is highly effective at low substrate concentrations.

Enzyme inhibition

Enzyme inhibition refers to a process in which an inhibitor molecule reduces the activity of an enzyme, slowing the rate of the reaction. Inhibition can be reversible or irreversible.

Types of inhibition

Competitive inhibition

In competitive inhibition, the inhibitor molecule resembles the substrate and competes for binding at the active site. This type of inhibition can be overcome by increasing the substrate concentration.

E + S ⇌ ES → E + PE + I ⇌ EI

Competitive inhibitors increase Km without affecting Vmax.

I I

Non-competitive inhibition

In noncompetitive inhibition, the inhibitor binds to the allosteric site rather than the active site, and the substrate may still bind but not be effectively converted into product.

E + S ⇌ ES → E + PI + E ⇌ EI I + ES ⇌ ESI

Non-competitive inhibitors decrease Vmax while Km remains unchanged.

Non-compete prohibition

In noncompetitive inhibition, the inhibitor binds only to the enzyme-substrate complex, preventing the reaction from completing.

ES + I ⇌ ESI

Both Km and Vmax decrease in noncompetitive inhibition, i.e. the inhibitors further decrease enzyme activity.

[S] V controlled Uncontrolled

Real-world applications

Understanding enzyme kinetics and inhibition is important in many fields. In medicine, enzyme inhibitors serve as drugs. For example:

  • Antibiotics: Penicillin works by inhibiting enzymes that bacteria need to make cell walls.
  • Anticancer drugs: Methotrexate is an anticancer agent that inhibits dihydrofolate reductase, an enzyme in the folic acid metabolism pathway.
  • Statins: Statins, used to lower cholesterol, inhibit HMG-CoA reductase, an enzyme important for cholesterol synthesis.

In the field of biotechnology and research, enzymes and their inhibitors help in understanding metabolic pathways, disease mechanisms, and drug design.

Conclusion

Enzyme kinetics and inhibition are fundamental to biophysics and medicinal chemistry. Enzymes control biochemical reactions and can be modulated by various inhibitors. By studying how enzymes work and how inhibitors affect them, scientists and researchers gain valuable insights into the biochemistry of life and can invent therapeutic drugs.


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Enzyme kinetics and inhibition

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