Related Experiment Video
Updated: Jun 5, 2026
10:28
A Semi-High-Throughput Adaptation of the NADH-Coupled ATPase Assay for Screening Small Molecule Inhibitors
Published on: August 17, 2019
Fast Motions in 5 Alpha Reductase and Its Impact on Enzyme Kinetics
Rakesh K Roy1, Dimitri Antoniou1, Steven D Schwartz1
1Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States.
ACS Catalysis
|June 4, 2026
Summary
Steroid 5α-reductase type 2 (SRD5A2) enzyme catalysis relies on dynamic residue interactions. Key residues like Tyr33 and L224 enhance efficiency by compressing the donor and modulating the electric field.
Area of Science:
- Biochemistry
- Enzymology
- Computational Biology
Background:
- Enzymes achieve catalytic efficiency through dynamic residue interplay.
- Steroid 5α-reductase type 2 (SRD5A2) facilitates testosterone to dihydrotestosterone conversion via hydride and proton transfer.
Purpose of the Study:
- Investigate SRD5A2's catalytic mechanism, focusing on activation barriers, rate-promoting dynamics, and electrostatic contributions.
- Characterize the role of molecular motion and protein architecture in enzyme kinetics.
Main Methods:
- Utilized Quantum Mechanics/Molecular Mechanics (QM/MM) simulations.
- Employed transition path sampling and committor analysis.
- Analyzed the L224P disease-associated mutant.
Main Results:
- Identified Tyr33 and L224 residues exerting a compression effect, significantly altering free energy barriers and local electric fields, supporting preorganization theory.
- Discovered an extended network of six additional residues (Trp53, Arg94, Cys119, Glu197, Phe223, Arg227) stabilizing transition states via coupled electrostatic and structural interactions.
- Demonstrated that the L224P mutation disrupts compression, eliminates field enhancement, and increases activation barriers by 3.3-3.4 kcal/mol.
Conclusions:
- Efficient SRD5A2 catalysis necessitates the temporal orchestration of dynamics and electrostatics across an extended protein network.
- Protein dynamics and electrostatics are crucial for modulating enzyme activity and function.
- Understanding these mechanisms provides insights into enzyme catalysis and disease-associated mutations.
Related Concept Videos
01:27Fast Reactions
Fast reactions occurring in times shorter than the time needed to mix reactants pose a unique challenge for investigation. In a liquid-phase continuous-flow system, reactants A and B are swiftly pushed into the mixing chamber, where mixing occurs within 1 ms. The reaction mixture then flows through an observation tube, and one measures light absorption to determine species concentrations at various points of the tube. This method is most appropriate when relatively large volumes of reactants...
01:19Enzyme Kinetics
Enzymes speed up reactions by lowering the activation energy of the reactants. The speed at which the enzyme turns reactants into products is called the rate of reaction. Several factors impact the rate of reaction, including the number of available reactants. Enzyme kinetics is the study of how an enzyme changes the rate of a reaction.
Scientists typically study enzyme kinetics with a fixed amount of enzyme in the controlled environment of a test tube. When more reactant, or substrate, is...
Scientists typically study enzyme kinetics with a fixed amount of enzyme in the controlled environment of a test tube. When more reactant, or substrate, is...
01:19Introduction to Enzyme Kinetics
Enzyme kinetics studies the rates of biochemical reactions. Scientists monitor the reaction rates for a particular enzymatic reaction at various substrate concentrations. Additional trials with inhibitors or other molecules that affect the reaction rate may also be performed.
The experimenter can then plot the initial reaction rate or velocity (Vo) of a given trial against the substrate concentration ([S]) to obtain a graph of the reaction properties. For many enzymatic reactions involving a...
The experimenter can then plot the initial reaction rate or velocity (Vo) of a given trial against the substrate concentration ([S]) to obtain a graph of the reaction properties. For many enzymatic reactions involving a...
01:22Factors Influencing the Rate of Chemical Reactions
A variety of factors influence the rate of chemical reactions. For a chemical reaction to happen, atoms must collide with enough energy to overcome the repulsion between their electrons. This energy is called activation energy. Factors influencing the rate of reaction either lower the activation energy or increase the likelihood of a successful collision.
Concentration and Pressure:
The more particles present within a given space, the more likely those particles are to bump into one another.
Concentration and Pressure:
The more particles present within a given space, the more likely those particles are to bump into one another.
01:13Introduction to Mechanisms of Enzyme Catalysis
For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...
01:19Protein Dynamics in Living Cells
Different fluorescence-based techniques are used to study the protein dynamics in living cells. These techniques include FRAP, FRET, and PET.
Fluorescent recovery after photobleaching (FRAP) is a fluorescent-protein-based detection technique used to quantify protein movement rates within the cell. This method exposes a small portion of the cell to an intense laser beam. The laser beam causes permanent photobleaching of the fluorophore-tagged proteins in the exposed region. As the bleached...
Fluorescent recovery after photobleaching (FRAP) is a fluorescent-protein-based detection technique used to quantify protein movement rates within the cell. This method exposes a small portion of the cell to an intense laser beam. The laser beam causes permanent photobleaching of the fluorophore-tagged proteins in the exposed region. As the bleached...