Related Experiment Video
Updated: Jun 26, 2026
07:17
Non-equilibrium Microwave Plasma for Efficient High Temperature Chemistry
Published on: August 1, 2017
Faster superoxide dismutase mutants designed by enhancing electrostatic guidance.
E D Getzoff1, D E Cabelli, C L Fisher
1Department of Molecular Biology, Scripps Research Institute, La Jolla, California 92037.
Nature
|July 23, 1992
Summary
Copper, Zinc Superoxide Dismutase (SOD) enzymes protect cells from oxidative damage. Enhancing electrostatic guidance in SOD
Area of Science:
- Biochemistry
- Enzymology
- Structural Biology
Background:
- Copper, Zinc Superoxide Dismutase (SOD) is a crucial enzyme protecting against oxidative damage.
- SOD dismutes superoxide radicals to oxygen and hydrogen peroxide, a reaction enhanced by electrostatic guidance.
- Human SOD exhibits rapid kinetics (Vmax ≈ 2 x 10^9 M-1 s-1) due to efficient active-site mechanisms.
Purpose of the Study:
- To investigate the role of electrostatic guidance in enhancing SOD reaction rates.
- To determine if increasing positive charge at the active site can further accelerate SOD activity.
- To understand the structural requirements for optimizing electrostatically facilitated diffusion in enzymes.
Main Methods:
- Site-specific mutagenesis of human SOD to alter active-site charge distribution.
- Kinetic assays to measure enzyme reaction rates and ionic-strength dependence.
- Brownian dynamics simulations incorporating electrostatic interactions to model reaction mechanisms.
Main Results:
- Mutants with increased positive charge and maintained hydrogen-bonding network (Glu→Gln) showed faster reaction rates.
- These mutants exhibited increased ionic-strength dependence, consistent with simulations.
- A charge-reversal mutant (Glu→Lys) was slower than charge-neutralization mutants, indicating disruption of the orienting network.
Conclusions:
- Optimizing electrostatically facilitated diffusion in SOD is achievable through targeted mutagenesis.
- Maintaining the structural integrity of the active-site electrostatic network is critical for enhancing enzyme rates.
- Enzyme design can be guided by understanding the interplay between charge, structure, and diffusion-limited reactions.
More Related Videos
Related Concept Videos
02:50Catalysis
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
01:46Oxidative Cleavage of Alkenes: Ozonolysis
In ozonolysis, ozone is used to cleave a carbon–carbon double bond to form aldehydes and ketones, or carboxylic acids, depending on the work-up.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
02:57Sharpless Epoxidation
The conversion of allylic alcohols into epoxides using the chiral catalyst was discovered by K. Barry Sharpless and is known as Sharpless epoxidation. The use of a chiral catalyst enables the formation of one enantiomer of the product in excess. This chiral catalyst is mainly a chiral complex of titanium tetraisopropoxide and tartrate ester (specific stereoisomer). The stereoisomer used in the chiral catalyst dictates the formation of the enantiomer of the product. In other words, the use of...
01:07Catalytically Perfect Enzymes
The theory of catalytically perfect enzymes was first proposed by W.J. Albery and J. R. Knowles in 1976. These enzymes catalyze biochemical reactions at high-speed. Their catalytic efficiency values range from 108-109 M-1s-1. These enzymes are also called 'diffusion-controlled' as the only rate-limiting step in the catalysis is that of the substrate diffusion into the active site. Examples include triose phosphate isomerase, fumarase, and superoxide dismutase.
01:43Electron Transport Chain: Complex III and IV
During the electron transport chain, electrons from NADH and FADH2 are first transferred to complexes I and II, respectively. These two complexes then transfer the electrons to ubiquinol, which carries them further to complex III. Complex III passes the electrons across the intermembrane space to Cyt c, which carries them further to complex IV. Complex IV donates electrons to oxygen and reduces it to water. As electrons pass through complexes I, III, and IV, the energy released aids the pumping...
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...