Related Experiment Videos
Mitochondrial malate dehydrogenase from corn : purification of multiple forms
M K Hayes1, M H Luethy, T E Elthon
1School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0118.
Plant Physiology
|December 1, 1991
Summary
Researchers developed a method to isolate corn mitochondrial proteins. They discovered three distinct forms of malate dehydrogenase, suggesting three nuclear genes encode this important enzyme.
Area of Science:
- Plant Biochemistry
- Mitochondrial Function
- Enzyme Kinetics
Background:
- Mitochondria play a crucial role in cellular respiration and energy production in plants.
- Understanding the composition and function of mitochondrial enzymes is vital for plant physiology research.
- Corn (Zea mays L. B73) mitochondria possess complex enzymatic machinery, including malate dehydrogenase, essential for the Krebs cycle.
Purpose of the Study:
- To develop a robust method for fractionating corn mitochondria into distinct protein components.
- To characterize the malate dehydrogenase (MDH) isoenzymes present in corn mitochondria.
- To investigate the genetic basis of corn mitochondrial MDH diversity.
Main Methods:
- Mitochondrial fractionation using differential centrifugation and protein precipitation.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein separation and molecular mass determination.
- Fast protein liquid chromatography (FPLC) with Mono Q and Phenyl Superose columns for enzyme purification.
- Enzyme activity assays and nondenaturing gel electrophoresis.
- Western blot analysis using polyclonal antibodies against purified MDH.
Main Results:
- A successful fractionation method yielded soluble, high molecular weight soluble, and membrane protein fractions.
- Krebs cycle enzymes, including malate dehydrogenase, were enriched in the soluble fraction.
- Six distinct malate dehydrogenase peaks were purified, revealing three homodimeric and three heterodimeric isoenzymes.
- Analysis indicated three unique monomer subunits with apparent molecular masses of 37, 38, and 39 kilodaltons.
- Nondenaturing gel electrophoresis demonstrated differential mobility for each MDH peak, supporting distinct molecular forms.
Conclusions:
- The findings are consistent with the presence of three nuclear genes encoding corn mitochondrial malate dehydrogenase.
- The developed fractionation and purification techniques provide a valuable tool for studying plant mitochondrial enzymes.
- This study elucidates the complexity of malate dehydrogenase isoenzymes in corn mitochondria, offering insights into metabolic regulation.