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Abstract:
Klein, Harold P. (Ames Research Center, Moffett Field, Calif.). Synthesis of fatty acids by yeast particles. J. Bacteriol. 92:130-135. 1966.-When a mitochondria-free homogenate of Saccharomyces cerevisiae was centrifuged at 100,000 x g for 60 min, the sedimented crude particles incorporated acetate into fatty acids, but not into nonsaponifiable lipids. Degradation of the fatty acids formed indicated this to be de novo synthesis rather than chain elongation. Subfractions of the crude particles were obtained. The "ribosomal" fraction was unable to synthesize fatty acids, but had properties indicating the presence of acetokinase, fatty acid desaturase, and, probably, acetyl-coenzyme A carboxylase. A "light" particle fraction with a high specific activity of fatty acid synthetase was also obtained. Fatty acid synthesis by the "soluble" supernatant fluid appeared to be the result of contamination by the "light" particles. The data suggested the presence of several particulate entities in mitochondria-free homogenates.
Insights
Yeast particles from Saccharomyces cerevisiae synthesize fatty acids de novo. A specific light particle fraction demonstrated high fatty acid synthetase activity, indicating distinct cellular components involved in lipid biosynthesis.
Area of Science:
- Biochemistry
- Cell Biology
- Microbiology
Background:
- Lipid biosynthesis is a fundamental cellular process.
- Understanding the localization of metabolic enzymes is crucial for cell biology.
Purpose of the Study:
- To investigate the site of fatty acid synthesis in Saccharomyces cerevisiae.
- To characterize the particulate components involved in de novo fatty acid synthesis.
Main Methods:
- Differential centrifugation of yeast homogenates to isolate cellular fractions.
- Acetate incorporation assays to measure fatty acid synthesis.
- Degradation analysis of synthesized fatty acids.
- Enzyme activity assays for specific enzymes.
Main Results:
- Mitochondria-free yeast particles incorporated acetate into fatty acids via de novo synthesis.
- A "light" particle fraction exhibited high fatty acid synthetase activity.
- The "ribosomal" fraction lacked fatty acid synthesis but contained related enzymes.
- Supernatant fatty acid synthesis was attributed to contamination by "light" particles.
Conclusions:
- Saccharomyces cerevisiae contains distinct particulate entities responsible for fatty acid synthesis.
- Fatty acid synthetase activity is localized to a specific "light" particle fraction.
- The study suggests a compartmentalization of lipid biosynthesis within yeast cells.