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Redox Disproportionation of Glucose as a Major Biosynthetic Energy SourcePrevious studies have concluded that very little if any energy is required for the microbial biosynthesis of amino acids and lipids from glucose -- processes that yield almost as much ATP (adenosine triphosphate) as they consume. However, these studies did not establish the strength nor the nature of the energy source driving these biological transformations. To identify and estimate the strength of the energy source behind these processes, we calculated the free energy change due to the redox disproportionation of substrate carbon of (a) 26 redox-balanced fermentation reactions, and (b) the biosynthesis of amino acids, lipids, and nucleotides of E. coli from glucose. A plot of the negative free energy of these reactions per mmole of carbon as a function of the number of disproportionative electron transfers per mmol of carbon showed that the energy yields of these fermentations and biosyntheses were directly proportional to the degree of redox disproportionation of carbon. Since this linear relationship showed that redox disproportionation was the dominant energy source of these reactions, we were able to establish that amino acid and lipid biosynthesis obtained most of their energy from redox disproportionation (greater than 94%). In contrast nucleotide biosynthesis was not driven by redox disproportionation of carbon, and consequently depended completely on ATP for energy. This crucial and previously unrecognized role of sugars as an energy source of biosynthesis suggests that sugars were involved at the earliest stage in the origin of anabolic metabolism.
Document ID
19990087890
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Weber, Arthur L.
(Search for Extraterrestrial Intelligence Inst. Moffett Field, CA United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1996
Subject Category
Space Biology
Meeting Information
Meeting: Origin of Life
Location: Ventura, CA
Country: United States
Start Date: January 7, 1996
End Date: January 12, 1996
Distribution Limits
Public
Copyright
Other

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