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J Bacteriol. 1965 March; 89(3): 839-847
Copyright © 1965 American Society for Microbiology. All Rights Reserved.

Characteristics and Intermediates of Short-Term C¹⁴O₂ Incorporation During Ribose Oxidation by Hydrogenomonas facilis¹

^a Department of Chemistry, Washington State University, Pullman, Washington

ABSTRACT

MCFADDEN, B. A. (Washington State University, Pullman), AND H. R. HOMANN. Characteristics and intermediates of short-term C¹⁴O₂ incorporation during ribose oxidation by Hydrogenomonas facilis. J. Bacteriol. 89:839–847. 1965.—Ribose-grown cells of Hydrogenomonas facilis, which had been suspended in growth medium and were oxidizing ribose, were exposed to HC¹⁴O₃^– of high specific activity. The uptake was proportional to cell mass. Short-term uptake (less than 2 min) was completely inhibited by 10^–3M 2,4-dinitrophenol (DNP) or by <4 x 10^–6Mm-chlorocarbonyl cyanide phenylhydrazone, and to the extent of 42% by 5 x 10^–5M DNP. The following observations were made in kinetic studies (8, 16, 35, 67, 96, and 181 sec) of fixation in the presence of ribose. Glutamate was extensively labeled in periods up to 3 min. It was one of the major early products, containing 30% of the label at 8 sec. The sugar phosphate fraction was not detectably labeled at 8 or 16 sec, but its C¹⁴-content increased rapidly to 27% at 35 sec and then slowly decreased. Label in phosphoglycerate, phosphoenolpyruvate, and alanine did not appear until 35 sec, and did not exceed about 7, 2, and 3%, respectively, of the total extracted radioactivity. Adenosine triphosphate and adenosine diphosphate were heavily labeled after fixation in a pilot study for 125 sec. Although considerable radioactivity incorporated during the pilot study was intractable by the extraction procedure employed, virtually no C¹⁴ was found in the residue in poly-ß-hydroxybutyric acid. A large number of amino acids and organic acids and some organic phosphates were not detectably labeled in any of the experiments. Omission of ribose greatly diminished incorporation, particularly into glutamate.

² Present address: Concordia College, Moorhead, Minn.

¹ Material in this paper was taken in part from dissertation of H. R. Homann, presented to the Graduate Faculty of Washington State University in partial fulfillment of requirements for the Ph.D. degree.