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Biophysics of structure and mechanism

, Volume 10, Issue 4, pp 197–204 | Cite as

Structure of ascorbic acid and its biological function

I. ESR determination of the ascorbyl radical in biological samples and in model systems
  • W. Lohmann
  • D. Holz
Article

Abstract

ESR investigations on lyophilized systems have shown that the signal at g = 2.005 can be explained by an interaction between Na+ or K+ and the anionic ascorbyl radical. The unpaired electron is probably localized near the C(4) region and is produced by a cleavage of an H atom belonging to a water molecule bound tightly to C(4). Experiments on aqueous samples revealed that ascorbic acid in its radical configuration and in its highest concentration exists only at physiological pH and temperature. An additional splitting is obtained by the ring formation between C(3) and C(6)-OH. The coupling constants of the triplets produced by the CH2-6 protons differ between ascorbic acid and isoascorbic acid. Thus, the ESR technique can be applied for an easy distinction between these two epimers.

Key words

Ascorbic acid ESR Na+ K+ 

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Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • W. Lohmann
    • 1
  • D. Holz
    • 1
  1. 1.Institut für Biophysik im Strahlenzentrum der UniversitÄtGiessenFederal Republic of Germany

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