Reduction equivalent

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Reduction equivalent is a unit of measurement used to quantify the reducing power of reducing agents . A reduction equivalent is 1 mol of electrons that are transferred either directly or in the form of hydrogen in redox reactions .

The quantification of reducing agents is important for redox reactions in living things . Several redox reactions are linked by substances that act as electron carriers. This is of particular importance for the respiratory chain , phototrophy and assimilation reactions . Three types of electron carriers, which act as reducing agents after they have absorbed electrons, play a role:

  • Carriers of pure electrons. Examples: cytochromes and ferredoxins . One electron is transferred per molecule . In the reduced state, one mole of the electron carrier thus corresponds to one reduction equivalent .
  • Carriers of electrons in the form of hydrogen atoms. Examples: flavin adenine dinucleotide (FAD) and quinones such as ubiquinone (UQ). Two hydrogen atoms are transferred per molecule. In the reduced state (FADH 2 or UQH 2 ) one mole therefore corresponds to two reduction equivalents.
  • Carriers of pure electrons and hydrogen atoms at the same time. Examples: nicotinamide adenine dinucleotide (NAD, oxidized state: NAD + , reduced state: NADH). In the reduced state, one mole therefore corresponds to two reduction equivalents.

Reduction equivalents are often shown in simplified form as [H].

In common usage in biochemistry and biology - somewhat imprecisely - the reducing agents themselves are referred to as reducing equivalents.

Individual evidence

  1. Albert L. Lehninger: Principles of Biochemistry . Walter de Gruyter, Berlin, New York 1987, p. 520, ISBN 3-11-008988-2 .

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