Kaiser test

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The Kaiser test is a test that is used in solid-phase peptide synthesis (SPPS) and in organic solid-phase synthesis (SPOS) to monitor turnover. Free amino groups can be detected here quite sensitively and with simple means .

description

The Kaiser test consists of three reagent solutions.

In the presence of free amino groups and thus an incomplete peptide coupling, the solution turns deep violet after heating to about 100 ° C. and can be evaluated optically but also spectroscopically. If the peptide coupling is complete, the solution will turn yellow. The Kaiser test can also be performed quantitatively.

If free amino groups 2 are present , the coupling step has to be repeated, because the endcapping of the free amino groups would, on the one hand, significantly reduce the yield of peptide and, on the other hand, make it more difficult to purify the desired peptide with shorter-chain peptides as impurities.

The Kaiser test is chemically based on the ninhydrin test .

Kaiser test reaction scheme

The dye thus formed is called Ruhemann's Blue 3 . The color of 3 is based, among other things, on an extensive system of conjugated double bonds in and between the two aromatic rings, which should be visualized by the following figure:

AA ninhydrin dye isomerism

The amino acids serine , asparagine , aspartic acid and proline as N -terminal amino acids do not give a clear result in the Kaiser test.

Individual evidence

  1. ^ Emil Thomas Kaiser , Robert L. Colescott, Charles D. Bossinger, Paul I. Cook: Color Test for Detection of Free Terminal Amino Groups in the Solid-Phase Synthesis of Peptides . In: Analytical Biochemistry . tape 34 , no. 2 , 1970, ISSN  0003-2697 , pp. 595-598 , doi : 10.1016 / 0003-2697 (70) 90146-6 .
  2. ↑ Virender K. Sarin, Stephen B. H. Kent , James P. Tam , Robert Bruce Merrifield : Quantitative monitoring of solid-phase peptide synthesis by the ninhydrin reaction . In: Analytical Biochemistry . tape 117 , no. 1 , 1981, ISSN  0003-2697 , pp. 147-157 , doi : 10.1016 / 0003-2697 (81) 90704-1 .
  3. ↑ Weng C. Chan, Peter D. White (Ed.): Fmoc Solid Phase Peptide Synthesis . A practical approach. 1st edition. Oxford University Press , Oxford / New York 2000, ISBN 0-19-963724-5 .
  4. ↑ James Darrell Fontenot, Judith Marchand Ball, Margaret A. Miller, Chaya M. David, Ronald C. Montelaro: A survey of potential problems and quality control in peptide synthesis by the fluorenylmethoxycarbonyl procedure . In: Peptide Research . tape 4 , no. 1 , 1991, p. 19-25 .

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