Tohoku University

Sumio Ohtsuki

Tetsuya Terasaki

Junichi Kamiie

Disclosed is an evaluation peptide for evaluating the efficiency of a pretreatment in the quantification of a protein using a mass spectrometer, having high reliability and high general versatility. Also disclosed is an artificial standard protein comprising the evaluation peptide. Further disclosed is a method for quantifying a protein utilizing the artificial standard protein. Specifically disclosed is a method for selecting a peptide which consists of an amino acid sequence not agreeing with that in a naturally occurring protein and a variant thereof and capable of being detected by mass spectrometry and which has an amino acid that can be recognized by a protein-digesting enzyme, and using the peptide as an evaluation peptide for use in the quantification of a protein by a mass spectrometer.

Evaluation peptide for use in quantification of protein using mass spectrometer, artificial standard protein, and method for quantifying protein

An object of the present invention is to provide a method for producing a stable isotope-labeled target peptide fragment in mass spectrometry, which achieves inexpensive and convenient production. As a solution to attain the object, the stable isotope-labeled target peptide fragment in mass spectrometry is produced using a method comprising the steps of: expressing a DNA conjugate in a system having a stable isotope-labeled amino acid to thereby prepare a stable isotope-labeled protein, wherein the DNA conjugate comprises: a tandemly linked DNA in which two or more DNAs encoding one or more types of target peptide fragments are linked in tandem; and a DNA encoding a peptide fragment for concentration measurement; subjecting the stable isotope-labeled protein to fragmentation treatment with trypsin to prepare a stable isotope-labeled peptide fragment for concentration measurement and stable isotope-labeled target peptide fragments; quantifying the stable isotope-labeled peptide fragment for concentration measurement using a liquid chromatograph-tandem mass spectrometer (LC/MS/MS); and calculating the concentration of the stable isotope-labeled target peptide fragment of each type from the quantification value of the stable isotope-labeled peptide fragment for concentration measurement.

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Miyagi, Japan

Sumio Ohtsuki