Solid Phase Isotope Exchange of Deuterium and Tritium for Hydrogen in Human Recombinant Insulinстатья
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Дата последнего поиска статьи во внешних источниках: 12 марта 2014 г.
Аннотация:Reaction of a hightemperature solidphase catalytic isotope exchange in peptides and proteins
under the action of the catalytically activated spillover hydrogen was studied. The reaction of human recombinant insulin with deuterium and tritium at 120–140°C resulted in an incorporation of 2–6 isotope hydrogen atoms per one insulin molecule. The distribution of the isotopic label by amino acid residues of the tritium labeled insulin was determined by the oxidation of the protein S–Sbonds by performic acid, separation of polypeptide chains, their subsequent acidic hydrolysis, amino acid analysis, and liquid scintillation counts
of tritium in the amino acids. The isotopic label was shown to be incorporated in all the amino acid residues of the protein, but the higher inclusion was observed for the FVNQHLCGSHLVE peptide fragment (B1–13) of the insulin Bchain, and the His5 and His10 residues of this fragment contained approximately 45% of the whole isotopic label of the protein. Reduction of the S–Sbonds by 2mercaptoethanol, enzymatic hydrolysis by glutamyl endopeptidase from Bacillus intermedius, and HPLC fractionation of the obtained peptides were also used for the analysis of the distribution of the isotopic label in the peptide fragments of the labeled insulin. Peptide fragments which were formed after the hydrolysis of the GluXaa bond of the Bchain were identified by mass spectrometry. The mass spectrometric analysis of the isotopomeric composition of the deuterium labeled insulin demonstrated that all the protein molecules participated equally in the reaction of the solid
phase hydrogen isotope exchange. The tritiumlabeled insulin preserved the complete physiological activity.