title: Temperature-dependent instability of the cTnI subunit in NIST SRM2921 characterized by tryptic peptide mapping.
abstract: In this study temperature-dependent instability of the cTnI subunit of the three-protein complex NIST SRM2921 was demonstrated using a mass spectrometric tryptic peptide mapping approach. The results were compared to the cTnI subunit obtained as a protein standard from Calbiochem with identical amino acid sequence. Both the three-protein complex from NIST as well as the cTnI subunit were incubated at elevated temperatures and then evaluated with respect to the primary sequence. The corresponding peptide maps were analyzed using LC-MS/MS. From a Mascot database search in combination with "semiTrypsin" tolerance it was found that two peptide backbone cleavages had occurred in subunit cTnI in NIST SRM2921 material upon incubation at 37°C, namely between amino acids at 148/149 and 194/195. The Calbiochem standard did not show increased levels of "unexpected" peptides in tryptic peptide maps. One of the two peptide backbone cleavages could also be monitored using a "single-step" MALDI-MS approach, i.e. without the need for peptide separation. The amount of degradation appeared rather constant in replicate temperature-instability experiments. However, for accurate quantification internal labelled standards are needed.
authors: Leiden University Medical Center (LUMC), Department of Parasitology, Biomolecular Mass Spectrometry Unit, Albinusdreef 2, 2300 RC, Leiden, The Netherlands. Y.E.M.van der Burgt@lumc.nl
authors: Yuri E M
authors: YE
authors: van der Burgt
authors: Christa M
authors: CM
authors: Cobbaert
authors: Hans
authors: H
authors: Dalebout
authors: Nico
authors: N
authors: Smit
authors: André M
authors: AM
authors: Deelder
mesh_terms: D000595:Amino Acid Sequence; D002853:Chromatography, Liquid; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D010449:Peptide Mapping / Q000379:methods* / Q000592:standards; D055550:Protein Stability; D021122:Protein Subunits; D012015:Reference Standards; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry; D014336:Troponin / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D021122:Protein Subunits; D014336:Troponin; D014357:Trypsin