title: Peptide quantification by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry: investigations of the cyclotide kalata B1 in biological fluids.
abstract: A rapid method has been developed for the quantification of the prototypic cyclotide kalata B1 in water and plasma utilizing matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry. The unusual structure of the cyclotides means that they do not ionise as readily as linear peptides and as a result of their low ionisation efficiency, traditional LC/MS analyses were not able to reach the levels of detection required for the quantification of cyclotides in plasma for pharmacokinetic studies. MALDI-TOF-MS analysis showed linearity (R2 > 0.99) in the concentration range 0.05-10 microg/mL with a limit of detection of 0.05 microg/mL (9 fmol) in plasma. This paper highlights the applicability of MALDI-TOF mass spectrometry for the rapid and sensitive quantification of peptides in biological samples without the need for extensive extraction procedures.
authors.affiliation: Institutefor Molecular Bioscience, University of Queensland, ARC Special Research Centre for Functional and Applied Genomics, Brisbane 4072, Australia.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Colgrave
authors.forename: Alun
authors.initials: A
authors.lastname: Jones
authors.forename: David J
authors.initials: DJ
authors.lastname: Craik
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001826:Body Fluids / Q000737:chemistry*; D002138:Calibration; D047169:Cyclotides / Q000032:analysis* / Q000737:chemistry; D007275:Injections, Intravenous; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D011487:Protein Conformation; D051381:Rats; D017207:Rats, Sprague-Dawley; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D047169:Cyclotides; C091930:kalata B1