Detection of neuropeptides using on-capillary copper complexation and capillary electrophoresis with electrochemical detection.
Capillary electrophoresis with electrochemical detection using a carbon fiber electrode in conjunction with on-capillary copper complexation was evaluated for the determination of peptides in standard and biological matrices. Peptides composed of 2-10 amino acids were investigated. A comparison was made between the responses obtained for peptides containing the oxidizable residue tyrosine and those obtained for their respective copper complexes. Electrochemical detection of non-tyrosine-containing peptides and a cyclic peptide was also demonstrated. A separation of leucine (Leu)-enkephalin and five metabolites was developed and then used for the investigation of Leu-enkephalin metabolism in plasma. The appearance of the des-tyrosine (des-Tyr) Leu-enkephalin, which cannot be detected directly at a carbon electrode, was monitored using the on-capillary complexation technique. Direct injection of the plasma sample was possible using this methodology.
Gawron
A J
AJ
Department of Pharmaceutical Chemistry, University of Kansas, Lawrence 66047, USA.
Lunte
S M
SM
D000809:Angiotensins / Q000032:analysis; D003300:Copper; D004563:Electrochemistry / Q000379:methods; D019075:Electrophoresis, Capillary / Q000379:methods; D004743:Enkephalin, Leucine / Q000097:blood; D006801:Humans; D009479:Neuropeptides / Q000032:analysis* / Q000097:blood / Q000737:chemistry; D009842:Oligopeptides / Q000032:analysis* / Q000737:chemistry; D010456:Peptides, Cyclic / Q000032:analysis / Q000737:chemistry; D013329:Structure-Activity Relationship; D014443:Tyrosine
D000809:Angiotensins; D009479:Neuropeptides; D009842:Oligopeptides; D010456:Peptides, Cyclic; D014443:Tyrosine; D004743:Enkephalin, Leucine; D003300:Copper