Link to the University of Pittsburgh Homepage
Link to the University Library System Homepage Link to the Contact Us Form

Studies of Copper (II) Complexes of Bioactive Peptides

Meng, Rong (2006) Studies of Copper (II) Complexes of Bioactive Peptides. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

Primary Text

Download (1MB) | Preview


Separation-based determinations of peptides hold the promise of measuring the concentrations of many peptides and their metabolites. However, typical chromatographic methods bear disadvantages in their selectivity and/or sensitivities. Thus, means for lowering detection limits are needed. The biuret reaction, the coordination of Cu(II) and peptides in basic solutions, provides a sensitive detection method based on the reversible Cu(III)/Cu(II) electrochemistry in peptide-bonded states.Thyrotropin-releasing hormone (TRH) is an important neuropeptide that undergoes the biuret reaction. The cationic form of TRH is not retained in a typical reversed-phase column. We have modified the common acidic mobile phase for peptide separation with a surfactant to retain the cationic TRH. A surfactant-preconditioned packed-bed capillary serves as the sample loop to preconcentrate TRH through sequential loading. The preconcentration has improved the detection limit for TRH 50-fold in the capillary HPLC-EC system. TRH lacks the N-terminal amine and C-terminal carboxylate that are usually required in the biuret reactions of Cu(II) and tripeptides. The unique structure of TRH affects the electrochemical behavior of the complex. We have utilized various electrochemical and spectroscopic techniques to determine the stoichiometry of the complex and to identify the binding sites in the peptide. Our data reveal that the interactions between Cu(II) and TRH are also possible under physiological pH. The unusual structure of TRH complicates the electrochemistry of Cu(II)-TRH complex. Multiple chemical reactions accompany the redox processes. We have investigated the kinetics of the coupling reactions using a rotating ring-disk electrode. The results suggest deprotonation of the ligand and inter-molecular interactions between complexes. Using microelectrode voltammetry, we have discovered that the octarepeat peptide of the prion protein is involved in Cu(II)/Cu(I) electrochemistry at physiological pH. This observation is relevant to the copper toxicity: Cu(II) may be reduced in vivo to Cu(I), which reacts with hydrogen peroxide to produce damaging oxidative radicals. The octarepeat peptide stabilizes Cu(I) by altering its redox potentials. Thus, the prion protein may have a function of anti-copper-toxicity.


Social Networking:
Share |


Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairWeber, Stephen Gsweber@pitt.eduSWEBER
Committee MemberMichael, Adrianamichael@pitt.eduAMICHAEL
Committee MemberDay, Billybday@pitt.eduBDAY
Committee MemberPetoud, Stephanespetoud@pitt.eduSPETOUD
Date: 2 June 2006
Date Type: Completion
Defense Date: 27 April 2006
Approval Date: 2 June 2006
Submission Date: 24 April 2006
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Copper; electrochemistry; HPLC; peptide; prion; TRH
Other ID:, etd-04242006-214552
Date Deposited: 10 Nov 2011 19:41
Last Modified: 15 Nov 2016 13:42


Monthly Views for the past 3 years

Plum Analytics

Actions (login required)

View Item View Item