Degradation of aspartyl peptides [Elektronische Ressource] : studies on the isomerization and enantiomerization of aspartic acid in model peptides by capillary electrophoresis and high performance liquid chromatography / von Silvia De Boni

Degradation of Aspartyl Peptides Studies on the isomerization and enantiomerization of aspartic acid in model peptides by capillary electrophoresis and high performance liquid chromatography Dissertation zur Erlangung des akademischen Grades Doctor rerum naturalium (Dr. rer. nat.) vorgelegt dem Rat der Biologisch – Pharmazeutischen Fakultät der Friedrich – Schiller – Universität Jena von Diplom – Pharmazeutin Silvia De Boni geboren am 23. Juli 1975 in Conegliano (Italien) Gutachter: 1. Prof. Dr. G. Scriba 2. Prof. Dr. J. Lehmann 3. Prof. Dr. G. Blaschke Tag der mündlichen Prüfung: 14.12.2004 Tag der öffentlichen Verteidigung: 25.01.2005 For Jan Contents I Contents 1. Introduction 1 1.1 Instability of aspartyl peptides 1 1.2 Analytical techniques to investigate aspartic acid degradation 3 1.3 Aim of the work 4 2. Synthesis of reference substances 6 2.1 Solid phase peptide synthesis of tripeptides with free terminal carboxyl group 6 2.2 Synthesis of succinimidyl peptides 7 3. Incubation of model peptides 9 3.1 Incubation of Phe-Asp-GlyNH and Gly-Asp-PheNH 9 2 2 3.2 Incubation of Phe-Asu-GlyOH 9 4. Analysis of degradation products by capillary electrophoresis 10 4.1 Basic principles of peptide analysis by CE 10 4.2 Analysis by CE in achiral buffer 11 4.