C-11 Labeling of Peptides in a Single Step

SITE-SPECIFIC 11 C -LABELING OF PEPTIDES USING [ 11 C ]METHYLATING AGENTS By Erin Saucke-Lacelle, Esther Schirrmacher, Dean Jolly, Ralf Schirrmacher

OBJECTIVE site-specific labeling of unprotected peptides using 11 C methylating agents in one-step

ALREADY DONE
Proved principal of using 11C-peptide tracers;
Proposed finding a faster + suitable method for methylation
Labelling agent: [ 11 C]Methoxy-benzaldehyde -Wester et. al, Munich, 2004

METHOD
type of solvent
treat peptides with base
reaction temperature
precursor concentration
[ 11 C]Methyliodide [ 11 C]Methyltriflate [ 11 C]Methylnonaflate
Parameters tested
methylating agent:

Trp-Tyr-Phe-Phe-Lys-Gly 5 side chains 3 possibilities HPLC conditions: Agilent 1200 series multiwavelength UV, Raytest radioactivity detector, LiChrosorb column 250 x 10mm, flow 2.0 ml/min, ACCN (0.05%TFA)/H2O (0.05% TFA), gradient from 100% H2O to 0% within 40 min

Trp-Tyr-Trp-Ser-Arg-Cys-Lys-Trp-Thr-Gly 9 side chains 7 possibilities HPLC conditions: Agilent 1200 series multiwavelength UV, Raytest radioactivity detector, Chromolith column 100 x 4.6mm, flow 1.4 ml/min, H2O(0.05%TFA)/ ACCN(0.05% TFA), gradient from 100% H2O to 0% within 40 min

RESULTS- Optimum reaction parameters
TEMPERATURE
Always room temperature
SML precursor concentration (& amount?)
≥ 0.13mg peptide (1.5x10 -4 mmol or 0.15 μ mol)
0.001 mmol/mL
LGE precursor concentration (& amount?)
≥ 0.15mg peptide (1x10 -4 mmol or 0.1 μ mol)
0.00084 mmol/mL
[11C]Methyliodide [11C]Methyltriflate [11C]Methylnonaflate 6-mere DCM X N-terminal (2,3) n/a AcCN (6% H2O) X N-terminal (2,3), TYR (2,3) N-terminal (2,3), TYR (2,3) 10-mere DCM X X n/a AcCN (6% H2O) X CYS (3,4,5,6,7) X [11C]Methyliodide [11C]Methyltriflate [11C]Methylnonaflate 6-mere DCM X N-terminal (2,3) n/a AcCN (6% H2O) X N-terminal (2,3), TYR (2,3) N-terminal (2,3), TYR (2,3) 10-mere DCM X X n/a AcCN (6% H2O) X CYS (3,4,5,6,7) n/a

CONCLUSION
Methylated:
Large peptide: Cys
Small peptide: N-terminal
RCY of up to 80% within 10 min rxn time
Total synthesis time (EOB): 35-55 min depending on work-up

ACKNOWLEDGEMENTS
-Fahim Moussi
-Dr. Ralf Schirrmacher
-Dr. Esther Schirrmacher
-Dean Jolly
-Michael Kosters
-Miriam Kovacevic
-Dr. Gassan Massarweh
-Antoun Bou Laouz
-Julian Goodstein
-Dr. Markus Holschbach

C-11 Labeling of Peptides in a Single Step

by ErinSauckeLacelle on Oct 28, 2009

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C-11 Labeling of Peptides in a Single Step — Presentation Transcript