A practical synthesis of the ¹³C/¹⁵N- labelled tripeptide N-formyl- Met-Leu-Phe, useful as a reference in solid- state NMR spectroscopy

• Sven T. Breitung,
• Jakob J. Lopez,
• Gerd Dürner,
• Clemens Glaubitz,
• Michael W. Göbel and
• Marcel Suhartono

Beilstein J. Org. Chem. 2008, 4, No. 35, doi:10.3762/bjoc.4.35

• 13C/15N-labelled tripeptide 1 could be isolated in a typical batch. This peptide can be easily crystallised and is therefore well suited as a standard sample for setting up solid-state NMR experiments. Keywords: Fmoc solid phase peptide synthesis; formylation; f-MLF; magic-angle spinning; Wang resin

• shifts for setting up correlation spectra. The 13C/15N-labelled tripeptide N-formyl-Met-Leu-Phe-OH (f-MLF-OH) (1) has been shown in a number of solid-state NMR studies to fulfil these criteria. It has been used in great detail to examine spin dynamics in peptide and for distance measurements [1][2][3][4

• ][5][6][7][8][9]. MLF is a chemotactic peptide which plays an important role in antibody research [10]. Although this tripeptide was briefly commercially available in the past, only one synthesis of f-MLF-OH (1) by solid phase methods has been published so far [11]. Rigorous reaction conditions (EtOH