Natesa Muthukumaraswamy

A useful method for formylation of peptides

Abstract A method of formylation of peptides using formic acid and isovaleroyl chloride is outlined in this communication. Its application for synthesis of several model peptides is also presented.

Synthesis of several chemotactic peptide antagonists.

Abstract The following peptides have been synthesized using classical mixed anhydride methods: Boc-Leu-Phe-OH, Boc-Phe-Leu-Phe-OH, Boc-Leu-Phe-Leu-Phe-OH and Boc-Phe-Leu-Phe-Leu-Phe-OH. The tri, tetra and pentapeptides inhibit Formyl-Met-Leu-Phe-OH induced release of β-glucuronidase from rabbit peritoneal neutrophils. The antagonists exhibit ID 50 concentrations in the range 2.6−5.7×10 −7 M. The dipeptide was inactive at all concentrations tested.

Characteristics of Binding of a Potent Chemotactic Formyl Tetrapeptide, Formylmethionyl-Leucyl-Phenylalanyl- Phenylalanine, to the Receptors on Rabbit Neutrophils

Binding of a potent chemotactic formyl tetrapeptide, formylmethionyl‐leucyl‐phenyl‐alanyl‐phenylalanine (fMet‐Leu‐Phe‐Phe), to the formyl peptide receptors on the rabbit neutrophil was assessed by two approaches. A tritiated preparation of fMet‐Leu‐Phe‐Phe was used for direct binding studies, whereas indirect studies comprised an assessment of the ability of the formyl tetrapeptide to competitively inhibit the binding of 35S‐labeled formylmethionyl‐leucyl‐phenylalanine. These two approaches yielded analogous results. The formyl tetrapeptide fMet‐Leu‐Phe‐Phe showed rapid and saturable binding to the same chemotactic receptors as the less potent formyl tripeptides with which it was compared. Its equilibrium‐binding pattern, however, was different: fMet‐Leu‐Phe‐Phe showed a homogeneous binding pattern, in contrast to the heterogeneity seen with the less potent compounds. The relative potencies for high‐affinity binding of the two standard formyl tripeptides and fMet‐Leu‐Phe‐Phe correlated well with their relative potencies for stimulating the biological response of degranulation; the relative potencies for low‐affinity binding correlated less well.

Stable isotope containing peptides as probes of ligand—receptor interactions: Deutero-formyl-methionyl-leucyl-phenylalanine

The synthesis and biological evaluation of the stable isotope containing chemotactic peptide, deuteroformyl‐methionyl‐leucyl‐phenylalanine (C2DO‐Met‐Leu‐Phe‐OH) is reported. The results, using lysosomal enzyme release from cytochalasin B‐treated rabbit neutrophils for biological evaluation indicates a 3–4 fold enhancement over CHO‐Met‐Leu‐Phe‐OH itself. This is consistent with previous speculation that the formyl proton hydrogen bonds with a critical area of the chemotactic peptide receptor of rabbit neutrophils.

[13] Synthesis of chemotactic peptides

Publisher Summary This chapter discusses the synthesis of the prototype peptide N α formyl-Met-Leu-Phe-OH (fMLP). The steps are a series of repetitive deprotections of t-Boc-amino acids or peptides using trifluoroacetic acid (TFA), subsequent neutralization with N-methyl morpholine (NMM), followed by coupling of the next t-Boc-amino acid using a rapid mixed anhydride method. Although several methods are available for the formylation of peptides, consistently excellent results have been obtained using the anhydride of isovaleryl chloride and formic acid. The same general protocol is used for the synthesis of the antagonists. The prototype analog is the pentapeptide, t-Boc-Phe-Leu-Phe-Leu-Phe-OH. The final step, however, is a catalytic hydrogenolysis to yield the t-Boc-free acid form of the desired peptide. Although the synthesis for the pentapeptide is presented, the tripeptide t-Boc-Phe-Leu-Phe-OH is also fully active and only slightly less potent. No solid-phase synthesis for the antagonists has been reported.