The 32-residue peptide, RK-1, a novel kidney-derived three disulfide-bonded member of the antimicrobial alpha-defensin family, was synthesized by the continuous flow Fmoc-solid phase method. The crude, cleaved and S-reduced linear peptide was both efficiently folded and oxidized in an acidic solution of aqueous dimethyl sulfoxide. Following purification of the resulting product, it was shown by a variety of analytical techniques, including matrix assisted laser desorption time of flight mass spectrometry, to possess a very high degree of purity. The disulfide bond pairing of the synthetic peptide was determined by 1H-NMR spectroscopy and confirmed to be a Cys1-Cys6, Cys2-Cys4, Cys3-Cys5 arrangement similar to other mammalian alpha-defensin peptides. The synthetic RK-1 was also shown to inhibit the growth of Escherichia coli type strain NCTC 10418.

Residue (chemistry)

Peptide Synthesis

Cyclic peptide

Sulfoxide

Solid-Phase Synthesis

10.1002/(sici)1099-1387(200001)6:1<19::aid-psc230>3.0.co;2-1

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Citations (15)

Three-Dimensional Structure of RK-1: A Novel α-Defensin Peptide

Biochemistry (2000)

Ailsa M. McManus Nicola F. Dawson John D. Wade Lyle E. Carrington Don Winzor

NMR spectroscopy and simulated annealing calculations have been used to determine the three-dimensional structure of RK-1, an antimicrobial peptide from rabbit kidney recently discovered from homology screening based on the distinctive physicochemical properties of the corticostatins/defensins. RK-1 consists of 32 residues, including six cysteines arranged into three disulfide bonds. It exhibits antimicrobial activity against Escherichia coli and activates Ca2+ channels in vitro. Through its physicochemical similarity, identical cysteine spacing, and linkage to the corticostatins/defensins, it was presumed to be a member of this family. However, RK-1 lacks both a large number of arginines in the primary sequence and a high overall positive charge, which are characteristic of this family of peptides. The three-dimensional solution structure, determined by NMR, consists of a triple-stranded antiparallel β-sheet and a series of turns and is similar to the known structures of other α-defensins. This has enabled the definitive classification of RK-1 as a member of this family of antimicrobial peptides. Ultracentrifuge measurements confirmed that like rabbit neutrophil defensins, RK-1 is monomeric in solution, in contrast to human neutrophil defensins, which are dimeric.

Antiparallel (mathematics)

10.1021/bi000457l

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Citations (30)

Relaxin 3, a novel member of the insulin/relaxin superfamily of peptide hormones.

Ross A. D. Bathgate Daniel J. Scott Chrishan S. Samuel T.C.D. Burazin Sharon Layfield

Relaxin

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