Engineering disulfide bonds of the novel human beta-defensins hBD-27 and hBD-28: differences in disulfide formation and biological activity among human beta-defensins.
Human beta-defensins comprise a large number of peptides that play a functional role in the innate and adaptive immune system. Recently, clusters of new beta-defensin genes with predominant expression in testicular tissue have been discovered on different chromosomes by bioinformatics. beta-Defensins share a common pattern of three disulfides that are essential for their biological effects. Here we report for the first time the chemical synthesis of the new fully disulfide-bonded beta-defensins hBD-27 and hBD-28, and compare the results with synthetic procedures to obtain the known hBD-2 and hBD-3. While hBD-27 was readily converted into a product with the desired disulfide pattern by oxidative folding, hBD-28 required a selective protective group strategy to introduce the three disulfide bonds. The established synthetic processes were applied to the synthesis of hBD-2, which, like hBD-27, was accessible by oxidative folding, whereas hBD-3 required a selective strategy comparable to hBD-28. Experimental work demonstrated that trityl, acetamidomethyl, and t-butyl are superior to other protection strategies. However, the suitable pairwise arrangement of the protective groups can be different, as shown here for hBD-3 and hBD-28. Determination of the minimum inhibitory concentration against different bacteria revealed that hBD-27, in contrast to other beta-defensins tested, has virtually no antimicrobial activity. Compared to the other peptides tested, hBD-27 showed almost no cytotoxic activity, measured by hemoglobin release of erythrocytes. This might be due to the low positive net charge, which is significantly higher for hBD-2, hBD-3, and hBD-28.
Schulz
Axel
A
IPF PharmaCeuticals GmbH, Feodor-Lynen-Strasse 31, D-30625 Hannover, Germany. a.schulz@ipf-pharmaceuticals.de
Klüver
Enno
E
Schulz-Maronde
Sandra
S
Adermann
Knut
K
D000595:Amino Acid Sequence; D003545:Cysteine; D004220:Disulfides / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D023083:beta-Defensins / Q000138:chemical synthesis / Q000737:chemistry*
D004220:Disulfides; D010446:Peptide Fragments; D023083:beta-Defensins; C500654:beta-defensin 28, human; C500653:beta-defensin-27, human; D003545:Cysteine