The stereochemical effect of SMAP-29 and SMAP-18 on bacterial selectivity, membrane interaction and anti-inflammatory activity

  • Amino Acids. 2016 May;48(5):1241-51. doi: 10.1007/s00726-016-2170-y.
Binu Jacob  1 ,  Ganesan Rajasekaran  1 ,  Eun Young Kim  1 ,  Il-Seon Park  1  2 ,  Jeong-Kyu Bang  3 ,  Song Yub Shin  4  5
Affiliations
  • 1. Department of Medical Science, Graduate School, Chosun University, Gwangju, 501-759, Republic of Korea.
  • 2. Department of Cellular and Molecular Medicine, School of Medicine, Chosun University, Gwangju, 501-759, Republic of Korea.
  • 3. Division of Magnetic Resonance, Korea Basic Science Institute, 804-1 Yangchung-ri, Ochang, Chungbuk, 363-883, Republic of Korea. [email protected].
  • 4. Department of Medical Science, Graduate School, Chosun University, Gwangju, 501-759, Republic of Korea. [email protected].
  • 5. Department of Cellular and Molecular Medicine, School of Medicine, Chosun University, Gwangju, 501-759, Republic of Korea. [email protected].
PMID: 26795535 DOI: 10.1007/s00726-016-2170-y
Abstract

Sheep myeloid antimicrobial peptide-29 (SMAP-29) is a cathelicidin-related antimicrobial peptide derived from sheep myeloid cells. In order to investigate the effects of L-to-D-amino acid substitution in SMAP-29 on Bacterial selectivity, membrane interaction and anti-inflammatory activity, we synthesized its two D-enantiomeric peptides (SMAP-29-E1 and SMAP-29-E2 containing D-Ile and D-allo-Ile, respectively) and two diastereomeric peptides (SMAP-29-D1 and SMAP-29-D2). Additionally, in order to address the effect of L-to-D-amino acid substitution in the N-terminal helical peptide of SMAP-29 (named SMAP-18) on antimicrobial activity, we synthesized its two D-enantiomeric peptides (SMAP-18-E1 and SMAP-18-E2), which are composed of D-amino acids entirely. L-to-D-amino acid substitution in membrane-targeting AMP, SMAP-29 did not affect its antimicrobial activity. However, D-allo-Ile containing-SMAP-29-E2 and SMAP-29-D2 exhibited less hemolytic activity compared to D-Ile containing-SMAP-29-E1 and SMAP-29-D1, respectively. L-to-D-amino acid substitution in intracellular targeting-AMPs, SMAP-18 and buforin-2 improved antimicrobial activity by 2- to eightfold. The improved antimicrobial activity of the D-isomers of SMAP-18 and buforin-2 seems to be due to the stability against proteases inside Bacterial cells. Membrane depolarization and dye leakage suggested that the membrane-disruptive mode of SMAP-29-D1 and SMAP-29-D2 is different from that of SMAP-29, SMAP-29-E1, and SMAP-29-E2. L-to-D-amino acid substitution in SMAP-29 improved anti-inflammatory activity in LPS-stimulated RAW 264.7 cells. In summary, we propose here that D-allo-Ile substitution is a more powerful strategy for increasing Bacterial selectivity than D-Ile substitution in the design of D-enantiomeric and diastereomeric AMPs. SMAP-29-D1, and SMAP-29-D2 with improved Bacterial selectivity and anti-inflammatory activity can serve as promising candidates for the development of anti-inflammatory and antimicrobial agents.

Keywords
Anti-inflammatory activity; Bacterial selectivity; L-to-D-amino acid substitution; Protease stability; SMAP-29/SMAP-18.
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