http://jcps.bjmu.edu.cn

Journal of Chinese Pharmaceutical Sciences ›› 2019, Vol. 28 ›› Issue (11): 749-759.DOI: 10.5246/jcps.2019.11.071

• Original articles •     Next Articles

Membrane binding of the pH sensitive antimicrobial peptide LAH4 studied by EPR spectroscopy

Yina Sheng1, Shenlin Wang2, Guoquan Liu1*   

  1. 1. State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
    2. College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
  • Received:2019-06-13 Revised:2019-08-24 Online:2019-12-01 Published:2019-09-19
  • About author:Tel: +86-10-82801517, E-mail: guoquanliu@bjmu.edu.cn
  • Supported by:

    Seed Fund of Peking University (Grant No. BMU2018MC003), Peking University Health Science Center (Grant No. BMU20160566), and the National Key Research and Development Program of the Ministry of Science and Technology of the People’s Republic of China (Grant No. 2016YFA0501203) and the National Natural Science Foundation of China (Grant No. 31470727, 21874004).

Abstract:

Peptide-membrane binding is vital for many biological events, including the bacteria combating by antimicrobial peptides. Using the pH sensitive LAH4 peptide as model, we employed a convenient electron paramagnetic resonance (EPR) method to study the peptide-membrane binding process in artificial phospholipid membranes. Based on spectral changes of the nitroxide radicallabeled to the peptides, we characterized binding kinetics and affinity of peptides to different phospholipid membranes. The binding affinity of LAH4 towards POPG was more than an order of magnitude higher than those towards DMPC and POPC. The binding kinetics showed that LAH4 initially bound to POPG much more quickly than to DMPC and POPC. Additionally, pH also affected the binding kinetics in LAH4-membrane interactions, which helped explain the pH dependent antimicrobial activity of LAH4. The method might be further used to monitor the membrane binding/cell penetration of antimicrobial peptide in living cells.

Key words: EPR, AMPs, Peptide-membrane interaction

CLC Number: 

Supporting:

 

Figure S1. The chromatograms of LAH4-26SL.

 

 

 

Figure S2. The Q-TOF-Mass spectrogram of purified LAH4-26SL of [M+4H]4+ (right) and [M+5H]5+ (left).

 

 

 

Figure S3. Room temperature X-band EPR spectrum of LAH4-26SL bound to different phospholipid vesicles. Peptide concentration is 100 μM. (a) DMPC, pH = 7.0 with buffer; (b) POPC: pH = 5.4 without buffer.

 

 

 

Figure S4. Dependence of the 1/Rb on P/L to calculate the distribution coefficient. Peptide concentration is 50 μM.

 

 

 

Figure S5. EPR spectra of LAH4-26SL mixing with lipid vesicles after 10s vortex. Peptide concentration is 100 μM.

 

 

 

Figure S6. (a) EPR spectra of LAH4-26SL mixing with DMPC vesicles in PBS at pH = 5.0 mixed without vortex. Peptide concentration is 100 μM. L/P=1000. “0 min” means the state of LAH4-26SL before mixed with DMPC vesicles. (b) Evolution of IHF in DMPC vesicles in PBS at pH = 5.0 mixed without vortex. Peptide concentration is 100 μM. L/P=1000.