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Title: Resolving the Morphology of Peptoid Vesicles at the 1 nm Length Scale Using Cryogenic Electron Microscopy

Abstract

Vesicle formation in a series of amphiphilic sequence-defined polypeptoid block co-polymers comprising a phosphonated hydrophilic block and an amorphous hydrophobic block, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), is studied. The hydrophobic/hydrophilic block ratio was varied keeping the total chain length of the co-polymers constant. A new approach for characterizing the vesicle membrane morphology based on low-dose cryogenic electron microscopy (cryo-EM) is described. The individual low-dose micrographs cannot be interpreted directly due to low signal-to-noise ratio. Sorting and averaging techniques, developed in the context of protein structure determination, were thus applied to vesicle micrographs. Molecular dynamic simulations of the vesicles were used to establish the relationship between membrane morphology and averaged cryo-EM images. This approach enables resolution of the local thickness of the hydrophobic membrane core at the 1 nm length scale. The thickness of the hydrophobic core of the pNeh-b-pNpm membranes increases linearly with the length of the hydrophobic block.

Authors:
ORCiD logo [1];  [1]; ORCiD logo [2];  [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [3]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Qingdao Univ. of Science and Technology, Qingdao (China)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
Publication Date:
Research Org.:
Univ. of California, Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1492105
Alternate Identifier(s):
OSTI ID: 1508807
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Published Article
Journal Name:
Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry
Additional Journal Information:
Journal Volume: 123; Journal Issue: 5; Journal ID: ISSN 1520-6106
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Jiang, Xi, Spencer, Ryan K., Sun, Jing, Ophus, Colin, Zuckermann, Ronald N., Downing, Kenneth H., and Balsara, Nitash P. Resolving the Morphology of Peptoid Vesicles at the 1 nm Length Scale Using Cryogenic Electron Microscopy. United States: N. p., 2019. Web. doi:10.1021/acs.jpcb.8b11752.
Jiang, Xi, Spencer, Ryan K., Sun, Jing, Ophus, Colin, Zuckermann, Ronald N., Downing, Kenneth H., & Balsara, Nitash P. Resolving the Morphology of Peptoid Vesicles at the 1 nm Length Scale Using Cryogenic Electron Microscopy. United States. doi:10.1021/acs.jpcb.8b11752.
Jiang, Xi, Spencer, Ryan K., Sun, Jing, Ophus, Colin, Zuckermann, Ronald N., Downing, Kenneth H., and Balsara, Nitash P. Thu . "Resolving the Morphology of Peptoid Vesicles at the 1 nm Length Scale Using Cryogenic Electron Microscopy". United States. doi:10.1021/acs.jpcb.8b11752.
@article{osti_1492105,
title = {Resolving the Morphology of Peptoid Vesicles at the 1 nm Length Scale Using Cryogenic Electron Microscopy},
author = {Jiang, Xi and Spencer, Ryan K. and Sun, Jing and Ophus, Colin and Zuckermann, Ronald N. and Downing, Kenneth H. and Balsara, Nitash P.},
abstractNote = {Vesicle formation in a series of amphiphilic sequence-defined polypeptoid block co-polymers comprising a phosphonated hydrophilic block and an amorphous hydrophobic block, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), is studied. The hydrophobic/hydrophilic block ratio was varied keeping the total chain length of the co-polymers constant. A new approach for characterizing the vesicle membrane morphology based on low-dose cryogenic electron microscopy (cryo-EM) is described. The individual low-dose micrographs cannot be interpreted directly due to low signal-to-noise ratio. Sorting and averaging techniques, developed in the context of protein structure determination, were thus applied to vesicle micrographs. Molecular dynamic simulations of the vesicles were used to establish the relationship between membrane morphology and averaged cryo-EM images. This approach enables resolution of the local thickness of the hydrophobic membrane core at the 1 nm length scale. The thickness of the hydrophobic core of the pNeh-b-pNpm membranes increases linearly with the length of the hydrophobic block.},
doi = {10.1021/acs.jpcb.8b11752},
journal = {Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry},
number = 5,
volume = 123,
place = {United States},
year = {2019},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1021/acs.jpcb.8b11752

Citation Metrics:
Cited by: 1 work
Citation information provided by
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Figures / Tables:

Table 1 Table 1: Characteristics of the Diblock Polypeptoids pNehm-b-pNpmn

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