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Title: Mineral Surfaces as Agents of Environmental Proteolysis: Mechanisms and Controls

Abstract

Here, we investigated the extent to which contact with mineral surfaces affected the molecular integrity of a model protein, with an emphasis on identifying the mechanisms (hydrolysis, oxidation) and conditions leading to protein alteration. To this end, we studied the ability of four mineral surface archetypes (negatively charged, positively charged, neutral, redox-active) to abiotically fragment a well-characterized protein (GB1) as a function of pH and contact time. GB1 was exposed to the soil minerals montmorillonite, goethite, kaolinite, and birnessite at pH 5 and pH 7 for 1, 8, 24, and 168 h and the supernatant was screened for peptide fragments using Tandem Mass Spectrometry. To distinguish between products of oxidative and hydrolytic cleavage, we combined results from the SEQUEST algorithm, which identifies protein fragments that were cleaved hydrolytically, with the output of a deconvolution algorithm (DECON-Routine) designed to identify oxidation fragments. All four minerals were able to induce protein cleavage. Manganese oxide was effective at both hydrolytic and oxidative cleavage. The fact that phyllosilicates—which are not redox active—induced oxidative cleavage indicates that surfaces acted as catalysts and not as reactants. Our results extend previous observations of proteolytic capabilities in soil minerals to the groups of phyllosilicates and Fe-oxides. We identifiedmore » structural regions of the protein with particularly high susceptibility to cleavage (loops and β strands) as well as regions that were entirely unaffected (α helix).« less

Authors:
ORCiD logo [1];  [2];  [3]; ORCiD logo [4];  [4];  [4]; ORCiD logo [4];  [3];  [4];  [3]
  1. Oregon State Univ., Corvallis, OR (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Oregon State Univ., Corvallis, OR (United States)
  3. Oregon State Univ., Corvallis, OR (United States)
  4. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); USDOE Office of Science (SC), Workforce Development for Teachers and Scientists (WDTS) (SC-27)
OSTI Identifier:
1503671
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Environmental Science and Technology
Additional Journal Information:
Journal Volume: 53; Journal Issue: 6; Journal ID: ISSN 0013-936X
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Chacon, Stephany S., Reardon, Patrick N., Burgess, Christopher J., Purvine, Samuel, Chu, Rosalie K., Clauss, Therese R., Walter, Eric, Myrold, David D., Washton, Nancy, and Kleber, Markus. Mineral Surfaces as Agents of Environmental Proteolysis: Mechanisms and Controls. United States: N. p., 2019. Web. doi:10.1021/acs.est.8b05583.
Chacon, Stephany S., Reardon, Patrick N., Burgess, Christopher J., Purvine, Samuel, Chu, Rosalie K., Clauss, Therese R., Walter, Eric, Myrold, David D., Washton, Nancy, & Kleber, Markus. Mineral Surfaces as Agents of Environmental Proteolysis: Mechanisms and Controls. United States. doi:10.1021/acs.est.8b05583.
Chacon, Stephany S., Reardon, Patrick N., Burgess, Christopher J., Purvine, Samuel, Chu, Rosalie K., Clauss, Therese R., Walter, Eric, Myrold, David D., Washton, Nancy, and Kleber, Markus. Fri . "Mineral Surfaces as Agents of Environmental Proteolysis: Mechanisms and Controls". United States. doi:10.1021/acs.est.8b05583.
@article{osti_1503671,
title = {Mineral Surfaces as Agents of Environmental Proteolysis: Mechanisms and Controls},
author = {Chacon, Stephany S. and Reardon, Patrick N. and Burgess, Christopher J. and Purvine, Samuel and Chu, Rosalie K. and Clauss, Therese R. and Walter, Eric and Myrold, David D. and Washton, Nancy and Kleber, Markus},
abstractNote = {Here, we investigated the extent to which contact with mineral surfaces affected the molecular integrity of a model protein, with an emphasis on identifying the mechanisms (hydrolysis, oxidation) and conditions leading to protein alteration. To this end, we studied the ability of four mineral surface archetypes (negatively charged, positively charged, neutral, redox-active) to abiotically fragment a well-characterized protein (GB1) as a function of pH and contact time. GB1 was exposed to the soil minerals montmorillonite, goethite, kaolinite, and birnessite at pH 5 and pH 7 for 1, 8, 24, and 168 h and the supernatant was screened for peptide fragments using Tandem Mass Spectrometry. To distinguish between products of oxidative and hydrolytic cleavage, we combined results from the SEQUEST algorithm, which identifies protein fragments that were cleaved hydrolytically, with the output of a deconvolution algorithm (DECON-Routine) designed to identify oxidation fragments. All four minerals were able to induce protein cleavage. Manganese oxide was effective at both hydrolytic and oxidative cleavage. The fact that phyllosilicates—which are not redox active—induced oxidative cleavage indicates that surfaces acted as catalysts and not as reactants. Our results extend previous observations of proteolytic capabilities in soil minerals to the groups of phyllosilicates and Fe-oxides. We identified structural regions of the protein with particularly high susceptibility to cleavage (loops and β strands) as well as regions that were entirely unaffected (α helix).},
doi = {10.1021/acs.est.8b05583},
journal = {Environmental Science and Technology},
number = 6,
volume = 53,
place = {United States},
year = {2019},
month = {2}
}

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This content will become publicly available on February 15, 2020
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