Grantee Research Project Results

2004 Progress Report: Linear Polymer Chain and Bioengineered Chelators for Metals Remediation

EPA Grant Number: R831276C009
Subproject: this is subproject number 009 , established and managed by the Center Director under grant CR831276
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: UT Center for Infrastructure Modeling and Management
Center Director: Hodges, Ben R.
Title: Linear Polymer Chain and Bioengineered Chelators for Metals Remediation
Investigators: Holcombe, James , Browning, Karen
Institution: The University of Texas at Austin
EPA Project Officer: Aja, Hayley
Project Period: December 1, 2003 through November 30, 2004
Project Period Covered by this Report: December 1, 2003 through November 30, 2004
Project Amount: Refer to main center abstract for funding details.
RFA: Gulf Coast Hazardous Substance Research Center (Lamar University) (1996) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Targeted Research

Objective:

The objectives of this research project are to: (1) develop novel metal chelators employing synthetic, short chain peptides; and (2) characterize these materials both with regard to their selectivity, binding strength, and ease of reclamation.

Progress Summary:

The goal of this project was to design an optimized (i.e., strong binding and selective) chelator using short chain peptides. These then could be used in metal remediation. Such chemical architecture allows for optimal flexibility in design of ligands along a polymer chain and ultimately can be incorporated in phytoremediation through incorporation of these peptides into a cell by genome alterations. As immobilized chelators, these systems allow for strong binding and easy release because of tertiary structure alteration during reclamation. Additionally, the systems are not environmentally friendly when disposed of because they are simple peptides.

During Year 1, we showed that polyaspartate (PLAsp) immobilized on controlled pore glass (CPG) and polyglutamate (PLGlu) had very similar metal binding characteristics despite the extra methylene group in the carboxylate side chain of PLGlu. These polymers are unlike nature’s metal binding proteins that have a predetermined tertiary structure for metal binding. As a result, in a protein, the substitution of an asp for a glu, or vice versa, may cause a significant change in the metal binding capabilities. Both polymers possess a metal binding trend of Cu²⁺ >> Pb²⁺ > Ni²⁺ » Cd²⁺ > Co²⁺ > Mn²⁺ >> Na⁺, with a maximum capacity for Cu²⁺ at approximately 14 mmol/g CPG. Mixed metal studies clearly demonstrated the improved selectivity of Cu²⁺ and Pb²⁺ over Cd²⁺ and Ni²⁺ for both polymers by showing that Cu²⁺ and Pb²⁺ were able to displace bound Cd²⁺ and Ni²⁺ from the columns. In general, these polymers behaved very similarly in all of the studies conducted and should be equally suitable for trace metal preconcentration and remediation from natural and industrial waste streams.

In another study, we attempted to investigate how glycine “spacer” residues affect the metal binding capabilities of a polyaspartic acid chain using a combinatorial approach. A combinatorial library of peptide sequences ranging from 20 aspartic acids to 20 glycines, and all of the sequences in between, was developed by the split and pool synthesis method. The library was screened for its Cu binding capabilities by micro-X-ray fluorescence (MXRF), a high throughput elemental analysis technique. This was done in a collaborative study with Los Alamos National Laboratories. Successful library beads were determined by direct comparison to PLAsp beads. Attempts were made to sequence the beads that exhibited the greatest Cu binding by Edman degradation. Ultimately, if these sequences had been elucidated, a polymer of the “ideal” sequence would have been synthesized, in bulk, and immobilized onto CPG and analyzed according to its metal binding capabilities.

Unfortunately, after the analysis of the library, Edman degradation suggested that the integrity of the purchased bead set was poor (i.e., the presence of a single sequence on a single bead did not exist). Considerable time was extended to determine if the source of the problem was in the bead preparation or bead analysis. At present, the results seemed to indicate that the problem occurred in the Edman degradation procedure because of the presence of glycine residues.

Although this experiment was not successful in establishing the relationship between the presence of glycine residues in a polyaspartic acid chain and Cu binding ability, the results were encouraging. Several beads were identified that had a significantly greater Cu binding ability than PLAsp. In addition, it has been shown that the current methodology utilizing combinatorial chemistry, MXRF, and Edman degradation to investigate the metal binding capabilities of multiple sequences simultaneously was successful. Improving the integrity of the sequencing methodology is an ongoing project as the potential for using combinatorial libraries and rapid screening should provide large returns for targeting chelation systems that can be used in specific clean-up applications.

Future Activities:

More emphasis will be placed on combinatorial libraries for isolation of optimally functional peptide chelators. This approach will permit efficient optimized selection of a sequence that would be not only selective for a particular metal(s) but also could select against particular innocuous metals (e.g., Na, Ca).

We plan to use the information gained in the development of these experimental protocols to synthesize binding sequences that are selective for uranium and arsenic using combinatorial chemistry. We also plan to take these peptides and develop them into trace metal sensor using fluorescence resonance energy transfer (FRET).

Journal Articles on this Report : 3 Displayed | Download in RIS Format

Publications Views

Other subproject views:	All 7 publications	3 publications in selected types	All 3 journal articles
Other center views:	All 64 publications	19 publications in selected types	All 18 journal articles

Publications

Type	Citation	Sub Project	Document Sources
Journal Article	Malachowski L, Holcombe JA. Immobilized poly-L-histidine for chelation of metal cations and metal oxyanions. Analytica Chimica Acta 2003;495(1-2):151-163.	CR831276 (Final) R831276C009 (2004)	Full-text: ScienceDirect - Full Text HTML Exit Abstract: ScienceDirect - Abstract Exit Other: ScienceDirect - Full Text PDF Exit
Journal Article	Malachowski L, Holcombe JA. Comparison of immobilized poly-L-aspartic acid and poly-L-glutamic acid for chelation of metal cations. Analytica Chimica Acta 2004;517(1-2):187-193.	CR831276 (Final) R831276C009 (2004)	Full-text: ScienceDirect - Full Text HTML Exit Abstract: ScienceDirect - Abstract Exit Other: ScienceDirect - Full Text PDF Exit
Journal Article	Malachowski L, Stair JL, Holcombe JA. Immobilized peptides/amino acids on solid supports for metal remediation. Pure and Applied Chemistry 2004;76(4):777-787.	CR831276 (Final) R831276C009 (2004)	Full-text: IUPAC - Full Text PDF Exit Abstract: IUPAC - Abstract Exit

Supplemental Keywords:

metal remediation, chelation, peptide chelators, waste, ecological risk assessment, environmental engineering, hazardous waste, advanced treatment technologies, bioremediation, contaminated waste sites, groundwater contamination, petroleum contaminants, hydrocarbon,, RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Waste, TREATMENT/CONTROL, Water, POLLUTANTS/TOXICS, Remediation, Contaminated Sediments, Environmental Chemistry, Technology, Chemicals, Hazardous Waste, Hazardous, Environmental Engineering, hazardous waste treatment, contaminated sediment, remediation technologies, bio-engineering, contaminated soil, linear polymer chain, metal chelation, biotechnology, groundwater remediation, metal extraction, contaminated groundwater, biotransformation, hazardous wate, combinatorial chemistry, metal wastes, heavy metal contamination, metal contamination, metal removal

Relevant Websites:

http://research.cm.utexas.edu/jholcombe/contents.html Exit
http://dept.lamar.edu/gchsrc/ Exit

Progress and Final Reports:

Original Abstract

Final

Main Center Abstract and Reports:

CR831276    UT Center for Infrastructure Modeling and Management

Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R831276C001 DNAPL Source Control by Reductive Dechlorination with Fe(II)
R831276C002 Arsenic Removal and Stabilization with Synthesized Pyrite
R831276C003 A Large-Scale Experimental Investigation of the Impact of Ethanol on Groundwater Contamination
R831276C004 Visible-Light-Responsive Titania Modified with Aerogel/Ferroelectric Optical Materials for VOC Oxidation
R831276C005 Development of a Microwave-Induced On-Site Regeneration Technology for Advancing the Control of Mercury and VOC Emissions Employing Activated Carbon
R831276C006 Pollution Prevention through Functionality Tracking and Property Integration
R831276C007 Compact Nephelometer System for On-Line Monitoring of Particulate Matter Emissions
R831276C008 Effect of Pitting Corrosion Promoters on the Treatment of Waters Contaminated with a Nitroaromatic Compounds Using Integrated Reductive/Oxidative Processes
R831276C009 Linear Polymer Chain and Bioengineered Chelators for Metals Remediation
R831276C010 Treatment of Perchlorate Contaminated Water Using a Combined Biotic/Abiotic Process
R831276C011 Rapid Determination of Microbial Pathways for Pollutant Degradation
R831276C012 Simulations of the Emission, Transport, Chemistry and Deposition of Atmospheric Mercury in the Upper Gulf Coast Region
R831276C013 Reduction of Environmental Impact and Improvement of Intrinsic Security in Unsteady-state
R831276C014 Integrated Chemical Complex and Cogeneration Analysis System: Greenhouse Gas Management and Pollution Prevention Solutions
R831276C015 Improved Combustion Catalysts for NOx Emission Reduction
R831276C016 A Large-Scale Experimental Investigation of the Impact of Ethanol on Groundwater Contamination
R831276C017 Minimization of Hazardous Ion-Exchange Brine Waste by Biological Treatment of Perchlorate and Nitrate to Allow Brine Recycle
R831276C018 Integrated Chemical Complex and Cogeneration Analysis System: Greenhouse Gas Management and Pollution Prevention Solutions