Biomedical subjects

Tonya L Peeples

Publications and source records attributed to Tonya L Peeples.

5 recordsLinked to original sources

PubMed2004

Purification of hyperthermophilic archaeal amylolytic enzyme (MJA1) using thermoseparating aqueous two-phase systems.

Purification of a recombinant, thermostable alpha-amylase (MJA1) from the hyperthermophile, Methanococcus jannaschii, was investigated in the ethylene oxide-propylene oxide random copolymer (PEO-PPO)/(NH(4))(2)SO(4), and poly(ethylene glycol) (PEG)/(NH(4))(2)SO(4) aqueous two-phase systems. MJA1 partitioned in the top polymer-rich phase, while the remainder of proteins partitioned in the bottom salt-rich phase. It was found that enzyme recovery of up to 90% with a purification factor of 3.31 was achieved using a single aqueous two-phase extraction step. In addition, the partition behavior of pure amyloglucosidase in polymer/salt aqueous two-phase systems was also evaluated. All of the studied enzymes partitioned unevenly in these polymer/salt systems. This work is the first reported application of thermoseparating polymer aqueous two-phase systems for the purification of extremophile enzymes.

Chromatography, Liquid↗

PubMed2002

Amylase partitioning and extractive bioconversion of starch using thermoseparating aqueous two-phase systems.

The effectiveness of thermoseparating polymer-based aqueous two-phase systems (ATPS) in the enzymatic hydrolysis of starch was investigated. In this work, the phase diagrams of PEO-PPO-2500/ammonium sulfate and PEO-PPO-2500/magnesium sulfate systems were determined at 25 degrees C. The partition behavior of pure alpha-amylase and amyloglucosidase in four ATPS, namely, PEO-PPO/(NH(4))(2)SO(4), PEO-PPO/MgSO(4), polyethylene glycol (PEG)/(NH(4))(2)SO(4), and PEG/MgSO(4), was evaluated. The effects of phase-forming component concentrations on the enzyme activity and partitioning were assessed. Partitioning of a recombinant, thermostable alpha-amylase (MJA1) from the hyperthermophile, Methanococcus jannaschii was also investigated. All of the studied enzymes partitioned unevenly in these polymer/salt systems. The PEO-PPO-2500/MgSO(4) system was extremely attractive for starch hydrolysis. Polymer-based starch hydrolysis experiments containing PEO-PPO-2500/MgSO(4) indicated that the use of ATPS had a significant effect on soluble starch hydrolysis. Batch starch hydrolysis experiments with PEO-PPO/salt two-phase systems resulted in higher production of maltose or glucose and exhibited remarkably faster hydrolysis. A 22% gain in maltose yield was obtained as a result of the increased productivity. This work is the first reported application of thermoseparating polymer ATPS in the processing of starches. These results reveal the potential for thermoseparating polymer-enhanced extractive bioconversion of starch as a practical technology.

Biotechnology↗

PubMed2002

Archaeal tetraether lipids: unique structures and applications.

The extremely stable biomolecules manufactured by organisms from extreme environments are of great scientific and engineering interest in the development of robust and stable industrial biocatalysts. Identification of molecules that impart stability under extremes will also have a profound impact on our understanding of cellular survival. This review discusses isolation and characterization of archaeal tetraethers as well as target technologies for tetraether lipid application. The isolation and characterization of archaeal tetraether lipids has led to some interesting applications improving on ester lipid technologies. Potential applications include novel lubricants, gene-delivery systems, monolayer lipid matrices for sensor devices, and protein stabilization. Following this review, patent abstracts and additional literature pertaining to the isolation, characterization, and application of archaeal membrane lipids are listed.

Archaea↗

PubMed1999

Role of multiple gene copies in particulate methane monooxygenase activity in the methane-oxidizing bacterium Methylococcus capsulatus Bath.

Genes for the subunits of particulate methane monooxygenase, PmoABC, have been sequenced from the gamma-proteobacterial methanotroph Methylococcus capsulatus Bath. M. capsulatus Bath contains two complete copies of pmoCAB, as well as a third copy of pmoC. The two pmoCAB regions were almost identical at the nucleotide sequence level, differing in only 13 positions in 3183 bp. At the amino acid level, each translated gene product contained only one differing residue in each copy. However, the pmoC3 sequence was more divergent from the two other pmoC copies at both the far N-terminus and far C-terminus. Chromosomal insertion mutations were generated in all seven genes. Null mutants could not be obtained for pmoC3, suggesting that it may play an essential role in growth on methane. Null mutants were obtained for pmoC1, pmoC2, pmoA1, pmoA2, pmoB1 and pmoB2. All of these mutants grew on methane, demonstrating that both gene copies were functional. Copy 1 mutants showed about two-thirds of the wild-type whole-cell methane oxidation rate, while copy 2 mutants showed only about one-third of the wild-type rate, indicating that both gene copies were necessary for wild-type particulate methane monooxygenase activity. It was not possible to obtain double null mutants that were defective in both pmo copies, which may indicate that some expression of pMMO is important for growth.

Amino Acid Sequence↗

PubMedDate not supplied

Screening extremophiles for bioconversion potentials.

A screening protocol was developed and implemented to evaluate extremophiles, in particular hyperthermophiles and thermoacidophiles, for their capacity to transform starch-based feedstocks to high-value organic acids and solvents. Screening results of 14 extremophiles showed promising growth and biotransformation potentials. In particular, Hyperthermus butylicus, Thermococcus litoralis, and Sulfolobus acidocaldarius were identified as producers of both organic acids and solvents under the screening protocol. The screening effort presented here represents an important step toward realization of biotransformation potentials of extremophiles, potentially improving upon biomass-based processes.

Archaea↗