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Chemical engineering

Biochemistry, Biophysics, and Structural Biology

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Full-Text Articles in Engineering

Recovery Of Recombinant Proteins From Transgenic Plants: Strategies In Implementation And Optimization , Todd J. Menkhaus Jan 2002

Recovery Of Recombinant Proteins From Transgenic Plants: Strategies In Implementation And Optimization , Todd J. Menkhaus

Retrospective Theses and Dissertations

Strategies to optimize the recovery of recombinant proteins from plant hosts have been investigated. The use of different crops, different product molecules, and different separation techniques was studied to suggest modes of operation that reduce the overall processing cost for obtaining purified recombinant proteins from plants.;Polyelectrolyte precipitation of beta-glucuronidase (GUS), an acidic model protein, with polyethyleneimine (PEI), a polycatonic polymer, from the extracts of canola, corn germ, soybean, and pea met with varying degrees of success. Precipitation from canola required the least amount of PEI and was capable of providing the highest enrichment. In contrast, soy and pea allowed ...


Enhancing Chromatographic Separations Of Recombinant Proteins From Canola Extracts By Genetic Design And Characterization Of Protein Binding Regions , Chenming Zhang Jan 1999

Enhancing Chromatographic Separations Of Recombinant Proteins From Canola Extracts By Genetic Design And Characterization Of Protein Binding Regions , Chenming Zhang

Retrospective Theses and Dissertations

Canola was studied as an alternative source to traditional microbial systems as a recombinant protein production host. Various chromatographic methods were used in this work to systematically characterize the native canola protein elution profiles, and different genetically engineered proteins were selected to explore the opportunities presented for effective protein recovery;Native canola protein was eluted into two major peaks in linear salt gradient elution on cation-exchange chromatography. T4 lysozyme and its mutants, by both point mutation and fusion, were used as model proteins to investigate the charge effect on protein elution. It was found that the single mutant T4 lysozyme ...


Computational Studies Of Glucoamylase Selectivity , Pedro Maldonado Coutinho Jan 1996

Computational Studies Of Glucoamylase Selectivity , Pedro Maldonado Coutinho

Retrospective Theses and Dissertations

Glucoamylase (GA) is an industrial enzyme involved in the production of glucose and fructose syrups from starch. Exhibiting a large spectrum of selectivities, GAs are able to cleave glucose from the nonreducing ends of [alpha]-(1,4) glycosidic bonds of maltooligosaccharide chains and the [alpha]-(1,6) bonds initiating their branches. The high temperatures and glucose concentrations occurring in saccharification lead to the formation of condensation products, reducing the overall glucose yield. Modified versions of Aspergillus GA that better satisfy industrial requirements are desirable. To achieve this, a structure-based multisequence alignment of the primary sequences of the catalytic domains, linkers ...


Enhancement Of Polyelectrolyte Precipitation Through The Genetic Fusion Of Charged Polypeptides To Enzymes , Mark Quinn Niederauer Jan 1993

Enhancement Of Polyelectrolyte Precipitation Through The Genetic Fusion Of Charged Polypeptides To Enzymes , Mark Quinn Niederauer

Retrospective Theses and Dissertations

The focus of this work was to investigate the enhancement of polyelectrolyte precipitation through the genetic alteration of the target protein. The dissertation is divided into three primary chapters: a literature review of precipitation techniques which display high selectivity, experimental work including the characterization and precipitation of the fusion enzymes, and modeling of the precipitation process;The literature review of selective precipitation techniques focuses on those techniques for which relatively high purifications can be achieved. The techniques include precipitation with polyelectrolytes, affinity ligands, metal ions, and protein-binding dyes. Topics discussed include the mechanisms of selectivity and precipitation, degrees of purification ...


Characterization Of Substrate Binding And Catalytic Mechanisms Of An Endoxylanase, Amylosucrase, And Porcine Pancreatic Alpha-Amylase , Bernard Yi Tao Jan 1988

Characterization Of Substrate Binding And Catalytic Mechanisms Of An Endoxylanase, Amylosucrase, And Porcine Pancreatic Alpha-Amylase , Bernard Yi Tao

Retrospective Theses and Dissertations

The subsite affinity map of an endo-(1 → 4)-[beta]-xylanase produced by Aspergillus niger has been determined by using linear, [superscript]3H-reducing-end-labeled xylooligosaccharides ranging in length from xylotriose through xylooctaose. No evidence of multiple attack or of condensation and transxylosylation reactions was found. Bond cleavage frequencies were highest near the reducing end of short substrates, with the locus of highest frequencies moving towards the middle of larger substrates. This endoxylanase has five major subsites, with the catalytic site located between the third and fourth subsites, counting from the non-reducing end of the bound substrate. The subsite to the non-reducing ...


Mutagenesis Of The Active Site Of Glucoamylase From Aspergillus Awamori , Michael R. Sierks Jan 1988

Mutagenesis Of The Active Site Of Glucoamylase From Aspergillus Awamori , Michael R. Sierks

Retrospective Theses and Dissertations

The Aspergillus awamori glucoamylase gene was modified by cassette mutagenesis, and eleven mutated enzymes were expressed by Saccharomyces cerevisiae;Four mutations were constructed to change the essential Trp 120 residue in subsite 4 to Tyr, Phe, His, and Leu. All the mutations bound maltose (G2) and isomaltose (iG2) more strongly than wild-type glucoamylase. A subsite map of the Tyr 120 mutation showed significantly higher affinities for D-glucosyl residues in subsites 1 and 2, suggesting an interaction of Trp 120 with residues located there;Three carboxylic acid residues in the active site, Asp 176, Glu 179, and Glu 180, were mutated ...