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Zoology and genetics

Biochemistry

Articles 1 - 6 of 6

Full-Text Articles in Molecular Biology

Characterization Of Two Novel Spindle Matrix Proteins In Drosophila, Chromator And Megator , Dong Wang Jan 2003

Characterization Of Two Novel Spindle Matrix Proteins In Drosophila, Chromator And Megator , Dong Wang

Retrospective Theses and Dissertations

A spindle matrix has been proposed to help organize and stabilize microtubules during mitosis. This concept has gained new interest due to the identification of Skeletor as a potential component of the spindle matrix. Skeletor is associated with chromosomes during interphase but reorganizes into a spindle-like structure during early prophase before the nuclear envelope breaks down and microtubules enter the nucleus. The Skeletor spindle extends from pole to pole during metaphase coaligning with the microtubule spindle and persists even after nocodazole treatment dissembles the microtubules. These features make Skeletor an ideal candidate as a spindle matrix protein.;In this study ...


Genetic And Biochemical Analysis Of Aspergillus Awamori Glucoamylase Thermostability , Martin John Allen Jan 1997

Genetic And Biochemical Analysis Of Aspergillus Awamori Glucoamylase Thermostability , Martin John Allen

Retrospective Theses and Dissertations

Aspergillus awamori glucoamylase (GA) is an enzyme involved in industrial corn starch processing. Genetic and biochemical approaches were used to study the mechanisms governing GA thermostability. Three proline substitution (Xaa → Pro) mutations were constructed that were predicted to increase the enzyme's stability by decreasing its conformational entropy of unfolding. When expressed in Saccharomyces cerevisiae Ser30 → Pro increased, Asp345 → Pro did not alter and Glu408 → Pro greatly decreased GA stability as measured by resistance to irreversible thermoinactivation relative to the wild-type enzyme. The Ser30 → Pro mutation was combined with other previously identified stabilizing mutations to examine whether combining such mutations ...


Genetic Construction And Biochemical Analysis Of Thermostability Mutants Of Glucoamylase From Aspergillus Awamori , Yuxing Li Jan 1996

Genetic Construction And Biochemical Analysis Of Thermostability Mutants Of Glucoamylase From Aspergillus Awamori , Yuxing Li

Retrospective Theses and Dissertations

To study the molecular basis of Aspergillus awamori glucoamylase (GA) thermostability, eighteen mutants were constructed by site-directed mutagenesis and expressed in Saccharomyces cerevisiae based on thermostability theories. Four lysine residues, K61, K279, K352 and K404, were replaced with arginine, with all but K404 well exposed to the solvent and far away from the enzyme activity site. Mutations K61F/D65E and H254W/E326Q were made to fill a packing void around the inner set of six [alpha]-helices of GA and to displace water molecules inside the void. Five residues (A27, A393, A435, Ser436 and Ser460) were replaced with proline. Two ...


G-Wires: The Growth And Characterization Of A G4-Dna Nanostructure , Thomas Cosgrove Marsh Jan 1994

G-Wires: The Growth And Characterization Of A G4-Dna Nanostructure , Thomas Cosgrove Marsh

Retrospective Theses and Dissertations

Guanine-rich sequences are vital components in the genomes of many organisms. For example, G-rich sequences are found in telomeres, fragile X locus, promoters, IgG switch regions, recombinational hot spots and the HIV RNA dimerization domain. The functions of these G-rich sequences rely in part on guanine self-recognition. G-rich sequences can adopt a quadruple helical conformation in the presence of specific monovalent and divalent metal cations which are also required for maintaining the quadruplex stability. The structural basis of the quadruplex is a cyclic Hoogsteen hydrogen bonded guanine tetrad known as the G-quartet. Sequences capable of forming G-quartets are classified as ...


Characterization Of Dna-Binding Proteins That Recognize The Replication Origin Of The Rrna Genes Of Tetrahymena Thermophila , Angela Rae Umthun Jan 1993

Characterization Of Dna-Binding Proteins That Recognize The Replication Origin Of The Rrna Genes Of Tetrahymena Thermophila , Angela Rae Umthun

Retrospective Theses and Dissertations

Proteins that bind to specific sequences in replication origins have been shown to be important components of both prokaryotic and eukaryotic DNA replication systems. An origin of DNA replication is located within the 5[superscript]' non-transcribed spacer region of the rRNA genes (rDNA) of Tetrahymena thermophila. Previous work has shown that several cis-acting mutations responsible for rDNA replication defects lie in upstream repeats of a transcriptional promoter element, the Type I repeat;Using FE(II)EDTA cleavage footprinting and gel-mobility shift assays, I identified and characterized two distinct DNA-binding activities that interact with the Type I repeat. One of these ...


Deletion Analysis Of The Starch Binding Domain From Aspergillus Glucoamylase , Luojing Chen Jan 1992

Deletion Analysis Of The Starch Binding Domain From Aspergillus Glucoamylase , Luojing Chen

Retrospective Theses and Dissertations

Glucoamylase (GA) from Aspergillus (EC 3.2.1.3) exists in two forms: GAI (amino acids 1-616) and GAII (amino acids 1-512). GAII is identical to GAI but lacks the C-terminal region (amino acids 513-616). While both forms of glucoamylase are able to digest soluble starch, only GAI has the ability to bind to and therefore hydrolyze native starch granules. To further examine the location of the starch binding domain at the C-terminus of GAI and to determine how many amino acid residues of GAI are required for starch binding, six [beta]-galactosidase fusion proteins were constructed. Affinity purified fusion ...