Open Access. Powered by Scholars. Published by Universities.®

Biochemistry, Biophysics, and Structural Biology Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 22 of 22

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Mutational Analysis Of Aspergillus Awamori Glucoamylase Selectivity To Improve Glucose Yield , Hsuan-Liang Liu Jan 1998

Mutational Analysis Of Aspergillus Awamori Glucoamylase Selectivity To Improve Glucose Yield , Hsuan-Liang Liu

Retrospective Theses and Dissertations

Three single mutations, Lys108→Arg, Lys108→Met and Tyr312→Trp, and one insertional mutation, 322-314 Loop, in Aspergillus awamori glucoamylase were constructed and tested along with four previously constructed thermostable mutations: Asn20→Cys/Ala27→Cys (SS), Ser30→Pro, Gly137→Ala, and Ser436→Pro, and one previously made thermosensitive mutation, Ala27→Pro, for their selectivity by high-concentration glucose condensation and maltodextrin hydrolysis reactions. Lys108 is important in substrate binding during maltooligosaccharide hydrolysis. Both SS and 311-314 Loop mutant GAs successfully decrease isomaltose formation rate and thus increase peak glucose yield. Tyr312→Trp GA helps to form a tighter hydrogen bond network ...


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 ...


The Role Of Domain E In The Activity Of Bacillus Macerans Cyclodextrin Glucanotransferase , Hai-Yin Chang Jan 1997

The Role Of Domain E In The Activity Of Bacillus Macerans Cyclodextrin Glucanotransferase , Hai-Yin Chang

Retrospective Theses and Dissertations

Cyclodextrin glucanotransferase (CGT) folds into five domains A, B, C, D and E. Domain E has the ability to bind starch and cyclodextrins (CDs) and is considered the starch-binding domain of CGT. The role of domain E in the catalysis of Bacillus macerans cyclodextrin glucanotransferase was investigated by constructing five CGT mutants. The truncated CGT (CGT[delta]E) mutant was constructed by deleting domain E, and the chimeric CGT (CGT-SBD) by replacing domain E with the starch-binding domain (SBD) of Aspergillus glucoamylase I. The modified CGT (CGT+6) was constructed by inserting a six-amino-acid pseudo linker between domains D and ...


Protein Engineering Of The Ph Dependence And Substrate Specificity Of Glucoamylase From Aspergillus Awamori , Tsuei-Yun Fang Jan 1997

Protein Engineering Of The Ph Dependence And Substrate Specificity Of Glucoamylase From Aspergillus Awamori , Tsuei-Yun Fang

Retrospective Theses and Dissertations

Glucoamylase (EC 3.2.1.3) (GA), an enzyme that catalyzes the release of [beta]-D-glucose from the nonreducing ends of starch and related oligo- and polysaccharides, is widely used in industry to produce high-glucose syrups. Site-directed mutagenesis was used to construct mutations to obtain mutant enzymes with industrially desired alterations in pH dependence and substrate specificity;An increased pH optimum for GA would be industrially desirable so that it could be used in process conditions more similar to that of other enzymatic steps in starch processing. Five mutations were designed to remove or weaken the hydrogen bond between Ser411 ...


Effects Of Ear Developmental Temperature On Fine Structure Of Maize Starch , Ting-Jang Lu Jan 1995

Effects Of Ear Developmental Temperature On Fine Structure Of Maize Starch , Ting-Jang Lu

Retrospective Theses and Dissertations

Two genetically unrelated normal dent maize inbreds, ICI63 and ICI92, with different heterotic backgrounds were used for studying environmental temperature effects on grain yield and quality. These two maize inbreds are used in commercially available hybrids and are proprietary to ICI Seeds. The maize inbreds were grown in a greenhouse to control the growing condition of the plants. After 14 days post-pollination, the ears were wrapped in temperature control devices set at 25 or 35∘ C during the grain-filling period. Grain yield, kernel weight, and kernel density were less for ears developing at 35∘ C than for those at 25 ...


Characterization And Application Of Porcine Liver Aldehyde Oxidase In The Removal Of Off-Flavors From Soy Proteins , Peeyush Maheshwari Jan 1995

Characterization And Application Of Porcine Liver Aldehyde Oxidase In The Removal Of Off-Flavors From Soy Proteins , Peeyush Maheshwari

Retrospective Theses and Dissertations

Two enzyme forms (PAO-I and PAO-II) of porcine liver aldehyde oxidase (aldehyde: oxygen oxidoreductase, EC 1.2.3.1) were purified to homogeneity using affinity chromatography. The heat treatment and ammonium sulfate fractionation steps resulted only in a partial purification. Both enzyme forms, PAO-I and PAO-II, have similar pIs of 5.8 and molecular weight of 262,000 and 255,000 daltons, respectively;The two enzyme forms exhibited different substrate specificities. Compared to PAO-II, PAO-I showed higher affinity for the medium-chain aldehydes (pentanal and hexanal) which are mainly responsible for the greeny and beany off-flavor of soybean products. The PAO-I ...


The Relationship Between The Calpain Enzyme System And The Postmortem Degradation Of Selected Myofibrillar Proteins , Elisabeth Jane Huff Lonergan Jan 1995

The Relationship Between The Calpain Enzyme System And The Postmortem Degradation Of Selected Myofibrillar Proteins , Elisabeth Jane Huff Lonergan

Retrospective Theses and Dissertations

The protease [mu]-calpain degrades the myofibrillar proteins titin, nebulin, filamin, desmin and troponin-T. Titin and nebulin have been reported to be affected by sample preparation. This study showed that there was little difference in the rate of degradation of the intact forms due to sample preparation (whole muscle preparations vs. purified myofibrils). The postmortem degradation of titin, nebulin, filamin, desmin, and troponin-T was monitored using SDS-PAGE and Western blotting techniques at 0, 1, 3, 7, 14, 28, and 56 days postmortem. Postmortem aged samples with lower shear force values exhibited faster degradation of the five myofibrillar proteins. Similar degradation ...


Site-Directed Mutagenesis To Enhance Thermostability Of Aspergillus Awamori Glucoamylase Expressed In Saccharomyces Cerevisiae , Hsiu-Mei Chen Jan 1993

Site-Directed Mutagenesis To Enhance Thermostability Of Aspergillus Awamori Glucoamylase Expressed In Saccharomyces Cerevisiae , Hsiu-Mei Chen

Retrospective Theses and Dissertations

A program of site-directed mutagenesis was undertaken to enhance thermostability of Aspergillus awamori glucoamylase. Nine mutations were designed, based on three different irreversible thermoinactivation mechanisms of glucoamylase. Each mutant was expressed in Saccharomyces cerevisiae, and their production, activities, and irreversible thermoinactivation rates were determined;First, the Asn182 and Asn395 residues were each replaced with Gln to reduce their deamidation rates. Asn395, but not Asn182, was N-glycosylated by yeast. Deletion of the N-glycan linked to Asn395 did not affect specific activity, but greatly decreased enzyme secretion and thermostability. Replacement of Asn182 by Gln did not change glucoamylase specific activity or thermostability ...


Acceptor Reactions And Mechanism Of Leuconostoc Mesenteroides B-512fm Dextransucrase , Aziz Tanriseven Jan 1993

Acceptor Reactions And Mechanism Of Leuconostoc Mesenteroides B-512fm Dextransucrase , Aziz Tanriseven

Retrospective Theses and Dissertations

Although Hanes-Woolf plot showed that methyl [alpha]-D-glucopyranoside was an apparent competitive inhibitor for dextransucrase, a Michaelis-Menten plot using methyl [alpha]-D-glucopyranoside in the presence of high concentration of sucrose showed that it was not a real competitive inhibitor. We have also found that methyl 6-deoxy-[alpha]-D-glucopyranoside and methyl 6-deoxy-6-fluoro-[alpha]-D-glucopyranoside were weak inhibitors, whereas the corresponding sucrose analogues 6-deoxysucrose and 6-deoxy-6-fluorosucrose are very potent inhibitors for dextransucrase. From these findings, it is concluded that the acceptor, methyl [alpha]-D-glucopyranoside, does not compete with sucrose for the sucrose binding-sites and it binds at a separate acceptor binding-site;A ...


Characterization Of The Starch-Binding Domain Of Aspergillus Glucoamylase Produced In Escherichia Coli , Ann R. Kusnadi Jan 1992

Characterization Of The Starch-Binding Domain Of Aspergillus Glucoamylase Produced In Escherichia Coli , Ann R. Kusnadi

Retrospective Theses and Dissertations

We have produced intracellularly 8.8, 3.4, and 3.2 mg/l [beta]-galactosidase and two [beta]-galactosidase fusion proteins containing amino acids 498-616 (BSB119), and amino acids 537-616 (BSB80) of Aspergillus glucoamylase I, respectively. The fusion proteins suffered from extensive proteolytic degradation resulting in a mixture of full-size fusion proteins and [beta]-galactosidase. Granular starch adsorption study of these purified [beta]-galactosidase fusion proteins showed that BSB119 had the strongest interaction with granular starch;To overcome the proteolytic degradation problem associated with the [beta]-galactosidase fusion proteins, we have fused three different lengths of starch-binding fragments encoding amino ...


Binding Of 14c-Heptanal To Soy Proteins Glycinin And [Beta]-Conglycinin , Sharma Marini Cooray Jan 1992

Binding Of 14c-Heptanal To Soy Proteins Glycinin And [Beta]-Conglycinin , Sharma Marini Cooray

Retrospective Theses and Dissertations

Soy proteins have excellent functional properties that can be utilized in improving the quality of processed foods. The off-flavor problem in soy proteins caused by short chain aliphatic aldehydes interacting with them makes these products unacceptable to the consumers. Upto date the complete removal of the off-flavor from soy products has not been reached. Complete reversibility of flavor binding to soy proteins was assumed in studying ligand binding to soy proteins, which is contradictory to the fact that removal of the off-flavor from soy proteins is almost not feasible. In order to test the validity of this assumption it was ...


Isolation And Determination Of Nutritional Factors In Food And Fodder Yeast, Robert Lee Smith Jan 1954

Isolation And Determination Of Nutritional Factors In Food And Fodder Yeast, Robert Lee Smith

Retrospective Theses and Dissertations

No abstract provided.


Terminal Amino Acid Residues Appearing During The Proteolysis Of Lysozyme , Thomas Lighthall Hurst Jan 1953

Terminal Amino Acid Residues Appearing During The Proteolysis Of Lysozyme , Thomas Lighthall Hurst

Retrospective Theses and Dissertations

No abstract provided.


Decarboxylase Activity Of Pseudomonas Species Found In Dairy Products , Joseph E. Edmondson Jan 1953

Decarboxylase Activity Of Pseudomonas Species Found In Dairy Products , Joseph E. Edmondson

Retrospective Theses and Dissertations

No abstract provided.


The Lipase Of Pseudomonas Fragi , Selim Abdulkadir Nashif Jan 1951

The Lipase Of Pseudomonas Fragi , Selim Abdulkadir Nashif

Retrospective Theses and Dissertations

No abstract provided.


The Distribution Of Certain Amino Acids In The Soluble Nitrogen Fraction Of Milk Cultures Of Streptococcus Lactis , Max Eugene Morgan Jan 1948

The Distribution Of Certain Amino Acids In The Soluble Nitrogen Fraction Of Milk Cultures Of Streptococcus Lactis , Max Eugene Morgan

Retrospective Theses and Dissertations

No abstract provided.


The Effect Of Variation In Mashing Procedures Upon The Alcoholic Fermentation Of Corn , Frank Benjamin Folckemer Jan 1943

The Effect Of Variation In Mashing Procedures Upon The Alcoholic Fermentation Of Corn , Frank Benjamin Folckemer

Retrospective Theses and Dissertations

No abstract provided.


Fermentative Utilization Of Cassava , Julian Banzon Jan 1940

Fermentative Utilization Of Cassava , Julian Banzon

Retrospective Theses and Dissertations

No abstract provided.


Some Factors Affecting The Time Of Solution Of Dextrose , Benjamin Franklin Buchanan Jan 1938

Some Factors Affecting The Time Of Solution Of Dextrose , Benjamin Franklin Buchanan

Retrospective Theses and Dissertations

No abstract provided.


The Action Of Lipolytic Bacteria On Some Simple Tri-Glycerides And Some Natural Fats , Mervyn Avery Collins Jan 1933

The Action Of Lipolytic Bacteria On Some Simple Tri-Glycerides And Some Natural Fats , Mervyn Avery Collins

Retrospective Theses and Dissertations

No abstract provided.


The Volatile Acids Formed From Citric And Lactic Acids By Streptococcus Citrovorus And Streptococcus Paracitrovorus , Michael B. Michaelian Jan 1931

The Volatile Acids Formed From Citric And Lactic Acids By Streptococcus Citrovorus And Streptococcus Paracitrovorus , Michael B. Michaelian

Retrospective Theses and Dissertations

No abstract provided.


Chemical Sterilization With Alkalies, James Roger Hall Jan 1930

Chemical Sterilization With Alkalies, James Roger Hall

Retrospective Theses and Dissertations

No abstract provided.