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University of Arkansas, Fayetteville

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Articles 181 - 207 of 207

Full-Text Articles in Biochemistry

Influence On Proline Upon The Folding And Geometry Of A Model Transmembrane Peptide, Rachel Thomas Jan 2009

Influence On Proline Upon The Folding And Geometry Of A Model Transmembrane Peptide, Rachel Thomas

Inquiry: The University of Arkansas Undergraduate Research Journal

The orientations, geometries and lipid interactions of designed transmembrane (TM) peptides have attracted significant experimental and theoretical interest. Because the amino acid proline will introduce a known discontinuity into an alpha-helix, it is important to measure the extent of helix kinking caused by a single proline within an isolated TM helical domain. For this purpose, acetyl-GWWLALALAP10ALALALWWA-ethanolamide was synthesized, and pairs of deuterated alanines were included by using 60-100% deuterated fluorenylmethoxycarbonyl-L-alanine ifmoc-d4-L-Ala) at selected sequence positions. Solid-state deuterium fH) magnetic resonance spectra from oriented, hydrated samples (1140, peptide/lipid; using several lipids) reveal signals from many of the alanine backbone Ca deuterons …

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Letter From The Dean, Lalit Verma Jan 2009

Letter From The Dean, Lalit Verma

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

No abstract provided.

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Computational Study Of A Novel Dinuclear Metal Complex, Dragos Seghete Jan 2005

Computational Study Of A Novel Dinuclear Metal Complex, Dragos Seghete

Inquiry: The University of Arkansas Undergraduate Research Journal

The first compound containing an M-H-M was recently reported by Vicic et al. With recent availability of large computational resources, molecular modeling has become a reliable tool for confirming experimental results. The novel dinuclear Ni complex [( dippm)2Ni2Br2]( 0 -H) was investigated in this work from a theoretical perspective. Full geometry optimization was carried on the dinuclear Ni complex at the DFT/B3LYP with the 6-31G* basis set. The result verifies the linear Ni-H-Ni bond. Two different starting structures that converged to the same geometry confirm that a global minimum was reached. The computed structure differs from the experimentally determined one …

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Rec12 (Spo11) Recominase Of Fission Yeast Promotes A Backup, Distributive Pathway For Chromosome Segregation In Meiosis I, Wallace D. Sharif, Mari K. Davidson, Wayne P. Wahls Jan 2003

Rec12 (Spo11) Recominase Of Fission Yeast Promotes A Backup, Distributive Pathway For Chromosome Segregation In Meiosis I, Wallace D. Sharif, Mari K. Davidson, Wayne P. Wahls

Journal of the Arkansas Academy of Science

We studied the relationship between recombination and segregation in the fission yeast Schizosaccharomyces pombe. In meiosis, chromosomes undergo two rounds of segregation to produce haploid meiotic products. Crossover meiotic ecombination (chiasmata) promotes chromosome segregation during meiosis I; achiasmatic chromosomes often suffer on disjunction in meiosis I. Recl2 protein is a topoisomerase IIortholog that introduces double-strand DNA breaks that nitiate recombination. The red2 null (deletion) and active site (Y98F) mutants lack recombination and crossovers, and onsequently suffer meiosis I nondisjunction. However, null mutants chromosomes segregate to opposite poles more frequently than predicted. Thus, fission yeast has a backup, "distributive segregation" pathway …

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Properties Of Modified Tryptophans In A Membrane- Spanning Channel, Erin M. Scherer Jan 2002

Properties Of Modified Tryptophans In A Membrane- Spanning Channel, Erin M. Scherer

Inquiry: The University of Arkansas Undergraduate Research Journal

An emerging concept in biology assigns the amino acid tryptophan specific roles at the membrane/water interface that help to determine the conformation and biological function of membrane-spanning proteins. Previous studies involving the antibiotic model system gramicidin A (gA) have illustrated the importance of the indole ring of tryptophan (Trp) in anchoring proteins to a bilayer membrane and promoting ionic currents. To further investigate these phenomena, derivatives of Trp that have lost hydrogen-bonding ability (1-methyl-Trp ), have an altered dipole moment (7-aza-Trp), or both (1-methyl-7-azaTrp) were chosen for incorporation into gA. Gramicidin analogues that incorporate these modified Trps were then analyzed …

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Development Of A Yeast Biosensor Strain For The Identification Of Genotoxic Compounds, Robin M. Reed Jan 2002

Development Of A Yeast Biosensor Strain For The Identification Of Genotoxic Compounds, Robin M. Reed

Inquiry: The University of Arkansas Undergraduate Research Journal

Advances in combinatorial chemistry have provided the pharmaceutical industry with innumerable lead compounds that could potentially serve as therapeutic agents. One of the challenges in the further development of such compounds is to rapidly, yet inexpensively, distinguish those that have undesirable effects such as genotoxicity. Thus, a simple biological assay that would permit the identification of potential DNA mutagens, and be adaptable to high-throughput technologies would be cost effective in screening such lead compounds. The current methods use the Ames and SOS tests involving prokaryotic organisms, while systems that utilize mammalian cell culture and/or animal testing are time-consuming and expensive. …

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Molecular Orbital Studies Of Nitrosyl Metalloporphyrin Complexes, John P. Graham, Genevive Brown Jan 2001

Molecular Orbital Studies Of Nitrosyl Metalloporphyrin Complexes, John P. Graham, Genevive Brown

Journal of the Arkansas Academy of Science

Molecular orbital calculations are applied to the study of the structure and bonding of nitrosyl metalloporphyrin complexes. The Fenske-Hall approximate molecular orbital method and the Amsterdam Density Functional (ADF) method are used. The calculations provide qualitative and quantitative explanations for the observed structural differences between the nitrosyl porphyrin complexes ofiron, manganese, and cobalt. It is proposed that the energy of the highest occupied molecular orbital (HOMO) of these complexes is primarily responsible for the observed structural differences. The interaction between the nitrosyl ligand and metal dz2 orbital results in an antibonding orbital that is occupied in the complexes of Fe …

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Analysis Of Phytoestrogens By High Performance Liquid Chromatography, Anne A. Grippo, Yan Xie, Benjamin L. Rougeau, William V. Wyatt Jan 1999

Analysis Of Phytoestrogens By High Performance Liquid Chromatography, Anne A. Grippo, Yan Xie, Benjamin L. Rougeau, William V. Wyatt

Journal of the Arkansas Academy of Science

Phytoestrogens are biochemicals synthesized in plants which mimic steroidal estrogen activity in mammals. Analysis of these compounds in the legumes which produce them and in body fluids is important to the study of their physiological effects. High pressure liquid chromatography (HPLC) has been found to be an efficient and sensitive method of identification and quantitation of isoflavonoids, one class of phytoestrogen. Here we report the separation of three isoflavonoids, biochanin A, genistein and daidzein using an HPLC system with a Cg reverse phase column and a linear gradient mobile phase containing acetonitrile and acetic acid/water (10/90, v/v) over 60 minutes. …

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Effective, Reliable, Inexpensive Cryofixation Device, Lawrence A. Mink, Roger A. Buchanan Jan 1994

Effective, Reliable, Inexpensive Cryofixation Device, Lawrence A. Mink, Roger A. Buchanan

Journal of the Arkansas Academy of Science

No abstract provided.

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Thermal Decomposition Studies Of Selected Transition Metal Polysulfide Complexes. Ii. Effect Of Atmosphere On Decomposition, Benjamin Rougeau, Mark Draganjac Jan 1994

Thermal Decomposition Studies Of Selected Transition Metal Polysulfide Complexes. Ii. Effect Of Atmosphere On Decomposition, Benjamin Rougeau, Mark Draganjac

Journal of the Arkansas Academy of Science

Initial studies involved the thermal decomposition profile of five polysulfide complexes in air up to 550 °C. Since our first report to the Academy in 1990, we have obtained the capability to run samples up to 1500°C under various gases. Thermal Gravimetric Analysis (TGA) and Differential Thermal Analysis (DTA)of a series of transition metal polysulfide complexes are presented. Compounds analyzed included Cp2TiS5 ,MoS9 2",MoOS8 2", Zn(S x ) 2", Cd(S x ) 2-, Fe2S122 - and NiS82.

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Conformational And Circular Dichroism Studies On N-Acetyl-L-Prolyl-D-Alanyl-Methylamide, S. Ramaprasad Jan 1990

Conformational And Circular Dichroism Studies On N-Acetyl-L-Prolyl-D-Alanyl-Methylamide, S. Ramaprasad

Journal of the Arkansas Academy of Science

The compact ordered conformations of the molecule N-Acteyl-L-Prolyl-D-Alanyl-Methylamide have been studied by semiempirical energy calculations in vacuum and circular dichroism (CD) in solution. The presence of ordered structure has been observed in hydrogen bond promoting solvents like trifluoroethanol by CD studies. In hydrogen bond breaking solvents, like trifluoroacetic acid (TFA), significant fraction of the ordered conformers probably assume extended conformation without intramolecular hydrogen bonds and perhaps are in equilibrium with the fraction of compact ordered structures. The trend observed in going from nonpolar to polar solvent is also compatible with the previous NMR studies in solution. The semiempirical energy calculations …

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Mermithid Nematodes: Sem Observations Comparing Hexamethyldisilazane And Critical Point Drying Methods, William R. Bowen, Christopher C. Hemann, Arthur A. Johnson, Barry H. Good Jan 1990

Mermithid Nematodes: Sem Observations Comparing Hexamethyldisilazane And Critical Point Drying Methods, William R. Bowen, Christopher C. Hemann, Arthur A. Johnson, Barry H. Good

Journal of the Arkansas Academy of Science

Morphological features of mermithid nematodes (Mermithidae) were studied with scanning electron microscopy, using hexamethyldisilazane-air drying in comparison with critical point drying via liquid carbon dioxide. Although general morphologic preservation of both HMDS-dried and CP-dried specimens was similar, structural features of the complex cuticle and internal organization were more easily resolved at higher magnifications in the HMDS-dried nematodes. These features include the superficial cuticular annulations, the fibrillar inner cuticle and peg-like microtrabeculae. The previously undescribed microtrabeculae are of special interest since they may facilitate an interaction of the mermithid (and perhaps nameatodes in general) musculature with its body wall that, at …

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Spectrophotomatic Assay For The Enzyme Catalyzed Reaction Of 4-Nitroquinoline 1-Oxide With Glutathione, J. Steven Stanley, Ann M. Benson Jan 1987

Spectrophotomatic Assay For The Enzyme Catalyzed Reaction Of 4-Nitroquinoline 1-Oxide With Glutathione, J. Steven Stanley, Ann M. Benson

Journal of the Arkansas Academy of Science

4-Nitroquinoline 1-oxide (4NQO(is a toxic and carcinogenic compound that has been reported to be subject to conjugation with glutathione (GSH). This reaction may proceed non-enzymatically or be catalyzed by GSH transferases. The non-enzymatic rate for this reaction has been reported to be very high. The purposes of this investigation were to develop a spectrophotometric assay for the reaction of4NQO with GSH and to determine whether the rate for the enzyme catalyzed reaction was significant relative to the non-enzymatic reaction. The absorbance spectrum of 4NQO in phosphate buffer exhibited a maximum at 365 nm. Reaction of 4NQO with GSH was accompanied …

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Effects Of Growth Temperatures On The Fatty Acid Composition Of Isolated Chloroplasts From Two Species Differing In Heat Sensitivity, Roy Z. Gehring, Glenn W. Todd Jan 1985

Effects Of Growth Temperatures On The Fatty Acid Composition Of Isolated Chloroplasts From Two Species Differing In Heat Sensitivity, Roy Z. Gehring, Glenn W. Todd

Journal of the Arkansas Academy of Science

Lipid analyses of chloroplasts isolated from wheat (Triticum aestivum L. cv. Arthur) and milo (Sorghum bicolor cv. Funk's hybrid 522) suggest no major heat effect on lipid class distribution. Assuming milo is more heat tolerant than wheat and that increased saturated/unsaturated fatty acid values increase thermal stability, changes in sulfoquinovosyldiglyceride (SL) appear to be more important than phosphatidylglycerol (PG) in conferring thermal stability to isolated chloroplasts.

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Concanavalin A-Binding Enzymes Of Crotalus Scutulatus Scutulatus Venom, Michael W. Hinson, C. K. Childs, Bob D. Johnson, Dewey H. Sifford Jan 1985

Concanavalin A-Binding Enzymes Of Crotalus Scutulatus Scutulatus Venom, Michael W. Hinson, C. K. Childs, Bob D. Johnson, Dewey H. Sifford

Journal of the Arkansas Academy of Science

Crotalus scutulatus scutulatus crude venom was separated into two fractions by Concanavalin A Sepharose 4B affinity chromatography. The proteins binding to Con A exhibited phosphomonoesterase (orthophosphoric monoester phosphohydrolase EC 3.1.3.2), phosphodiesterase, 5'-nucleotidase (5'-ribonucleotide phosphohydrolase EC 3.1.3.5), phospholipase A(phosphatidate 2-acylhydrolase EC 3.1.1 .4), hyaluronidase (hyaluronate glycanohydrolase EC 3.2.1 d), N-benzoyl-L-arginine ethyl esterase, p-toluenesulfonyl-L-arginine methyl esterase, L-amino acid oxidase (L-amino acid: 02 oxidoreductase [deaminating] EC 1.4.3.2), and caseinolytic activities. Thrombin-like and NAD nucleosidase (5'-ribonucleotide phosphohydrolase EC 3.1.3.5) activities were not observed. The crude venom and the fraction containing the glycoproteins which bound to Con A were fractionated by DEAE Sephadex A-50 ion …

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Methemoglobin Reduction In The Presence Of Various Concentrations Of Oxyhemoglobin, Ali Mansouri Jan 1985

Methemoglobin Reduction In The Presence Of Various Concentrations Of Oxyhemoglobin, Ali Mansouri

Journal of the Arkansas Academy of Science

Methemoglobin reduction in human red blood cell is governed by many factors, one of which is the concentration of oxyhemoglobin. Experiments were conducted to determine the inhibition of methemoglobin reduction by oxyhemoglobin under concentrations approaching those in the red cell. Hemoglobin, methemoglobin reductase and cytochrome b₅ were prepared by routine protein purification methods. Methemoglobin reduction was carried out at 37° C in spectrophotometer. It is shown that methemoglobin concentration variation (at least when it is above 1 mM) does not change the reduction rate. Whereas, the ratio of methemoglobin to oxyhemoglobin determines the rate of methemoglobin reduction when all other …

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Demonstration Of A Heat-Stable Cyclic Gmp Phosphodiesterase In The Medium Of Physarum Flavicomum, Thomas J. Lynch, Mark S. Ross Jan 1985

Demonstration Of A Heat-Stable Cyclic Gmp Phosphodiesterase In The Medium Of Physarum Flavicomum, Thomas J. Lynch, Mark S. Ross

Journal of the Arkansas Academy of Science

No abstract provided.

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Neutral Sugars In Selected Pit Viper, Elapid, Lizard And Scorpion Venoms, Ahmed El-Sherif, Paul D. Gwinup, Bob D. Johnson, Dewey H. Sifford Jan 1983

Neutral Sugars In Selected Pit Viper, Elapid, Lizard And Scorpion Venoms, Ahmed El-Sherif, Paul D. Gwinup, Bob D. Johnson, Dewey H. Sifford

Journal of the Arkansas Academy of Science

No abstract provided.

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Enzymes In Heloderma Horridum Venom, S. A. Murphy, Bob D. Johnson, D. H. Sifford Jan 1976

Enzymes In Heloderma Horridum Venom, S. A. Murphy, Bob D. Johnson, D. H. Sifford

Journal of the Arkansas Academy of Science

A mixture of venom and saliva from the lizard Heloderma horridum was analyzed for esterase, phosphomonoesterase, phosphodiesterase, 5'nucleotidase, and protease activities. Hydrolysis of N-benzoyl-L-arginine ethyl ester occurred at a pH optimum between pH 8.6 and 9.1 with a maximum activity of 452 units per mg per min. Hydrolysis of ptoluenesulfonyl-L-arginine methyl ester occurred at a pH optimum between pH 8.1 and 8.5 with a maximum of only 36 units per mg per min. One mg of the venom mixture liberated 9.3 μM of p nitrophenol from p-nitrophenyl phosphate per minute at an optimum pH between 8.2 and 8.3. Over a …

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Influence Of Dietary Fats And Carbohydrates On Lipid Metabolism In Male And Female Rats, Marjorie Ellen Fitch Jan 1976

Influence Of Dietary Fats And Carbohydrates On Lipid Metabolism In Male And Female Rats, Marjorie Ellen Fitch

Journal of the Arkansas Academy of Science

Effects of dietary fats and carbohydrates on lipid metabolism in rats were studied. Male and female 4-week-old rats were divided into 8 groups and fed 4 fat-carbohydrate combinations (beef tallow or safflower oil, each with either sucrose or rice starch). After 4 weeks, animals were killed by exsanguination through the abdominal aorta and livers were removed. Plasma and liver cholesterol and phospholipids were determined qualitatively and quantitatively. Liver moisture, protein, and lipid and the fatty acid composition of the total liver lipid were determined quantitatively. Variations in growth, food efficiency, and lipid metabolism, particularly as manifested by the fatty acid …

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Effect Of Estrogen And/Or Supplemental Substrates On Uterine Utilization Of Pyruvate For Lipid Synthesis, Julie W. Harris Jan 1976

Effect Of Estrogen And/Or Supplemental Substrates On Uterine Utilization Of Pyruvate For Lipid Synthesis, Julie W. Harris

Journal of the Arkansas Academy of Science

Precursor incorporation into uterine lipids was examined in vitro after estradiol-17ß administration in immature female rats. The effect of adding supplemental substrates, glucose or gluconate, to the incubation medium on the labeling pattern of pyruvate-3-¹⁴C into uterine lipids was studied. Presence of supplemental substrate in the medium enhanced the incorporation of pyruvate into uterine lipids after two hours of in vivo estrogen treatment. It is suggested that estrogen's acceleration of pyruvate incorporation into lipid may be due to a concomitant effect on glucose metabolism.

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Dietary Fat-Carbohydrate Combinations: Their Effects On Lipid Metabolism In Estrogen-Treated Rats, Beverly A. Clevidence Jan 1976

Dietary Fat-Carbohydrate Combinations: Their Effects On Lipid Metabolism In Estrogen-Treated Rats, Beverly A. Clevidence

Journal of the Arkansas Academy of Science

Female rats 4 weeks old were fed diets including beef tallow or safflower oil in combination with sucrose or rice starch. At 8 weeks of age, half the rats were orally administered 2 of estrogen (mestranol) in 5 μl of safflower oil and half were fed the vehicle only. After 10 to 14 days of estrogen treatment, rats were fasted and exsanguinated. Alterations were found in weight gain, liver weights, and levels of various lipids in plasma and liver. Most lipid levels were influenced by an interaction of mestranol with one of the dietary factors. No changes were observed in …

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Metabolic Responses Of White Rats To Glucose Or Fructose Fed With Two Safflower Oils Containing Different Proportions Of Fatty Acid, Paula Lynn Yates Jan 1969

Metabolic Responses Of White Rats To Glucose Or Fructose Fed With Two Safflower Oils Containing Different Proportions Of Fatty Acid, Paula Lynn Yates

Journal of the Arkansas Academy of Science

No abstract provided.

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Metabolic Changes Induced In Rats By Feeding Different Levels Of Galactose With Two Levels Of Corn Oil, Carolyn Qualls Sharp Jan 1967

Metabolic Changes Induced In Rats By Feeding Different Levels Of Galactose With Two Levels Of Corn Oil, Carolyn Qualls Sharp

Journal of the Arkansas Academy of Science

No abstract provided.

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Interrelationships Of Certain Metabolic Responses To Threonine Deficiency And To Various Dietary Carbohydrates In The White Rat, Elizabeth Bright Jan 1965

Interrelationships Of Certain Metabolic Responses To Threonine Deficiency And To Various Dietary Carbohydrates In The White Rat, Elizabeth Bright

Journal of the Arkansas Academy of Science

No abstract provided.

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Effects Of Saturated And Unsaturated Long Chain Fatty Acids On Various Components Of Lipid And Carbohydrate Metabolism, Joyce T. Burgess Jan 1965

Effects Of Saturated And Unsaturated Long Chain Fatty Acids On Various Components Of Lipid And Carbohydrate Metabolism, Joyce T. Burgess

Journal of the Arkansas Academy of Science

No abstract provided.

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Effect Of Dietary Galactose Vs. Glucose With Corn Oil And With Hydrogenated Coconut Oil On Various Metabolic Functions In Rats, Mabel R. Coleman, Catherine Carroll Jan 1965

Effect Of Dietary Galactose Vs. Glucose With Corn Oil And With Hydrogenated Coconut Oil On Various Metabolic Functions In Rats, Mabel R. Coleman, Catherine Carroll

Journal of the Arkansas Academy of Science

No abstract provided.

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