Biological and Chemical Physics Commons^™

Nadph-Cytochrome P450 Oxidoreductase: Extraction Of The Full-Length Protein And Methyl-Trosy Nmr Of The Soluble Mutants, Sara Ali Jamal Arafeh

Master's Theses (2009 -)

NADPH-cytochrome p450 oxidoreductase (CYPOR) is a membrane-bound protein in living cells. CYPOR delivers electrons to cytochrome p450 proteins (CYPs) to catalyze metabolism of drugs and synthesis of steroids. Extraction and solubilization of CYPOR from the membrane is typically done with the TritonX-100 detergent. The amount of the solubilized protein by this detergent, however, remains relatively low to structurally analyze CYPOR with NMR spectroscopy. The goal of the first project in this thesis was to optimize the amount of the extracted CYPOR from the E. coli membrane using various detergents and additives. To this aim, non-ionic detergents with variable hydrophobicity (TritonX-100, …

Functional And Structural Studies Of Cytochromes P450 By Resonance Raman Spectroscopy, Yilin Liu

Dissertations (1934 -)

Cytochrome P450 is a broad class of heme monooxygenase enzymes which catalyze various oxidative transformations. There are two main kinds of mammalian P450s: steroidogenic and drug metabolizing P450s. The first project involves a steroidogenic P450, CYP17A1, occupying a central role in the biosynthesis of steroid hormones. It catalyzes hydroxylation reaction on pregnenolone and progesterone, generating 17OH-pregnenolone and 17OH-progesterone, presumably utilizing a “Compound I” species. However, these hydroxylated products can be further processed in a second oxidative cycle to cleave the C17–C20 bond to form dehydroepiandrosterone or androstenedione, respectively, a crucial step in androgen production. Interestingly, it is well known that …

Region-Of-Interest Material Decomposition From Truncated Energy-Resolved Ct, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose: Energy-resolved CT using photon-counting detectors has the potential to provide improved material decomposition compared to dual-kVp approaches. However, available photon-counting detectors are susceptible to pulse-pileup artifacts, especially at the periphery of the field of view (FOV) where the object attenuation is low compared to the center of the FOV. Pulse pileup may be avoided by imaging a region-of-interest (ROI) where the dynamic range is expected to be limited. This work investigated performing material decomposition and reconstructing ROI basis images from truncated energy-resolved data.

Methods: A method is proposed to reconstructimages of basis functions primarily contained within the ROI, such …

Synthesis, Molecular Structure, And Reactivity Of Dinuclear Copper(Ii) Complexes With Carboxylate-Rich Coordination Environments, Richard C. Holz, John M. Bradshaw, Brian Bennett

Physics Faculty Research and Publications

The dinucleating ligand N,N‘-(2-hydroxy-5-methyl-1,3-xylylene)bis(N-(carboxymethyl)glycine) (CH₃HXTA) has been used to synthesize the dinuclear Cu(II) bis(pyridine) complex Na[Cu₂(CH₃HXTA)(Py)₂]·1.5(1,4-dioxane) (Na(1)):  triclinic space group P1̄ (a = 12.550(3) Å, b = 13.413(3) Å, c = 13.540(4) Å, α = 117.12(2)°, β = 104.70 (2)°, and γ = 92.13(2)°). The structure shows two distinct distorted square pyramidal Cu(II) centers with each Cu(II) ion bound by two carboxylate oxygen atoms, one amine nitrogen atom, a phenolate oxygen atom, and one pyridine nitrogen atom. The Cu--Cu separation is 3.531 Å, …

Spectroscopically Distinct Cobalt(Ii) Sites In Heterodimetallic Forms Of The Aminopeptidase From Aeromonas Proteolytica:  Characterization Of Substrate Binding, Brian Bennett, Richard C. Holz

Physics Faculty Research and Publications

The Co(II)Zn(II)- and Zn(II)Co(II)-substituted derivatives of the aminopeptidase from Aeromonas proteolytica (AAP) were probed by EPR spectroscopy. EPR spectra of the high-spin S = ³/₂ Co(II) ions in [CoZn(AAP)] and [ZnCo(AAP)] indicated that each metal binding site provides a spectroscopically distinct signature. For [CoZn(AAP)], subtraction of EPR spectra recorded at pH 7.5 and 10 revealed that two species were present and that the relative contributions to each of the experimental spectra were pH-dependent. The first EPR species, predominant at lower pH values, was simulated as a relatively featureless axial signal with g_eff values of 2.20, 3.92, and …

Epr Studies On The Mono- And Dicobalt(Ii)-Substituted Forms Of The Aminopeptidase From Aeromonas Proteolytica. Insight Into The Catalytic Mechanism Of Dinuclear Hydrolases, Brian Bennett, Richard C. Holz

Physics Faculty Research and Publications

The structure and function of the prototypical dinuclear hydrolase, namely, the aminopeptidase from Aeromonas proteolytica (AAP), was probed by EPR spectroscopy of the mono- and dicobalt(II)-substituted derivatives. A new systematic protocol for the interpretation of Co(II) EPR spectra is described and the S = ³/₂ spin states of the Co(II)-substituted forms of the enzyme have been characterized. This protocol allows the simulation of line shape using theoretically allowed g_eff values corresponding to an isotropic g_real value. In addition, the gross distortion of EPR spectra of high-spin S = ³/₂ Co(II) ions has been investigated, …

Evidence Favoring Molybdenum−Carbon Bond Formation In Xanthine Oxidase Action: 17O- And 13C-Endor And Kinetic Studies, Barry D. Howes, Robert C. Bray, Raymond L. Richards, Nigel A. Turner, Brian Bennett, David J. Lowe

Physics Faculty Research and Publications

The reaction mechanism of the molybdoenzyme xanthine oxidase has been further investigated by ¹³C and ¹⁷O ENDOR of molybdenum(V) species and by kinetic studies of exchange of oxygen isotopes. Three EPR signal-giving species were studied:  (i) Very Rapid, a transient intermediate in substrate turnover, (ii) Inhibited, the product of an inhibitory side reaction with aldehyde substrates, and (iii) Alloxanthine, a species formed by reaction of reduced enzyme with the inhibitor, alloxanthine. The Very Rapid signal was developed either with [8-¹³C]xanthine or with 2-oxo-6-methylpurine using enzyme equilibrated with [¹⁷O]H₂O. The Inhibited signal was …

Calibration Of An X-Ray Unit As To Effective Wave-Lengths By Comparing Absorption Coefficients, Jerome James Woyci

Bachelors’ Theses

The purpose of this paper is to determine by the mass absorption coefficients of various substances, namely, aluminum, copper and iron, the effective wave-length of an X-ray beam which passes through particular thicknesses of the above materials. Since an X-ray tube does not emit a monochromatic wavelength but emits heterogeneous wave-lengths, we had to use a comparative method in order to obtain the desired results. It happens that the mass coefficient of absorption of carbon does not vary appreciably with an increase or decrease in wavelength, hence, we can use carbon as our standard or material to which we can …

The Construction And Use Of The Barrett Camera, Theresa Pauline Radermacher

Bachelors’ Theses

The study of the crystal structure of metals under various conditions of strain is at the present time the object of a great deal of scientific endeavor. A greater knowledge of the condition of strained crystals will be a tremendous aid in the future development of metallic construction for one can then predict the effect of any type of strain on a metal by the reaction of the individual crystals to that particular strain. It is the purpose of this paper to describe the construction and use of the Barrett camera which is used in experiments of this kind.

A Study Of Melting Points Of Various Binary And Tertiary Mixtures Of Waxes, Neil G. Goodrich

Bachelors’ Theses

The work undertaken in this thesis was done in cooperation with Joseph Sevenich and is a continuation of the work done by George Hable, Leonard Veranth and Lewis Wrangell. In this present work, the melting points of various trinary mixtures of waxes was studied, also the reliability of the method used in the determinations, and the effect of heat upon the mixtures. Graphs are used in the thesis in order to present a clearer picture of the work done and the results obtained.

A Study Of Melting Points Of Various Binary Mixtures Of Waxes, George John Hable

Bachelors’ Theses

Waxes, chemically speaking, are a class of esters which consist of mono- or di-hidric alcohols united with the higher fatty acids. These waxes contain free fatty acids, free alcohols and hydrocarbons. A considerable quantity of free cerotic acid (C26H52O2) myricyl palmitate (C16H31O2. C31H63), and high melting point hydrocarbons are found in beeswax. The acids that occur in waxes appear to have an even number of carbon atoms. Paraffine, ceresine, and ozokerite are really not waxes at all according to the chemical conception. The latter two are esters of glycerine united with higher fatty acids.