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QD - Chemistry acquired during July 2016

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Basic elements of crystallography
Gonzalez Szwacki, Nevill
Singapore : Pan Stanford Publishing Pte Ltd, [2016]
Kresge QD905.2 .S99 2016

Electron transfer within conformationally flexible metalloproteins
Gu, Jie
"Structural flexibility is essential to protein function. Fluctuations in protein conformation could alter donor-acceptor electronic couplings and reduction potentials of redox proteins thus influencing electron transfer (ET) rates. However, experimental proof is limited. Herein, a systematic study of intramolecular ET is reported to investigate the role of protein dynamics on the ET reactivity in cytochrome (cyt) c. In the first study, flexibility of protein polypeptide chain around residues 52 and 67 is varied by perturbing the hydrogen-bonding network. Y67F mutation alters the ET pathway and leads to an increase in the Fe²⁺-to-Ru³⁺ ET rate constant. The additional N52I mutation, off the ET pathway, reverses the effect of Y67F, suggesting the dynamic cross-talk of the two sites. In the second work, substituting the sixth ligand Met to the heme iron by His, Ala and SeMet in Ru-labeled cyt c variants have been found to affect the intramolecular ET rate constants. Besides major influences on the reduction potentials, axial-ligand substitutions also appear to affect the electronic couplings and the reorganization energies of cyt c. In the third work, cyt c has been converted to the molten-globular (MG) state, in which the protein loses the tertiary structure but keeps the secondary structure mostly intact. ET reactions between the heme iron and a ruthenium complex labeled at five different locations on the protein surface show similar rate constants, independent of the dominant ET pathways. We propose that folding of the 71-85 Ω loop is required for efficient Fe²⁺-to-Ru³⁺ ET reactions and becomes a rate-limiting "gating" step in the reaction. Kinetics of the [Omega] loop rearrangement probed by CO dissociation and contact dynamics in the denatured state are in support of this hypothesis. The last study is designed to probe the alkaline conformational change that significantly alters cyt c ET reactivity. Multiple spectroscopic characterizations of cyt c T49V mutant have revealed a Lys-ligated conformer at neutral pH. The pK[subscript a] value associated with the Met-to-Lys conversion in the sixth ligand is almost three-pH units lower than that of WT. The effects arise from the change in the protein scaffold mediated by the hydrogen-bonding network."
Rauner D.C. Hist Thesis QD47.5.N43 D3 2016gu

Principles of modern chemistry : student solutions manual
Oxtoby, David W
Boston, MA : Cengage Learning, ©2016
Kresge QD31.3 .O887 2016b

Micro- and nanostructured polymer systems : from synthesis to applications
edited by Sabu Thomas, PhD, Robert A. Shanks, PhD, and Jithin Joy
Waretown, NJ : Apple Academic Press, [2016]
"This book focuses on the recent trends in micro- and nano-structured polymer systems, particularly natural polymers, biopolymers, biomaterials, and their composites, blends, and IPNs. This valuable volume covers the occurrence, synthesis, isolation, production, properties and applications, modification, as well as the relevant analysis techniques to reveal the structures and properties of polymer systems. Biobased polymer blends and composites occupy a unique position in the dynamic world of new biomaterials. The growing environmental awareness of the society has become an major factor in recent decades- is playing a major role in the advancement of biomaterials technology. Natural polymers have attained their cutting-edge technology through various platforms, and this book presents a multitude of information about them. Topics include biopolymer-synthetic systems; nanomaterial-polymer structures; multi-characterization techniques; polymer blends and composites; polymer gels, polyelectrolytes; and many other interesting aspects of interests to researchers This book will be valuable to scientists, engineers, industrialists, researchers and other specialists in a variety of disciplines, both academic and industrial."--
Kresge QD381 .M47 2016

Conducting polymers : bioinspired intelligent materials and devices
Otero, Toribio Fernández
Cambridge : Royal Society Of Chemistry, 2016
Conducting polymers are organic, conjugated materials that offer high electrical conductivity through doping by oxidation and a wide range of unique electromechanical and electrochromic characteristics. These properties can be reversibly tuned through electrochemical reactions, making this class of materials good biomimetic models and ideal candidates for the development of novel flexible and transparent sensing devices. This book comprehensively summarises the current and future applications of conducting polymers, with chapters focusing on electrosynthesis strategies, theoretical models for composition dependent allosteric and structural changes, composition dependent biomimetic properties, novel biomimetic devices and future developments of zoomorphic and anthropomorphic tools. -- Back cover.
Kresge QD382.C66 O84 2016

Thermodynamic studies of copper binding to azurin : development and application of a novel method to determine the reduction potential and reduction thermodynamics of metalloproteins
Croteau, Molly L
"Cupredoxins, such as stellacyanin, plastocyanin, amicyanin, rusticyanin, and azurin perform electron transfer (ET) reactions with partner protein(s) in the cell. The role of the redox cofactor in these proteins is played by a copper ion, which becomes oxidized or reduced in order to donate or receive one electron. These blue copper proteins share a similar copper coordination site with equatorial ligands consisting of two histidine imidazoles and one cysteine thiolate, as well as one or two weaker axial ligands, but their reduction potential ([epsilon]°) spans the range from +190 mV to +390 mV, with rusticyanin at an incredible +680 mV. It is still not well understood how Nature tunes these and other metalloprotein reduction potentials, when the cofactor and coordination site are similar. To provide insight into this tunability, the enthalpy ([Delta]H), entropy ([Delta]S), and free energy ([Delta]G°) of copper, both in its Cu²⁺ and Cu⁺ oxidation states, binding to apo-azurin have been determined by isothermal titration calorimetry (ITC). Cu²⁺ binding is enthalpically unfavorable and entropically favorable, which indicates that the coordination of Cu²⁺ to apo-azurin reorganizes hydrogen bonds and water molecules that are at the surface of the hydrophobic metal site, resulting in the favorable entropy. Cu⁺ binding is both enthalpically and entropically favorable, which is expected due to the entatic state of the metal site which is imposed by the protein structure that prefers Cu⁺. In comparison to one another, Cu²⁺ is more entropically favorable, but more enthalpically unfavorable than Cu⁺. Since the metal site of azurin prefers the +1 oxidation state, there is less solvent reorganization and greater favorable bond formation upon Cu⁺ coordination than Cu²⁺. A new method to determine the reduction potential and contributing reduction thermodynamics for metalloproteins has been developed and validated with azurin, and is called reduction coordination thermodynamics (RCT). The thermodynamic parameters for both Cu²⁺ and Cu⁺ binding to azurin, along with those for the reduction of aqueous copper were used in a thermodynamic cycle to quantify the reduction enthalpy ([Delta]H[subscript epsilon][subscript]°), free energy ([Delta]G°[subscript epsilon][subscript]°), and subsequently the reduction entropy ([Delta]S[subscript epsilon][subscript]°) and reduction potential ([epsilon]°). Others have determined these values with electrochemical methods, but these require a range of temperatures to obtain [Delta]H[subscript epsilon][subscript]° and [Delta]S[subscript epsilon][subscript]°, and there are assumptions that are not accurate or ignored for aqueous proteins. The reduction thermodynamic values obtained for azurin with the RCT method corroborate with the literature values determined with electrochemical methods. The RCT method was then applied to three azurin variants with unknown [Delta]H[subscript epsilon][subscript]° and [Delta]S[subscript epsilon][subscript]° values. The variants consisted of mutations to the 1[superscript]st coordination sphere, the 2[superscript]nd coordination sphere, and a combination of both, and were: F114P, F114P/M121Q, and N47S/F114N/M121L. The resulting [epsilon]° values were comparable to directly-measured electrochemical [epsilon]° values, and [Delta]H[subscript epsilon][subscript]° and [Delta]S[subscript epsilon][subscript]° were reported for the first time along with the contributing [Delta]H and [Delta]S values for each Cu²⁺ and Cu⁺ binding.
Rauner D.C. Hist Thesis QD47.5.N43 D3 2016cro

Bonding, structure and solid-state chemistry
Ladd, M. F. C
Oxford : Oxford University Press, 2016
Kresge QD478 .L3 2016

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