CRITICAL REVIEWS: SPECTROSCOPIC STUDIES ON PALLADIUM (II)-COMPLEXES WITH XANTHINE AND ITS DERIVATIVES AT NORMAL AND HIGH EXTERNAL PRESSURE

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A critical reviews on molecular spectroscopic work on the palladium (II) complexes with xanthine, caffeine, theobromine, and theophyline at normal and high external pressure is presented. The methods for high external pressure measurement with the aid of Diamond Anvil Cell and Raman Measurements are also reported

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Long distance electron-transfer mechanism in peptidylglycine alpha-hydroxylating monooxygenase: a perfect fitting for a water bridge.

Aurélien de la Lande, Sergio Martí, Olivier Parisel … (2007)

The active sites of copper enzymes have been the subject of many theoretical and experimental investigations from a number of years. Such studies have embraced topics devoted to the modeling of the first coordination sphere at the metallic cations up to the development of biomimetic, or bioinspired, catalytic systems. At least from the theoretical viewpoint, fewer efforts have been dedicated to elucidate how the two copper cations act concertedly in noncoupled dicopper enzymes such as peptidylglycine alpha-hydroxylating monooxygenase (PHM) and dopamine beta-monooxygenase (DbetaM). In these metalloenzymes, an electronic transfer is assumed between the two distant copper cations (11 A). Recent experimental results suggest that this transfer occurs through water molecules, a phenomenon which has been theoretically evidenced to be of high efficiency in the case of cytochrome b5 (Science, 2005, 310, 1311). In the present contribution dedicated to PHM, we overpass the common theoretical approaches dedicated to the electronic and geometrical structures of sites CuM or CuH restricted to their first coordination spheres and aim at directly comparing theoretical results to the experimentally measured activity of the PHM enzyme. To achieve this goal, molecular dynamics simulations were performed on wild-type and various mutants of PHM. More precisely, we provide an estimate of the electron-transfer efficiency between the CuM and CuH sites by means of such molecular dynamics simulations coupled to Marcus theory joined to the Beratan model to approximate the required coupling matrix elements. The theoretical results are compared to the kinetics measurements performed on wild and mutated PHM. The present work, the dynamic aspects of which are essential, accounts for the experimental results issued from mutagenesis. It supports the conclusion that an electronic transfer can occur between two copper(I) sites along a bridge involving a set of hydrogen and chemical bonds. Residue Gln170 is evidenced to be the keystone of this water-mediated pathway.

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Effects of aging on numbers, sizes and conduction velocities of myelinated and unmyelinated fibers of the pelvic nerve in rats.

Hitomi Nakayama, Koichi Noda, Harumi Hotta … (1998)

The effects of aging on the conduction velocities, numbers and sizes of the myelinated and unmyelinated fibers of the pelvic nerve in Wistar rats, aged 3-9 and 30-37 months were examined using electrophysiological and ultrastructural techniques. The myelinated fibers did not show significant age-related changes in the maximum conduction velocities (9.7 +/- 1.1 m/s in adult vs. 11.0 +/- 1.5 m/s in aged rats), the number of fibers (662 +/- 27 vs. 625 +/- 56) and distribution of fiber diameters. In aged rats, the unmyelinated fibers did not show a significant change in maximum conduction velocity (1.5 +/- 0.1 m/s vs. 1.5 +/- 0.1 m/s), but showed a significant decrease in the number of fibers (4133 +/- 114 vs. 3113 +/- 456), specifically of fibers smaller than 0.7 microm in diameter. It is concluded that myelinated fibers of the pelvic nerve in rats preserve their conduction ability and fiber population during aging, but unmyelinated fibers, particularly fibers with smaller diameters decrease in number. Unmyelinated fibers with larger diameters maintain their conduction ability and numbers with aging.

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Sympathetic and parasympathetic neuromuscular junctions in the guinea-pig sino-atrial node.

Julia K Choate, Megan Klemm, G.D.S. Hirst (1993)

The structure and organization of cholinergic and adrenergic varicosities in the sino-atrial node of the guinea-pig heart was determined by electron microscopy. When random sections of tissue were examined, some varicosities were found in close proximity (less than 90 nm) to a muscle cell, while others appeared to be some distance (greater than 90 nm) from the nearest muscle cell. When the organization of individual varicosities and their relationships with nearby cardiac muscle cells were determined by examining serial sections of tissue, it was found that most varicosities which lost all or part of their Schwann cell wrap formed close appositions with one or more cardiac muscle cells. At the regions of close apposition, the neuromuscular clefts were filled with a single layer of basal lamina, giving neuromuscular separations of about 80 nm. Although evidence of pre-synaptic or post-synaptic thickenings was not found, there was an accumulation of synaptic vesicles towards the regions of close apposition. These observations are discussed in relation to the idea that in a number of different tissues, most autonomic varicosities which lose part of their Schwann cell wrap, form organized neuromuscular junctions and that these junctions may be the sites of neuromuscular transmission.

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Author and article information

Contributors

Brij B. Tewari: Role: ND

Journal

Journal ID (publisher-id): rbq

Title: Revista Boliviana de Química

Abbreviated Title: Rev. Bol. Quim

Publisher: Universidad Mayor de San Andrés (La Paz, La Paz, Bolivia )

ISSN (Electronic): 0250-5460

Publication date (Print and electronic): 2013

Volume: 30

Issue: 2

Pages: 122-130

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[01] Georgetown orgnameUniversity of Guyana orgdiv1Faculty of Natural Sciences orgdiv2Department of Chemistry Guyana brijtew@ 123456yahoo.com

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Publisher ID: S0250-54602013000200003

SO-VID: c4b3dc8e-6dd5-4f4f-8ff1-d300f9ecc351

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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

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Date received : 02 October 2013

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Figures: 0, Tables: 0, Equations: 0, References: 109, Pages: 9

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SciELO Bolivia

Keywords: Spectroscopic studies,palladium (II) complex,xanthine,caffeine,theobromine,theophylline,diamond anvil cell,Raman measurements

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Keywords: Spectroscopic studies, palladium (II) complex, xanthine, caffeine, theobromine, theophylline, diamond anvil cell, Raman measurements

Translated title: CRITICAL REVIEWS: SPECTROSCOPIC STUDIES ON PALLADIUM (II)-COMPLEXES WITH XANTHINE AND ITS DERIVATIVES AT NORMAL AND HIGH EXTERNAL PRESSURE

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SciELO Bolivia

Most cited references 122

Long distance electron-transfer mechanism in peptidylglycine alpha-hydroxylating monooxygenase: a perfect fitting for a water bridge.

Effects of aging on numbers, sizes and conduction velocities of myelinated and unmyelinated fibers of the pelvic nerve in rats.

Sympathetic and parasympathetic neuromuscular junctions in the guinea-pig sino-atrial node.

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