Insight into externally bound 5,10,15,20-tetrakis(2-N-methylpyridyl)porphyrinatopalladium(II), PdP(2), with B-form DNA duplexes poly(G-C)2, poly(A-T)2, and CT DNA by using combined MCD, CD, and optical data

1998 ◽  
Vol 4 (5) ◽  
pp. 341-352 ◽  
Author(s):  
N. Randy Barnes ◽  
Anton F. Schreiner ◽  
Michael G. Finnegan ◽  
Michael K. Johnson
Keyword(s):  
Optical Data ◽  
Dna Duplexes ◽  
Ct Dna ◽  
Insight Into

SYNTHESIS AND BIOLOGICAL ACTIVITY OF THE NEW PINCER TYPE RUTHENIUM(III) COMPLEX

2021 ◽  
Author(s):  
Ana Rilak Simović ◽  
◽  
Dejan Lazić ◽  
Milica Međedović ◽  
Dušan Ćoćić ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
The Other ◽  
Substitution Reactions ◽  
Biological Targets ◽  
Type Complex ◽  
Calf Thymus ◽  
Vis Spectroscopy ◽  
The Spectator ◽  
Ct Dna ◽  
Insight Into

We synthesized and characterized the ruthenium(III) pincer-type complex [RuCl3(H2Lt-Bu] (H2Lt- Bu = 2,6-bis(5-tert-butyl-1H-pyrazol-3-yl)pyridine, 1) by elemental analysis, IR and UV-Vis spectroscopy, and mass spectrometry (MS) method ESI Q-TOF. For comparison reason, we also studied ruthenium(III) terpyridine complexes of the general formula [Ru(N-N-N)Cl3] where N-N-N = 4′-chloro- terpyridine (Cl-tpy; 2) or 4′-chlorophenyl-terpyridine (Cl-Ph-tpy; 3). Kinetic study of the substitution reactions of 1–3 with biomolecules showed that the rate constants depend on the properties of the spectator ligand and the nature of the entering nucleophile. To gain further insight into the reactivity of ruthenium complexes with potential biological targets, we examined the interactions of 1 – 3 with DNA and HSA. The DNA/HSA binding study showed that in comparison to complex 1 (bis– pyrazolylpyridine), the other two (2 and 3) terpyridine complexes had a slightly better binding affinity to calf thymus DNA (CT DNA), while in the case of human serum albumin (HSA), complex 1 exhibited the most strong quenching ability.

scholarly journals Diurnal regulation of photosynthetic light absorption, electron transport and carbon fixation in two contrasting oceanic environments

2019 ◽  
Vol 16 (7) ◽  
pp. 1381-1399 ◽  
Author(s):  
Nina Schuback ◽  
Philippe D. Tortell
Keyword(s):  
Electron Transport ◽  
Light Absorption ◽  
Carbon Fixation ◽  
Spatial Scales ◽  
Marine Phytoplankton ◽  
Optical Data ◽  
Reaction Centre ◽  
Phytoplankton Productivity ◽  
Ne Pacific ◽  
Insight Into

Abstract. Understanding the dynamics of marine phytoplankton productivity requires mechanistic insight into the non-linear coupling of light absorption, photosynthetic electron transport and carbon fixation in response to environmental variability. In the present study, we examined the variability of phytoplankton light absorption characteristics, light-dependent electron transport and 14C-uptake rates over a 48 h period in the coastal subarctic north-east (NE) Pacific. We observed an intricately coordinated response of the different components of the photosynthetic process to diurnal irradiance cycles, which acted to maximize carbon fixation, while simultaneously preventing damage by excess absorbed light energy. In particular, we found diurnal adjustments in pigment ratios, excitation energy transfer to reaction centre II (RCII), the capacity for non-photochemical quenching (NPQ), and the light efficiency (α) and maximum rates (Pmax) of RCII electron transport (ETRRCII) and 14C uptake. Comparison of these results from coastal waters to previous observations in offshore waters of the subarctic NE Pacific provides insight into the effects of iron limitation on the optimization of photosynthesis. Under iron-limited, low-biomass conditions, there was a significant reduction of iron-rich photosynthetic units per chlorophyll a, which was partly offset by higher light absorption and electron transport per photosystem II (PSII). Iron deficiency limited the capacity of phytoplankton to utilize peak midday irradiance for carbon fixation and caused an upregulation of photoprotective mechanisms, including NPQ, and the decoupling of light absorption, electron transport and carbon fixation. Such decoupling resulted in an increased electron requirement (Φe,C) and decreased quantum efficiency (ΦC) of carbon fixation at the iron-limited station. In both coastal and offshore waters, Φe,C and ΦC correlated strongly to NPQ, albeit with a significantly different slope. We discuss the implications of our results for the interpretation of bio-optical data and the parameterization of numerical productivity models, both of which are vital tools in monitoring marine photosynthesis over large temporal and spatial scales.

Crosslinking of (Cytosine-5)-DNA Methyltransferase SsoII and its Complexes with Specific DNA Duplexes Provides an Insight into Their Structures

2011 ◽  
Vol 30 (7-8) ◽  
pp. 632-650 ◽  
Author(s):  
Alexandra Yurievna Ryazanova ◽  
Ines Winkler ◽  
Peter Friedhoff ◽  
Mikhail Borisovich Viryasov ◽  
Tatiana Semenovna Oretskaya ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Dna Duplexes ◽  
Insight Into

scholarly journals Diurnal regulation of photosynthetic light absorption, electron transport and carbon fixation in two contrasting oceanic environments

2019 ◽  
Author(s):  
Nina Schuback ◽  
Phillipe D. Tortell
Keyword(s):  
Electron Transport ◽  
Light Absorption ◽  
Carbon Fixation ◽  
Spatial Scales ◽  
Marine Phytoplankton ◽  
Optical Data ◽  
Photochemical Quenching ◽  
Phytoplankton Productivity ◽  
Ne Pacific ◽  
Insight Into

Abstract. Understanding the dynamics of marine phytoplankton productivity requires mechanistic insight into the non-linear coupling of light absorption, photosynthetic electron transport and carbon fixation in response to environmental variability. In the present study, we examined the variability of phytoplankton light absorption characteristics, light-dependent electron transport and 14C-uptake rates over a 48 hour period in the coastal Subarctic NE Pacific. We observed an intricately coordinated response of the different components of the photosynthetic process to diurnal irradiance cycles, which acted to maximise carbon fixation while simultaneously preventing damage by excess absorbed light energy. In particular, we found diurnal adjustments in pigment ratios, excitation energy transfer to reaction center II (RCII), the capacity for non-photochemical quenching (NPQ), and the light efficiency (α) and maximum rates (Pmax) of RCII electron transport (ETRRCII) and 14C-uptake. Comparison of these results from coastal waters to previous observations in offshore waters of the Subarctic NE Pacific provided insight into the effects of iron limitation on the optimization of photosynthesis. Under iron-limiting conditions, there was a significant reduction of iron-rich photosynthetic units per chlorophyll a, which was partly offset by higher light absorption and electron transport per photosystem II. Iron deficiency limited the capacity of phytoplankton to utilize peak mid-day irradiance for carbon fixation, and caused an upregulation of photo-protective mechanisms, including NPQ, and the decoupling of light absorption, electron transport and carbon fixation. Such decoupling resulted in an increased electron requirement (Φe,C) and decreased quantum efficiency (ΦC) of carbon fixation at the iron-limited station. In both coastal and off-shore waters, Φe,C and ΦC correlated strongly to NPQ. We discuss the implications of our results for the interpretation of bio-optical data, and the parameterization of numerical productivity models, both of which are vital tools in monitoring marine photosynthesis over large temporal and spatial scales.

scholarly journals Insight into the binding of a non-toxic, self-assembling aromatic tripeptide with ct-DNA: Spectroscopic and viscositic studies

2017 ◽  
Vol 11 ◽  
pp. 112-118 ◽  
Author(s):  
Soumi Biswas ◽  
Satyabrata Samui ◽  
Arpita Chakraborty ◽  
Sagar Biswas ◽  
Debapriya De ◽  
...  
Keyword(s):  
Self Assembling ◽  
Ct Dna ◽  
Insight Into

Calibration problems in hydrogen luminosities

1966 ◽  
Vol 24 ◽  
pp. 322-330
Author(s):  
A. Beer
Keyword(s):  
Galactic Structure ◽  
B Stars ◽  
Insight Into

The investigations which I should like to summarize in this paper concern recent photo-electric luminosity determinations of O and B stars. Their final aim has been the derivation of new stellar distances, and some insight into certain patterns of galactic structure.

Stochasting modeling of planetary ring systems

1984 ◽  
Vol 75 ◽  
pp. 461-469 ◽  
Author(s):  
Robert W. Hart
Keyword(s):  
Maximum Entropy ◽  
Ring System ◽  
The Sun ◽  
Ultimate State ◽  
Interparticle Interactions ◽  
Ring Systems ◽  
First Order ◽  
Planetary Ring ◽  
Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

The spindle stage: A powerful optical tool

1988 ◽  
Vol 46 ◽  
pp. 52-53
Author(s):  
Mickey E. Gunter ◽  
F. Donald Bloss
Keyword(s):  
Significant Error ◽  
Optical Data ◽  
Refractive Indices ◽  
Axis Of Rotation ◽  
Polarizing Microscope ◽  
Microscope Stage

A single, reasonably homogeneous, nonopaque 30-to-300 μm crystal, mounted on a spindle stage and studied by immersion methods under a polarizing microscope, yields optical data frequently sufficient to identify and characterize a substance unequivocally. The data obtainable include (1) the orientation of the crystal's principal vibration axes and (2) its principal refractive indices, to within 0.0002 if desired, for light vibrating along these principal vibration axes. Spindle stages tend to be simple and relatively inexpensive, some costing less than $50. They permit rotation of the crystal about a single axis which is parallel to the microscope stage. This spindle or S-axis is thus perpendicular to the M-axis, namely the microscope stage's axis of rotation.A spindle stage excels when studying anisotropic crystals. It orients uniaxial crystals within minutes and biaxial crystals almost as quickly so that their principal refractive indices - ɛ and ω (uniaxial); α, β and γ (biaxial) - can be determined without significant error from crystal misorientation.

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