Platinum(II) complexes containing hydrazide‐based aminophosphine ligands: Synthesis, molecular structures, computational investigation and evaluation as antitumour agents

2019 ◽  
Vol 33 (6) ◽  
pp. e4873 ◽  
Author(s):  
Khodayar Gholivand ◽  
Yazdan Maghsoud ◽  
Mohammad Kahnouji ◽  
Mahdieh Hosseini ◽  
Mohammad Satari ◽  
...  
Keyword(s):  
Molecular Structures ◽  
Computational Investigation ◽  
Antitumour Agents

Purine complexes of platinum: synthesis, nmr, and crystal and molecular structures of cis-chloro(caffeine)bis(triethylphosphine)platinum(II) fluoroborate and cis-bis(isocaffeine)bis(triethylphosphine)platinum (II) fluoroborate

1983 ◽  
Vol 61 (6) ◽  
pp. 1132-1141 ◽  
Author(s):  
Gordon William Bushnell ◽  
Roderick James Densmore ◽  
Keith Roger Dixon ◽  
Arthur Charles Ralfs
Keyword(s):  
Crystal Structure ◽  
Nmr Spectra ◽  
Molecular Structures ◽  
Platinum Drugs ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Bond Lengths ◽  
Antitumour Agents ◽  
Crystal And Molecular Structures ◽  
Square Planar

Synthesis and 31P nmr spectra of the complex cations, cis-[PtCl(L)(PEt3)2]+, L= theophylline, caffeine, or isocaffeine, and cis[Pt(isocaff)2(PEt3)2]2+ are reported. The crystal structure of cis-[PtCl(caffeine)(PEt3)2][BF4] is determined, space group [Formula: see text], a = 1.1766(6), b = 1.4428(5), c = 0.9002(4) nm, α = 97.28(4)°, β = 97.69(4)°, γ = 100.96(5)°, Dm = 1.649 g cm−1, the bond lengths are Pt—Cl= 233.4(4) pm, Pt—N = 215(1) pm, Pt—P = 225.4(5) pm (mean), and the residual R = 0.071. The crystal structure of cis-[Pt(isocaffeine)2(PEt3)2][BF4]2 is orthorhombic, space group Pbca, a = 2.317(3), b = 1.717(3), c = 2.130(3) nm, Dm = 1.574 g cm−3, with an opposing isocaffeine conformation, bond lengths Pt—N = 211(2) pm, Pt—P = 227.6(9) pm (mean), and R = 0.073. Both crystal structures contain approximately square planar Pt(II) coordination with the purine coordinated via an imidazole nitrogen. The structures are discussed as models for the possible involvement of [Formula: see text] chelation of guanine to platinum when platinum drugs act as antitumour agents, but there is no evidence that isocaffeine acts as an [Formula: see text] chelate.

Electron Microscopy in Molecular Biology

1967 ◽  
Vol 25 ◽  
pp. 2-3
Author(s):  
Cecil E. Hall
Keyword(s):  
Electron Microscopy ◽  
Molecular Biology ◽  
Noise Level ◽  
Molecular Structures ◽  
Material Structure ◽  
The Arts ◽  
Shadow Casting ◽  
Electron Image ◽  
High Degree ◽  
Very High

The visualization of organic macromolecules such as proteins, nucleic acids, viruses and virus components has reached its high degree of effectiveness owing to refinements and reliability of instruments and to the invention of methods for enhancing the structure of these materials within the electron image. The latter techniques have been most important because what can be seen depends upon the molecular and atomic character of the object as modified which is rarely evident in the pristine material. Structure may thus be displayed by the arts of positive and negative staining, shadow casting, replication and other techniques. Enhancement of contrast, which delineates bounds of isolated macromolecules has been effected progressively over the years as illustrated in Figs. 1, 2, 3 and 4 by these methods. We now look to the future wondering what other visions are waiting to be seen. The instrument designers will need to exact from the arts of fabrication the performance that theory has prescribed as well as methods for phase and interference contrast with explorations of the potentialities of very high and very low voltages. Chemistry must play an increasingly important part in future progress by providing specific stain molecules of high visibility, substrates of vanishing “noise” level and means for preservation of molecular structures that usually exist in a solvated condition.

Scanning tunneling microscopy (STM) of DNA and RNA

1989 ◽  
Vol 47 ◽  
pp. 34-35
Author(s):  
Patricia G. Arscott ◽  
Gil Lee ◽  
Victor A. Bloomfield ◽  
D. Fennell Evans
Keyword(s):  
Molecular Structures ◽  
Inorganic Materials ◽  
Resolving Power ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Form And Function ◽  
Dna And Rna ◽  
Calf Thymus ◽  
And Function ◽  
The Relationship

STM is one of the most promising techniques available for visualizing the fine details of biomolecular structure. It has been used to map the surface topography of inorganic materials in atomic dimensions, and thus has the resolving power not only to determine the conformation of small molecules but to distinguish site-specific features within a molecule. That level of detail is of critical importance in understanding the relationship between form and function in biological systems. The size, shape, and accessibility of molecular structures can be determined much more accurately by STM than by electron microscopy since no staining, shadowing or labeling with heavy metals is required, and there is no exposure to damaging radiation by electrons. Crystallography and most other physical techniques do not give information about individual molecules.We have obtained striking images of DNA and RNA, using calf thymus DNA and two synthetic polynucleotides, poly(dG-me5dC)·poly(dG-me5dC) and poly(rA)·poly(rU).

Molecular architecture and functions of the neuronal cytoskeleton

1990 ◽  
Vol 48 (3) ◽  
pp. 2-3
Author(s):  
Nobutaka Hirokawa
Keyword(s):  
Major Elements ◽  
Molecular Structures ◽  
Organelle Transport ◽  
Molecular Architecture ◽  
Neuronal Morphogenesis ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
And Function ◽  
Small Clusters

In this symposium I will present our studies about the molecular architecture and function of the cytomatrix of the nerve cells. The nerve cell is a highly polarized cell composed of highly branched dendrites, cell body, and a single long axon along the direction of the impulse propagation. Each part of the neuron takes characteristic shapes for which the cytoskeleton provides the framework. The neuronal cytoskeletons play important roles on neuronal morphogenesis, organelle transport and the synaptic transmission. In the axon neurofilaments (NF) form dense arrays, while microtubules (MT) are arranged as small clusters among the NFs. On the other hand, MTs are distributed uniformly, whereas NFs tend to run solitarily or form small fascicles in the dendrites Quick freeze deep etch electron microscopy revealed various kinds of strands among MTs, NFs and membranous organelles (MO). These structures form major elements of the cytomatrix in the neuron. To investigate molecular nature and function of these filaments first we studied molecular structures of microtubule associated proteins (MAP1A, MAP1B, MAP2, MAP2C and tau), and microtubules reconstituted from MAPs and tubulin in vitro. These MAPs were all fibrous molecules with different length and formed arm like projections from the microtubule surface.

New designs in cyclophosphazenes as antitumour agents

1980 ◽  
Vol 77 ◽  
pp. 85-89 ◽  
Author(s):  
Jean-François Labarre ◽  
Francois Lahana ◽  
Françoise Sournies ◽  
Suzy Cros ◽  
Georgette François
Keyword(s):  
Antitumour Agents

Toxicity of Heparinoids, with Special Reference to the Precipitation of Fibrinogen

1964 ◽  
Vol 12 (01) ◽  
pp. 232-261 ◽  
Author(s):  
S Sasaki ◽  
T Takemoto ◽  
S Oka
Keyword(s):  
Molecular Weight ◽  
Dextran Sulfate ◽  
Anticoagulant Activity ◽  
Molecular Structures ◽  
Severe Reaction ◽  
Clinical Use ◽  
Molecular Weights ◽  
Close Relationship

SummaryTo demonstrate whether the intravascular precipitation of fibrinogen is responsible for the toxicity of heparinoid, the relation between the toxicity of heparinoid in vivo and the precipitation of fibrinogen in vitro was investigated, using dextran sulfate of various molecular weights and various heparinoids.1. There are close relationships between the molecular weight of dextran sulfate, its toxicity, and the quantity of fibrinogen precipitated.2. The close relationship between the toxicity and the precipitation of fibrinogen found for dextran sulfate holds good for other heparinoids regardless of their molecular structures.3. Histological findings suggest strongly that the pathological changes produced with dextran sulfate are caused primarily by the intravascular precipitates with occlusion of the capillaries.From these facts, it is concluded that the precipitates of fibrinogen with heparinoid may be the cause or at least the major cause of the toxicity of heparinoid.4. The most suitable molecular weight of dextran sulfate for clinical use was found to be 5,300 ~ 6,700, from the maximum value of the product (LD50 · Anticoagulant activity). This product (LD50 · Anticoagulant activity) can be employed generally to assess the comparative merits of various heparinoids.5. Clinical use of the dextran sulfate prepared on this basis gave satisfactory results. No severe reaction was observed. However, two delayed reactions, alopecia and thrombocytopenia, were observed. These two reactions seem to come from the cause other than intravascular precipitation.

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