Effective masses and surface-corrugation energies of bound-state levels in atom-surface scattering

1986 ◽  
Vol 33 (8) ◽  
pp. 5652-5656 ◽  
Author(s):  
Nicolas Garcia ◽  
Frank O. Goodman
Keyword(s):  
Bound State ◽  
Surface Scattering ◽  
Surface Corrugation ◽  
Effective Masses

BENCHMARKING PATTERSON ANALYSIS IN HELIUM ATOM SCATTERING

2007 ◽  
Vol 14 (01) ◽  
pp. 1-4 ◽  
Author(s):  
IG. SHUTTLEWORTH
Keyword(s):  
Fourier Series ◽  
Helium Atom ◽  
Surface Scattering ◽  
Standard Formulation ◽  
Momentum Exchange ◽  
Helium Atom Scattering ◽  
Surface Corrugation ◽  
Patterson Function ◽  
Atom Scattering

The technique of Patterson analysis has proven to be a powerful tool in the deduction of structures, both in 2- and 3-D. Using the standard formulation of the Patterson function, the process has been benchmarked for the Helium Atom Scattering (HAS) experiment. Analytically expanding the Patterson function reveals a straightforward Fourier series, whose coefficients are explicit functions of the surface corrugation and the momentum exchange during scattering. Examples based on this formulation reveal that in surface scattering experiments, the Patterson formulation may not be directly interpreted as a map of the inter-nuclear distances, but as a function of surface corrugation and perpendicular momentum exchange.

Image States: Binding Energies, Effective Masses, and Surface Corrugation

1985 ◽  
Vol 54 (6) ◽  
pp. 591-594 ◽  
Author(s):  
N. Garcia ◽  
B. Reihl ◽  
K. H. Frank ◽  
A. R. Williams
Keyword(s):  
Binding Energies ◽  
Surface Corrugation ◽  
Effective Masses ◽  
Image States

CRYO-Electron Microscopy of the Acto-Myosin-ATP Complex

1990 ◽  
Vol 48 (1) ◽  
pp. 248-249
Author(s):  
John Trinickt ◽  
Howard White
Keyword(s):  
Electron Microscopy ◽  
Atp Hydrolysis ◽  
Myosin Head ◽  
Bound State ◽  
Cross Linking ◽  
Weakly Bound ◽  
Cryo Electron Microscopy ◽  
Myosin Subfragment 1 ◽  
Attached State ◽  
High Fraction

The primary force of muscle contraction is thought to involve a change in the myosin head whilst attached to actin, the energy coming from ATP hydrolysis. This change in attached state could either be a conformational change in the head or an alteration in the binding angle made with actin. A considerable amount is known about one bound state, the so-called strongly attached state, which occurs in the presence of ADP or in the absence of nucleotide. In this state, which probably corresponds to the last attached state of the force-producing cycle, the angle between the long axis myosin head and the actin filament is roughly 45°. Details of other attached states before and during power production have been difficult to obtain because, even at very high protein concentration, the complex is almost completely dissociated by ATP. Electron micrographs of the complex in the presence of ATP have therefore been obtained only after chemically cross-linking myosin subfragment-1 (S1) to actin filaments to prevent dissociation. But it is unclear then whether the variability in attachment angle observed is due merely to the cross-link acting as a hinge.We have recently found low ionic-strength conditions under which, without resorting to cross-linking, a high fraction of S1 is bound to actin during steady state ATP hydrolysis. The structure of this complex is being studied by cryo-electron microscopy of hydrated specimens. Most advantages of frozen specimens over ambient temperature methods such as negative staining have already been documented. These include improved preservation and fixation rates and the ability to observe protein directly rather than a surrounding stain envelope. In the present experiments, hydrated specimens have the additional benefit that it is feasible to use protein concentrations roughly two orders of magnitude higher than in conventional specimens, thereby reducing dissociation of weakly bound complexes.

A Two-scale Model for Composite Rough Surface Scattering

PIERS Online ◽  
2007 ◽  
Vol 3 (5) ◽  
pp. 718-722 ◽  
Author(s):  
Wenzhe Yan ◽  
L. X. Xu ◽  
Yang Du ◽  
F. Sheng ◽  
Z. N. Li ◽  
...  
Keyword(s):  
Rough Surface ◽  
Surface Scattering ◽  
Scale Model ◽  
Rough Surface Scattering

Binding Mechanism and Structural Insights into the Identified Protein Target of Covid-19 with In-Vitro Effective Drug Ivermectin

2020 ◽  
Author(s):  
Parth Sarthi Sen Gupta ◽  
Satyaranjan Biswal ◽  
Saroj Kumar Panda ◽  
Abhik Kumar Ray ◽  
Malay Kumar Rana
Keyword(s):  
Ternary Complex ◽  
Bound State ◽  
Molecular Target ◽  
Cooperative Interaction ◽  
Effective Drug ◽  
Rna Dependent Rna Polymerase ◽  
Protein Target ◽  
Ternary Complex Formation ◽  
Structural Insights

<p>While an FDA approved drug Ivermectin was reported to dramatically reduce the cell line of SARS-CoV-2 by ~5000 folds within 48 hours, the precise mechanism of action and the COVID-19 molecular target involved in interaction with this in-vitro effective drug are unknown yet. Among 12 different COVID-19 targets studied here, the RNA dependent RNA polymerase (RdRp) with RNA and Helicase NCB site show the strongest affinity to Ivermectin amounting -10.4 kcal/mol and -9.6 kcal/mol, respectively. Molecular dynamics of corresponding protein-drug complexes reveals that the drug bound state of RdRp with RNA has better structural stability than the Helicase NCB site, with MM/PBSA free energy of -135.2 kJ/mol, almost twice that of Helicase (-76.6 kJ/mol). The selectivity of Ivermectin to RdRp is triggered by a cooperative interaction of RNA-RdRp by ternary complex formation. Identification of the target and its interaction profile with Ivermectin can lead to more powerful drug designs for COVID-19 and experimental exploration. </p>

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