scholarly journals Interactions of Casein and Polypeptides in Multilayer Films Studied by FTIR and Molecular Dynamics

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 920 ◽  
Author(s):  
Lilianna Szyk-Warszyńska ◽  
Katarzyna Raszka ◽  
Piotr Warszyński
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Grazing Angle ◽  
Multilayer Films ◽  
Attenuated Total Reflection ◽  
Layer By Layer ◽  
Preferential Formation ◽  
Layer Technique ◽  
Dynamics Simulations ◽  
Layer By Layer Technique

Multilayer films containing α- and β-casein and polypeptides, poly-L-lysine (PLL), and poly-L-arginine (PLArg) were formed by the layer-by-layer technique and Fourier Transform InfraRed spectroscopy with Attenuated Total Reflection (FTIR-ATR) and FTIR/Grazing Angle analyzed their infrared spectra. We investigated the changes of conformations of casein and polypeptides in the complexes formed during the build-up of the films. To elucidate the differences in the mechanism of complex formation leading to various growths of (PLL/casein)n and (PLArg/casein)n films, we performed the molecular dynamics simulations of the systems consisting of short PLL and PLArg chains and the representative peptide chains—casein fragments, which consists of several aminoacid sequences. The results of the simulation indicated the preferential formation of hydrogen bonds of poly-L-arginine with phosphoserine and glutamic acid residues of caseins. FTIR spectra confirmed those, which revealed greater conformational changes during the formation of casein complex with poly-L-arginine than with poly-L-lysine resulting from stronger interactions, which was also reflected in the bigger growth of (PLArg/casein)n films with the number of deposited layers.

Structural Inhomogeneity of SrBi2Ta2O9Thin Films Prepared by Layer-by-Layer Technique

2001 ◽  
Vol 688 ◽  
Author(s):  
J. B. Xu ◽  
G. D. Hu ◽  
S. P. Wong
Keyword(s):  
Thin Film ◽  
Profile Analysis ◽  
Grazing Angle ◽  
Grazing Incidence ◽  
Annealing Process ◽  
Layer By Layer ◽  
Depth Profile Analysis ◽  
Structural Orientation ◽  
Layer Technique ◽  
Layer By Layer Technique

AbstractGrazing incidence x-ray diffraction has been employed to perform the depth-profile analysis on SrBi2Ta2O9 (SBT) thin films with different preferential orientations. For the polycrystalline SBT thin film, the change in structural orientation occurs only within the 15-nm-thick top layer, which is associated with the formation of the (200)-predominant SBT thin film prepared by the layer-by-layer annealing process. The inhomogeneity of structural orientation is more significant in the full film thickness for the (200)- predominant SBT thin film. (0010) peak can only be observed for the grazing angle larger than 0.6°. A layer with the highest ratio of I(200)/I(115) is found in the top surface layer (i.e., the latest layer during deposition) of the (200)-predominant SBT thin film.

Fabrication of a-Si:H/nc-Si multilayer films using layer by layer technique and their properties

2002 ◽  
Vol 299-302 ◽  
pp. 1070-1074 ◽  
Author(s):  
V.P Afanasjev ◽  
A.S Gudovskikh ◽  
J.P Kleider ◽  
K.V Koughia ◽  
A.P Sazanov ◽  
...  
Keyword(s):  
Multilayer Films ◽  
Layer By Layer ◽  
Layer Technique ◽  
Layer By Layer Technique

Molecular Basis of Glucose Transport Mechanism in Plants

2019 ◽  
Author(s):  
Balaji Selvam ◽  
Ya-Chi Yu ◽  
Liqing Chen ◽  
Diwakar Shukla
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Molecular Dynamics Simulations ◽  
Conformational Changes ◽  
Transport Mechanism ◽  
Conformational Dynamics ◽  
Site Directed Mutagenesis ◽  
Free Energy Barrier ◽  
Transport Cycle ◽  
Dynamics Simulations

<p>The SWEET family belongs to a class of transporters in plants that undergoes large conformational changes to facilitate transport of sugar molecules across the cell membrane. However, the structures of their functionally relevant conformational states in the transport cycle have not been reported. In this study, we have characterized the conformational dynamics and complete transport cycle of glucose in OsSWEET2b transporter using extensive molecular dynamics simulations. Using Markov state models, we estimated the free energy barrier associated with different states as well as 1 for the glucose the transport mechanism. SWEETs undergoes structural transition to outward-facing (OF), Occluded (OC) and inward-facing (IF) and strongly support alternate access transport mechanism. The glucose diffuses freely from outside to inside the cell without causing major conformational changes which means that the conformations of glucose unbound and bound snapshots are exactly same for OF, OC and IF states. We identified a network of hydrophobic core residues at the center of the transporter that restricts the glucose entry to the cytoplasmic side and act as an intracellular hydrophobic gate. The mechanistic predictions from molecular dynamics simulations are validated using site-directed mutagenesis experiments. Our simulation also revealed hourglass like intermediate states making the pore radius narrower at the center. This work provides new fundamental insights into how substrate-transporter interactions actively change the free energy landscape of the transport cycle to facilitate enhanced transport activity.</p>

scholarly journals Studies of Conformational Changes of Tubulin Induced by Interaction with Kinesin Using Atomistic Molecular Dynamics Simulations

2021 ◽  
Vol 22 (13) ◽  
pp. 6709
Author(s):  
Xiao-Xuan Shi ◽  
Peng-Ye Wang ◽  
Hong Chen ◽  
Ping Xie
Keyword(s):  
Molecular Dynamics ◽  
High Resolution ◽  
Binding Energy ◽  
Molecular Dynamics Simulations ◽  
Conformational Changes ◽  
Weak Interactions ◽  
Molecular Motor ◽  
Structural Data ◽  
Calculated Binding Energy ◽  
Dynamics Simulations

The transition between strong and weak interactions of the kinesin head with the microtubule, which is regulated by the change of the nucleotide state of the head, is indispensable for the processive motion of the kinesin molecular motor on the microtubule. Here, using all-atom molecular dynamics simulations, the interactions between the kinesin head and tubulin are studied on the basis of the available high-resolution structural data. We found that the strong interaction can induce rapid large conformational changes of the tubulin, whereas the weak interaction cannot. Furthermore, we found that the large conformational changes of the tubulin have a significant effect on the interaction of the tubulin with the head in the weak-microtubule-binding ADP state. The calculated binding energy of the ADP-bound head to the tubulin with the large conformational changes is only about half that of the tubulin without the conformational changes.

Pectin-Chitosan Multilayer Coated Microbeads of Diclofenac Sodium Prepared by Layer-by-Layer Technique

2014 ◽  
Vol 1060 ◽  
pp. 45-49
Author(s):  
Kamonrak Cheewatanakornkool ◽  
Pornsak Sriamornsak
Keyword(s):  
Controlled Release ◽  
Drug Release ◽  
Diclofenac Sodium ◽  
Gastric Fluid ◽  
Layer By Layer ◽  
Release Behavior ◽  
Freeze Dried ◽  
Layer Technique ◽  
Calcium Pectinate ◽  
Layer By Layer Technique

The main objective of this study was to fabricate biopolymer-based microbeads, providing enteric properties and controlled release of diclofenac sodium, using layer-by-layer technique. The calcium pectinate microbeads have been designed and coated with chitosan and pectin multilayers. Drug release was performed in simulate gastric fluid (pH 1.2) for 2 hours, followed by pH 6.8 buffer for 8 hours. The effects of chitosan concentration, number of layer and drying technique on drug release were investigated. The results showed that the calcium pectinate microbeads could be simply prepared by ionotropic gelation and then coated with chitosan and pectin solutions using layer-by-layer procedure. The diameter of the microbeads ranged from 800 to 1000 μm for air-dried samples and from 1 to 2 mm for freeze-dried samples. The freeze-dried microbeads had a rough surface and many pores inside, as observed by SEM. The microbeads coated with 4% chitosan/4% pectin revealed a slower drug release than those coated with 1% chitosan/4% pectin and demonstrated a controlled release pattern. Moreover, different drying techniques and numbers of layer also influenced drug release behavior of the prepared microbeads.

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