scholarly journals On the question of two-step nucleation in protein crystallization

2015 ◽  
Vol 179 ◽  
pp. 41-58 ◽  
Author(s):  
Andrea Sauter ◽  
Felix Roosen-Runge ◽  
Fajun Zhang ◽  
Gudrun Lotze ◽  
Artem Feoktystov ◽  
...  
Keyword(s):  
Real Time ◽  
Intermediate Phase ◽  
Early Stage ◽  
Protein Crystallization ◽  
Structural Evolution ◽  
Equation Model ◽  
Nucleation Mechanism ◽  
Crystal Nucleation ◽  
Time Study ◽  
Nucleation Kinetics

We report a real-time study on protein crystallization in the presence of multivalent salts using small angle X-ray scattering (SAXS) and optical microscopy, focusing particularly on the nucleation mechanism as well as on the role of the metastable intermediate phase (MIP). Using bovine beta-lactoglobulin as a model system in the presence of the divalent salt CdCl2, we have monitored the early stage of crystallization kinetics which demonstrates a two-step nucleation mechanism: protein aggregates form a MIP, which is followed by the nucleation of crystals within the MIP. Here we focus on characterizing and tuning the structure of the MIP using salt and the related effects on the two-step nucleation kinetics. The results suggest that increasing the salt concentration near the transition zonepseudo-c** enhances the energy barrier for both MIPs and crystal nucleation, leading to slow growth. The structural evolution of the MIP and its effect on subsequent nucleation is discussed based on the growth kinetics. The observed kinetics can be well described, using a rate-equation model based on a clear physical two-step picture. This real-time study not only provides evidence for a two-step nucleation process for protein crystallization, but also elucidates the role and the structural signature of the MIPs in the nonclassical process of protein crystallization.

Study of the early Stage of Deposition Process for Electrodeposited Ni100-XFeX Thin Films

2011 ◽  
Vol 495 ◽  
pp. 1-4 ◽  
Author(s):  
Saci Messaadi ◽  
Mosbah Daamouche ◽  
Abderrahim Guittoum ◽  
Hadria Medouer ◽  
Noureddine Fenineche ◽  
...  
Keyword(s):  
Experimental Data ◽  
Electrochemical Method ◽  
Early Stage ◽  
Structural Evolution ◽  
Deposition Process ◽  
Optimal Conditions ◽  
X Ray Diffraction ◽  
Nucleation Kinetics ◽  
Theoretical Methods ◽  
X Ray

The aim of this work is to understand the early stages in the growth mechanism of invar (Fe64Ni34) alloys and also to study the influence of potential on the evolution of their crystalline structures. Fe64Ni34 layers were deposited onto copper substrates under optimal conditions using the electrochemical method of cyclic voltammetry (CV) and chronoamperometry (CA). The influence of the potential is examined and the nucleation kinetics is discussed. In this purpose, the obtained experimental data was interpreted by applying useful theoretical methods developed by Scharifker and Hills. X-ray diffraction experiments were performed on all samples in order to follow the structural evolution of Fe64Ni34 layers as a function of the potential.

scholarly journals Nonclassical Nucleation—Role of Metastable Intermediate Phase in Crystal Nucleation: An Editorial Prefix

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 174
Author(s):  
Fajun Zhang ◽  
José A. Gavira ◽  
Geun Woo Lee ◽  
Dirk Zahn
Keyword(s):  
Intermediate Phase ◽  
Solid Phase ◽  
Early Stage ◽  
Order Parameters ◽  
Nucleation Theory ◽  
Crystal Nucleation ◽  
Classical Nucleation Theory ◽  
Supersaturated Solution ◽  
Liquid Phases

Classical nucleation theory (CNT), which was established about 90 years ago, represents the most commonly used theory in describing nucleation processes. For a fluid-to-solid phase transition, CNT states that the solutes in a supersaturated solution reversibly form small clusters. Once a cluster reaches its critical size, it becomes thermodynamically stable and is favored for further growth. One of the most important assumptions of CNT is that the nucleation process is described by one reaction coordinate and all order parameters proceed simultaneously. Recent studies in experiments, computer simulations, and theory have revealed nonclassical features in the early stage of nucleation. In particular, the decoupling of order parameters involved during a fluid-to-solid transition leads to the so-called two-step nucleation mechanism, in which a metastable intermediate phase (MIP) exists in parallel to the initial supersaturated solution and the final crystals. These MIPs can be high-density liquid phases, mesoscopic clusters, or preordered states. In this Special Issue, we focus on the role of the various MIPs in the early stage of crystal nucleation of organic materials, metals and alloys, aqueous solutions, minerals, colloids, and proteins, and thus on various scenarios of nonclassical pathways of crystallization.

Kinetics of Ni-Nano Cr2O3 Composite Coating during Early Electro-Crystallization Processes

2013 ◽  
Vol 785-786 ◽  
pp. 938-943 ◽  
Author(s):  
Li Bin Yu ◽  
Qi Jun Zhong ◽  
Yi Xiao ◽  
Jian Feng Gu ◽  
Qing Dong Zhong
Keyword(s):  
Composite Coating ◽  
Composite System ◽  
Nucleation Mechanism ◽  
Crystal Nucleation ◽  
Nucleation Process ◽  
Nucleation Kinetics ◽  
Instantaneous Nucleation ◽  
Nucleation Model ◽  
Progressive Nucleation ◽  
Kinetics Of

Nucleation kinetics of Ni-nanoCr2O3composite coating during early electro-crystallization was investigated. The results showed that, the early electro-crystallization processes of Ni-nanoCr2O3composite coating and pure Ni coating followed a Scharifker-Hill nucleation/growth mechanism. At the low potential, the nucleation process of pure Ni and Ni-Cr2O3composite system may approach to the progressive nucleation model; With the overpotential increasing, the nucleation model of Pure Ni and Ni-Cr2O3composite system converts into the instantaneous nucleation mechanism controlled; at the same overpotential, Cr2O3powder promotes the electro-crystallization nucleation of Ni. But at high negative potential, Cr2O3powder in composite system promotes the electro-crystal nucleation of Ni weakly; the nanoCr2O3powder added reduces the current efficiency in the nucleation process of Ni.

Early stages of protein crystallization as revealed by emerging optical waveguide technology

2008 ◽  
Vol 41 (3) ◽  
pp. 523-530 ◽  
Author(s):  
Attia Boudjemline ◽  
David T. Clarke ◽  
Neville J. Freeman ◽  
James M. Nicholson ◽  
Gareth R. Jones
Keyword(s):  
Real Time ◽  
Optical Waveguide ◽  
Early Stage ◽  
Protein Crystallization ◽  
Protein Aggregates ◽  
Crystal Formation ◽  
Polarization Interferometry ◽  
Dual Polarization Interferometry ◽  
Salt Crystals ◽  
High Supersaturation

A highly sensitive method for studying the onset of protein crystallization in real time using an optical-waveguide-based technique is reported. Dual polarization interferometry uses light from sensing and reference waveguides to produce an interference pattern, which when the sensing waveguide is immersed in a protein solution supplies information on the thickness and density of any protein adlayer on the sensing waveguide's surface. This technique provides evidence that crystallization proceedsvialarge protein aggregates but, more strikingly, shows dramatic light loss from the sensing waveguide at a very early stage during crystallization. The technique proves relatively insensitive to the crystallization of small molecules or poorly formed protein crystals and affords a method of distinguishing crystal formation from the formation of other protein aggregates or salt crystals. The experimental setup currently necessitates crystallization using the batch method, and precipitant mixing at high supersaturation is known to introduce a greater variability compared with methods such as vapour diffusion or dialysis, but first results promise to bridge the paucity of real-time methods available to distinguish the onset of protein crystallization from other forms of aggregation.

Examining Protein Crystallization Using Scanning Electron Microscopy

2012 ◽  
Vol 19 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Kathryn Gomery ◽  
Elaine C. Humphrey ◽  
Rodney Herring
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Crystal Growth ◽  
Early Stage ◽  
Protein Crystallization ◽  
Crystal Nucleation ◽  
Protein Crystal ◽  
Microscopy Imaging ◽  
Protein Crystal Growth ◽  
Scanning Electron

AbstractElucidation of protein structure using X-ray crystallography relies on the quality of the crystal. Crystals suffer from many different types of disorder, some of which occur during crystal nucleation and early crystal growth. To date, there are few studies surrounding the quality and nucleation of protein crystals partly due to difficulties surrounding viewing biological samples at high resolution. Recent research has led our current understanding of nucleation to be a two-step mechanism involving the formation of nuclei from dense liquid clusters; it is still unclear whether nuclei first start as amorphous aggregate or as crystalline lattices. Our research examines this mechanism through the use of electron microscopy. Using scanning electron microscopy imaging of the protein crystal growth process, a stacking, spiraling manner of growth is observed. The tops of the pyramid-like tetragonal protein crystal structures measure ~0.2 μm across and contain ~125,000 lysozyme units. This noncrystalline area experiences strain due to growth of the protein crystal. Our work shows that it is possible to view detailed early stage protein crystal growth using a wet scanning electron microscopy technique, thereby overcoming the problem of viewing liquids in a vacuum.

scholarly journals An in-situ real time study of the perovskite film micro-structural evolution in a humid environment by using synchrotron based characterization technique

2017 ◽  
Vol 66 (1) ◽  
pp. 018401
Author(s):  
Yang Ying-Guo ◽  
Yin Guang-Zhi ◽  
Feng Shang-Lei ◽  
Li Meng ◽  
Ji Geng-Wu ◽  
...  
Keyword(s):  
Real Time ◽  
Structural Evolution ◽  
Time Study ◽  
Humid Environment ◽  
Characterization Technique

Long n-Alkane Adlayers as Templates for Tailoring Supramolecular Self-Assemblies on Surfaces

2006 ◽  
Vol 937 ◽  
Author(s):  
Luc Piot ◽  
Alexandr Marchenko ◽  
Jishan Wu ◽  
Klaus Müllen ◽  
Denis Fichou
Keyword(s):  
Phase Transitions ◽  
Real Time ◽  
Direct Evidence ◽  
Early Stage ◽  
Structural Evolution ◽  
Heteroepitaxial Growth ◽  
Solid Interface ◽  
Successive Phase

ABSTRACTIn this paper we report the heteroepitaxial growth and the structural evolution of hexakis-dodecyl-peri-hexabenzocoronene (HBC-C12) adsorbed on a template monolayer (n-C50H102). STM measurements at the liquid/solid interface made it possible to follow in real time the early stage of deposition of the HBC-C12 molecules. Additionally, molecule manipulations were realized using the tip of the STM. Our measurements give direct evidence of two successive phase transitions occurring in the upper HBC monolayer weakly bonded to the underlying template layer.

Pattern Formation in Thin Polymer Films: A New Morphology

2000 ◽  
Vol 629 ◽  
Author(s):  
Jean-Loup Masson ◽  
Peter F. Green
Keyword(s):  
Growth Rate ◽  
Pattern Formation ◽  
Early Stage ◽  
Structural Evolution ◽  
Distinct Form ◽  
Thin Polymer Films ◽  
Intermediate Morphology ◽  
Thin Polymer ◽  
Nonwetting Liquid ◽  
Cylindrical Holes

ABSTRACTResearchers have shown that thin, nonwetting, liquid homopolymer films dewet substrates, forming patterns that reflect fluctuations in the local film thickness. These patterns have been shown to be either discrete cylindrical holes or bicontinuous “spinodal-like” patterns. In this paper we show the existence of a new morphology. During the early stage of dewetting, discrete highly asymmetric holes appear spontaneously throughout the film. The nucleation rate of these holes is faster than their growth rate. The morphology of the late stage of evolution, after 18 days, is characterized by a bicontinuous pattern, distinct form conventional spinodal dewetting patterns. This morphology has been observed for a range of film thicknesses between 7.5 and 21nm. The structural evolution of this intermediate morphology is discussed.

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