scholarly journals Effect of Surface Roughness on Aggregation of Polypeptide Chains: A Monte Carlo Study

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 596
Author(s):  
Nguyen Truong Co ◽  
Mai Suan Li

The self-assembly of amyloidogenic peptides and proteins into fibrillar structures has been intensively studied for several decades, because it seems to be associated with a number of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s disease. Therefore, understanding the molecular mechanisms of this phenomenon is important for identifying an effective therapy for the corresponding diseases. Protein aggregation in living organisms very often takes place on surfaces like membranes and the impact of a surface on this process depends not only on the surface chemistry but also on its topology. Our goal was to develop a simple lattice model for studying the role of surface roughness in the aggregation kinetics of polypeptide chains and the morphology of aggregates. We showed that, consistent with the experiment, an increase in roughness slows down the fibril formation, and this process becomes inhibited at a very highly level of roughness. We predicted a subtle catalytic effect that a slightly rough surface promotes the self-assembly of polypeptide chains but does not delay it. This effect occurs when the interaction between the surface and polypeptide chains is moderate and can be explained by taking into account the competition between energy and entropy factors.

2020 ◽  
Vol 27 (9) ◽  
pp. 923-929
Author(s):  
Gaurav Pandey ◽  
Prem Prakash Das ◽  
Vibin Ramakrishnan

Background: RADA-4 (Ac-RADARADARADARADA-NH2) is the most extensively studied and marketed self-assembling peptide, forming hydrogel, used to create defined threedimensional microenvironments for cell culture applications. Objectives: In this work, we use various biophysical techniques to investigate the length dependency of RADA aggregation and assembly. Methods: We synthesized a series of RADA-N peptides, N ranging from 1 to 4, resulting in four peptides having 4, 8, 12, and 16 amino acids in their sequence. Through a combination of various biophysical methods including thioflavin T fluorescence assay, static right angle light scattering assay, Dynamic Light Scattering (DLS), electron microscopy, CD, and IR spectroscopy, we have examined the role of chain-length on the self-assembly of RADA peptide. Results: Our observations show that the aggregation of ionic, charge-complementary RADA motifcontaining peptides is length-dependent, with N less than 3 are not forming spontaneous selfassemblies. Conclusion: The six biophysical experiments discussed in this paper validate the significance of chain-length on the epitaxial growth of RADA peptide self-assembly.


2021 ◽  
Author(s):  
Beatriz Matarranz ◽  
Goutam Ghosh ◽  
Ramesh Kandanelli ◽  
Angel Sampedro ◽  
Kalathil K. Kartha ◽  
...  

We unravel the relationship between conjugation length and self-assembly behaviour of oligophenyleneethynylenes (OPEs).


2007 ◽  
Vol 111 (51) ◽  
pp. 14233-14238 ◽  
Author(s):  
Guillaume Tresset ◽  
Wun Chet Davy Cheong ◽  
Yeng Ming Lam
Keyword(s):  
The Self ◽  

2021 ◽  
Vol 27 ◽  
Author(s):  
Li-Ping Yu ◽  
Ting-Ting Shi ◽  
Yan-Qin Li ◽  
Jian-Kang Mu ◽  
Ya-Qin Yang ◽  
...  

: Mitophagy plays an important role in maintaining mitochondrial quality and cell homeostasis through the degradation of damaged, aged, and dysfunctional mitochondria and misfolded proteins. Many human diseases, particularly neurodegenerative diseases, are related to disorders of mitochondrial phagocytosis. Exploring the regulatory mechanisms of mitophagy is of great significance for revealing the molecular mechanisms underlying the related diseases. Herein, we summarize the major mechanisms of mitophagy, the relationship of mitophagy with human diseases, and the role of traditional Chinese medicine (TCM) in mitophagy. These discussions enhance our knowledge of mitophagy and its potential therapeutic targets using TCM.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fatemeh Narenji Thani ◽  
Ebrahim Mazari ◽  
Somaye Asadi ◽  
Maryam Mashayekhikhi

PurposeConsidering innovation and its improvement as an essential strategy to enable organizations to continue their lives in the new competitive environment leads to a focus on employees' self-development as a factor that affects human resource agility (HRA) and the tendency toward organizational innovation. Consequently, the purpose of the study was to explain the impact of self-development on the tendency toward organizational innovation with the role of the mediator, HRA in higher education institutions as one of the most important and vital organizations in any society.Design/methodology/approachThe study was an applicable one with the quantitative approach using the descriptive–correlative method. The population consisted of 477 nonacademic employees of Kharazmi University among whom 214 ones were selected as the sample group, using a simple random sampling technique. Data were collected through the self-development, HRA and the tendency toward organizational innovation questionnaires and then analyzed using the structural equation modeling approach.FindingsThe study findings revealed a positive impact of self-development on the HRA (γ = 0/79) and HRA on the tendency toward organizational innovation (β = 0/6). Also, self-development with mediating HRA impacts the tendency toward organizational innovation (β = 0/58). Finally, self-development had no direct impact on the tendency toward organizational innovation.Research limitations/implicationsTaking the circumstances of doing this research into consideration, if there were the opportunity to do the research on the staffs of more than one university simultaneously and categorize the university staff into executives, managers and experts, more favorable results could be achieved. Also, considering group and organizational factors with the attention to the self-development approach and its factors would provide more awareness-training information on the higher education system in Iran. For future researches, both the individual and group factors are suggested to be surveyed and compared, to assess the weight and impact of these factors all together and to provide an adequate clarification of the role of the group and the organization. Finally, in future studies, it is also recommended that a qualitative approach be used to reach deeper clarifications on the aspects of these variables in the context of higher education.Practical implicationsThese findings have major practical implications concerning the higher educational settings. The findings of this study must give significant and practical insights for policymakers of universities and other higher education stakeholders, as well as recommendations to the academic community for further research in this area. First, they should recognize that nonacademic staff members are professional employees who contribute to improving organizational innovation. Higher education must focus on designing and implementing successful mechanisms and a well-planned self-development program that can help and promote the self-development approach among all staff. If the above-mentioned programs are designed based on the employees' needs analysis, they will get trained in a way to enhance mental and behavioral flexibility. The programs with such an approach can result in the proactive, adaptive, resilient behavior and agility of HR.Originality/valueThe model for this study has integrated and prioritized the key innovation drivers that would help universities design, adopt and implement policies and practices that facilitate and encourage improvements and adaptation to a fast-paced environment. Furthermore, the convincing reason for the significance of the current research is that although several types of research have been carried out on each of these three variables in different contexts separately, very few studies, like this, have directly examined the correlation between these three variables among the non-academic staff in higher education institutes. So, given the importance of the issue and rare availability of evidence in this regard, the authors were intrigued to discover whether the self-development through the mediation of HRA could reinforce and strengthen the tendency toward organizational innovation and whether HRA could be an appropriate mediator of the relationship between self-development and the tendency toward organizational innovation among the nonacademic staff of Kharazmi University as one of the most prestigious and celebrated universities in Iran.


Author(s):  
Robert K. Logan

In this presentation we will study propagating organization. We begin by examining the evolution and origin of language by briefly reviewing the impact of the phonetic alphabet (Logan 2004a), the evolution of notated language (Logan 2004b), the origin of language and culture (Logan 2006, 2007), the role of collaboration in knowledge management (Logan and Stokes 2004), the impact of “new media” (Logan in preparation). We will then connect this work to the propagating organization of all living organisms (Kauffman et al. in press) where we will show that information in biotic systems are the constraints that instruct living organisms how to operate. We will demonstrate that instructional or biotic information is quite different than the classical notion of information Shannon developed for addressing engineering problems in telecommunications. We also will show that biosemiosis is in some sense equivalent to propagating organization (Kauffman et al. in press). We then conclude our presentation with the speculation that there exist at least seven levels of biosemiosis.


2012 ◽  
Vol 550-553 ◽  
pp. 57-61
Author(s):  
Hao Li ◽  
Yong Hong Deng ◽  
Kai Huang

Alkali lignin (AL) was used as a polyanion to form layer-by-layer self-assembled film with PDAC as a polycation. The effects of temperature and concentration on the adsorption characteristics of AL were investigated. Iodine was added into AL solutions to study the role of π-π interaction in self-assembly of AL and PDAC. Results show that the self-assembly of AL/PDAC is mainly driven by π-π interaction and electrostatic interaction. A higher temperature or a larger concentration can enhance the aggregation of lignin. I2 can form lignin–iodine charge–transfer complexes with AL to reduce the degree of aggregation of AL, so the adsorbed amount of AL decreases significantly with increasing iodine contents.


2017 ◽  
Vol 129 (43) ◽  
pp. 13473-13477 ◽  
Author(s):  
Shibaji Basak ◽  
Ishwar Singh ◽  
Annaleizle Ferranco ◽  
Jebreil Syed ◽  
Heinz-Bernhard Kraatz
Keyword(s):  

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