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Protein aggregation

Ipsita Roy, Joyeeta Mukherjee, Munishwar N Gupta
Extensive cross-linking of a precipitate of a protein by a cross-linking reagent (glutaraldehyde has been most commonly used) creates an insoluble enzyme preparation called cross-linked enzyme aggregates (CLEAs). CLEAs show high stability and performance in conventional aqueous as well as nonaqueous media. These are also stable at fairly high temperatures. CLEAs with more than one kind of enzyme activity can be prepared, and such CLEAs are called combi-CLEAs or multipurpose CLEAs. Extent of cross-linking often influences their morphology, stability, activity, and enantioselectivity...
2017: Methods in Molecular Biology
David J Koss, Glynn Jones, Anna Cranston, Heidi Gardner, Nicholas M Kanaan, Bettina Platt
Post-mortem investigations of human Alzheimer's disease (AD) have largely failed to provide unequivocal evidence in support of the original amyloid cascade hypothesis, which postulated deposition of β-amyloid (Aβ) aggregates to be the cause of a demented state as well as inductive to tau neurofibrillary tangles (NFTs). Conflicting evidence suggests, however, that Aβ plaques and NFTs, albeit to a lesser extent, are present in a substantial subset of non-demented individuals. Hence, a range of soluble tau and Aβ species has more recently been implicated as the disease-relevant toxic entities...
October 21, 2016: Acta Neuropathologica
Shu-Yu Wu, Ping Zou, Alexandra W Fuller, Sanjay Mishra, Zhen Wang, Kevin L Schey, Hassane S Mchaourab
The refractivity and transparency of the ocular lens is dependent on the stability and solubility of the crystallins in the fiber cells. A number of mutations of lens crystallins have been associated with dominant cataracts in humans and mice. Of particular interest were γB- and γD-crystallin mutants linked to dominant cataracts in mouse models. While thermodynamically destabilized and aggregation-prone, these mutants were found to have weak affinity to the resident chaperone α-crystallin in vitro To better understand the mechanism of the cataract phenotype, we transgenically expressed different γD-crystallin mutants in the zebrafish lens, and observed a range of lens defects that arise primarily from the aggregation of the mutant proteins...
October 21, 2016: Journal of Biological Chemistry
A Reum Kim, Ki Bum Ahn, Hyun Young Kim, Ho Seong Seo, Cheol-Heui Yun, Seung Hyun Han
INTRODUCTION: Streptococcus gordonii is a predominant member of the oral microflora and has been isolated from root canals of teeth with refractory apical periodontitis. Biofilm formation is important for various dental diseases, and S. gordonii is involved in dental biofilm formation as an early colonizer. Although serine-rich repeat (SRR) adhesins of S. gordonii such as gordonii surface protein B (GspB) are associated with bacterial colonization, the role of GspB in biofilm formation is not clearly understood...
October 18, 2016: Journal of Endodontics
Carsten Deppermann, Paul Kubes
The primary function of platelets is to patrol the vasculature and seal vessel breaches to limit blood loss. However, it is becoming increasingly clear that they also contribute to pathophysiological conditions like thrombosis, atherosclerosis, stroke and infection. Severe sepsis is a devastating disease that claims hundreds of thousands of lives every year in North America and is a major burden to the public health system. Platelet surface receptors like GPIb, αIIbβ3, TLR2 and TLR4 are involved in direct platelet-bacteria interactions...
October 18, 2016: Seminars in Immunology
Paul A Gurbel, Kevin P Bliden, Rahul Chaudhary, Jeff Patrick, Fang Liu, Gailing Chen, Christopher McLeod, Udaya S Tantry
High platelet reactivity and high platelet turnover have been implicated in incomplete platelet inhibition during immediate-release acetylsalicylic acid therapy in patients with type 2 diabetes mellitus (DM). An extended-release acetylsalicylic acid (ER-ASA; Durlaza) formulation was developed to provide 24-hour antithrombotic effects with once-daily dosing. The objective of the study was to evaluate the antiplatelet effects of ER-ASA in patients with DM. In this open-label, single-center study, patients with DM (n = 40) and multiple cardiovascular risk factors received ER-ASA 162...
September 20, 2016: American Journal of Cardiology
Ahmed I Nossier, Ola S Mohammed, Rasha R Fakhr El-Deen, Ashraf S Zaghloul, Sanaa Eissa
Matrix metalloproteinases (MMPs), in particularly gelatinases (MMP-2 and MMP-9) were reported as urinary markers of bladder cancer. In this work, we developed a simple colorimetric gold nanoparticle (AuNP) assay for rapid and sensitive detection of urinary total gelatinase activity based on the surface plasmon resonance (SPR) property of AuNPs. Gelatin-modified AuNPs were stably suspended in solution even upon addition of an aggregation inducer as 6-mercaptohexan-1-ol (6-MCH). Gelatinases digest gelatin capping...
December 1, 2016: Talanta
A D Surowka, M Töpperwien, M Bernhardt, J D Nicolas, M Osterhoff, T Salditt, D Adamek, M Szczerbowska-Boruchowska
Human dopaminergic system in general, and substantia nigra (SN) neurons, in particular, are implicated in the pathologies underlying the human brain aging. The interplay between aberrations in the structural organization and elemental composition of SN neuron bodies has recently gained in importance as selected metals: Fe, Cu, Zn, Ca were found to trigger oxidative-stress-mediated aberration in their molecular assembly due to concomitant protein (alpha-synuclein, tau-protein) aggregation, gliosis and finally oxidative stress...
December 1, 2016: Talanta
Isabel P G Fernandes, Ana Maria Oliveira-Brett
Calmodulin (CaM) is an essential protein present in all eukaryote cells, ranging from vertebrates to unicellular organisms. CaM is the most important Ca(2+) signalling protein, composed of two domains, N- and C-terminal domains, linked by a flexible central α-helix, and is responsible for the regulation of numerous calcium-mediated signalling pathways. Four calcium ions bind to CaM, changing its conformation and determining how it recognizes and regulates its cellular targets. The oxidation mechanism of native and denatured CaM, at a glassy carbon electrode, was investigated using differential pulse voltammetry and electrochemical impedance spectroscopy...
October 7, 2016: Bioelectrochemistry
Katharina Grundler, Raffaela Rotter, Sloane Tilley, Joachim Pircher, Thomas Czermak, Mustaf Yakac, Erik Gaitzsch, Steffen Massberg, Florian Krötz, Hae-Young Sohn, Ulrich Pohl, Hanna Mannell, Bjoern F Kraemer
INTRODUCTION: Platelets possess critical hemostatic functions in the system of thrombosis and hemostasis, which can be affected by a multitude of external factors. Previous research has shown that platelets have the capacity to synthesize proteins de novo and more recently a multicatalytic protein complex, the proteasome, has been discovered in platelets. Due to its vital function for cellular integrity, the proteasome has become a therapeutic target for anti-proliferative drug therapies in cancer...
October 13, 2016: Thrombosis Research
Kirilka Mladenova, Svetla D Petrova, Tonya D Andreeva, Veselina Moskova-Doumanova, Tanya Topouzova-Hristova, Yuri Kalvachev, Konstantin Balashev, Shomi S Bhattacharya, Christina Chakarova, Zdravko Lalchev, Jordan A Doumanov
Human bestrophin-1 (hBest1) is a transmembrane calcium-activated chloride channel protein - member of the bestrophin family of anion channels, predominantly expressed in the membrane of retinal pigment epithelium (RPE) cells. Mutations in the protein cause ocular diseases, named Bestrophinopathies. Here, we present the first Fourier transform infrared (FTIR) study of the secondary structure elements of hBest1, π/A isotherms and hysteresis, Brewster angle microscopy (BAM) and atomic force microscopy (AFM) visualization of the aggregation state of protein molecules dispersed as Langmuir and Langmuir-Blodgett films...
October 13, 2016: Colloids and Surfaces. B, Biointerfaces
Shobini Jayaraman, Jose Luis Sánchez-Quesada, Olga Gursky
Lipids in the body are transported via lipoproteins that are nanoparticles comprised of lipids and amphipathic proteins termed apolipoproteins. This family of lipid surface-binding proteins is over-represented in human amyloid diseases. In particular, all major proteins of high-density lipoproteins (HDL), including apoA-I, apoA-II and serum amyloid A, can cause systemic amyloidoses in humans upon protein mutations, post-translational modifications or overproduction. Here, we begin to explore how the HDL lipid composition influences amyloid deposition by apoA-I and related proteins...
October 18, 2016: Biochimica et Biophysica Acta
Majid Jafari, Faramarz Mehrnejad
Changes in the tertiary structure of proteins and the resultant fibrillary aggregation could result in fatal heredity diseases, such as lysozyme systemic amyloidosis. Human lysozyme is a globular protein with antimicrobial properties with tendencies to fibrillate and hence is known as a fibril-forming protein. Therefore, its behavior under different ambient conditions is of great importance. In this study, we conducted two 500000 ps molecular dynamics (MD) simulations of human lysozyme in sodium dodecyl sulfate (SDS) at two ambient temperatures...
2016: PloS One
Oznur Bayraktar, Ozlem Oral, Nur Mehpare Kocaturk, Yunus Akkoc, Karin Eberhart, Ali Kosar, Devrim Gozuacik
The ubiquitin-proteasome system (UPS) degrades soluble proteins and small aggregates, whereas macroautophagy (autophagy herein) eliminates larger protein aggregates, tangles and even whole organelles in a lysosome-dependent manner. VCP/p97 was implicated in both pathways. VCP/p97 mutations cause a rare multisystem disease called IBMPFD (Inclusion Body Myopathy with Paget's Disease and Frontotemporal Dementia). Here, we studied the role IBMPFD-related mutants of VCP/p97 in autophagy. In contrast with the wild-type VCP/p97 protein or R155C or R191Q mutants, the P137L mutant was aggregate-prone...
2016: PloS One
Marion T Turnbull, Elizabeth J Coulson
Alzheimer's disease (AD) is a progressive, irreversible neurodegenerative disease that destroys memory and cognitive function. Aggregates of hyperphosphorylated tau protein are a prominent feature in the brain of patients with AD, and are a major contributor to neuronal toxicity and disease progression. However, the factors that initiate the toxic cascade that results in tau hyperphosphorylation in sporadic AD are unknown. Here we investigated whether degeneration of basal forebrain cholinergic neurons (BFCNs) and/or a resultant decrease in neurotrophin signaling cause aberrant tau hyperphosphorylation...
October 20, 2016: Journal of Alzheimer's Disease: JAD
Nathan A Bernhardt, Wenhui Xi, Wei Wang, Ulrich H E Hansmann
Recent experiments suggest that an amino acid sequence encodes not only the native fold of a protein but also other forms essential for its function, or important during folding or association. These various forms populate a multi-funnel folding and association landscape where mutations, changes in environment or interaction with other molecules switch between the encoded folds. We introduce replica-exchange-with- tunneling as a way to simulate efficiently switching between distinct folds of proteins and protein aggregates...
October 21, 2016: Journal of Chemical Theory and Computation
Yun-Wen Yang, Chun-Mei Zhang, Xian-Jie Huang, Xiao-Xin Zhang, Lin-Kai Zhang, Jia-Huang Li, Zi-Chun Hua
Fas-associated protein with death domain (FADD), a pivotal adaptor protein transmitting apoptotic signals, is indispensable for the induction of extrinsic apoptosis. However, overexpression of FADD can form large, filamentous aggregates, termed death effector filaments (DEFs) by self-association and initiate apoptosis independent of receptor cross-linking. A mutant of FADD, which is truncated of the C-terminal tail (m-FADD, 182-205 aa) named N-FADD (m-FADD, 1-181 aa), can dramatically up-regulate the strength of FADD self-association and increase apoptosis...
October 21, 2016: Scientific Reports
Joan Yw Liu, Cheryl Reeves, Beate Diehl, Antonietta Coppola, Aliya Al-Hajri, Chandrashekar Hoskote, Salim Al Mughairy, Mohamed Tachrount, Michael Groves, Zuzanna Michalak, Kevin Mills, Andrew W McEvoy, Anna Miserocchi, Sanjay M Sisodiya, Maria Thom
OBJECTIVE: This study reports on a novel brain pathology in young patients with Frontal Lobe Epilepsy that is distinct from Focal Cortical Dysplasia. METHODS: Surgical specimens from twenty young adults with frontal lobe epilepsy (mean age, 30 years) were investigated with histological/immunohistochemical markers for cortical laminar architecture, mammalian target of rapamycin pathway activation and inhibition, cellular autophagy, and synaptic vesicle-mediated trafficking as well as proteomics analysis...
October 20, 2016: Annals of Neurology
Rong-Hua Yang, Shao-Hai Qi, Shu-Bin Ruan, Ze-Peng Lin, Yan Lin, Feng-Gang Zhang, Xiao-Dong Chen, Ju-Lin Xie
Epidermal growth factor (EGF)-like family members mediate a wide range of biological activities including cell proliferation and migration. Increasing evidence indicated that EGF plays an important role in the process of wound healing by stimulating fibroblast motility. The aim of this study was to see whether EGF-like domain 7 (EGFL7)-overexpressing epidermal stem cells (EGFL7-ESCs) would promote fibroblast proliferation and migration. We found that mRNA and protein levels of EGFL7 expression were significantly increased in EGFL7-ESCs...
October 20, 2016: Molecular and Cellular Biochemistry
Xiaohong Ruby Xu, Naadiya Carrim, Miguel Antonio Dias Neves, Thomas McKeown, Tyler W Stratton, Rodrigo Matos Pinto Coelho, Xi Lei, Pingguo Chen, Jianhua Xu, Xiangrong Dai, Benjamin Xiaoyi Li, Heyu Ni
Platelets are central mediators of thrombosis and hemostasis. At the site of vascular injury, platelet accumulation (i.e. adhesion and aggregation) constitutes the first wave of hemostasis. Blood coagulation, initiated by the coagulation cascades, is the second wave of thrombin generation and enhance phosphatidylserine exposure, can markedly potentiate cell-based thrombin generation and enhance blood coagulation. Recently, deposition of plasma fibronectin and other proteins onto the injured vessel wall has been identified as a new "protein wave of hemostasis" that occurs prior to platelet accumulation (i...
2016: Thrombosis Journal
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