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Stability engineering

Gitte Brinch Andersen, Jörg Tost
DNA methylation at cytosines followed by guanines, CpGs, forms one of the multiple layers of epigenetic mechanisms controlling and modulating gene expression through chromatin structure. It closely interacts with histone modifications and chromatin remodeling complexes to form the local genomic and higher-order chromatin landscape. DNA methylation is essential for proper mammalian development, crucial for imprinting and plays a role in maintaining genomic stability. DNA methylation patterns are susceptible to change in response to environmental stimuli such as diet or toxins, whereby the epigenome seems to be most vulnerable during early life...
2018: Methods in Molecular Biology
Fatima Ahsan, Qurratulann Afza Gardner, Naeem Rashid, Greg J Towers, Muhammad Akhtar
We have previously shown that human interferon α-2b (IFN) produced in Escherichia coli (E. coli) is heterogeneous at the N-terminal, with three major species (Ahsan et al., 2014). These are: (a) the direct translation product of the gene retaining the N-terminal methionine, (b) a species from which the methionyl residue has been removed by E. coli methionyl aminopeptidase to give the native interferon α-2b and (c) in which the N-terminal Cys residue of the latter contains an acetyl group. In this paper we overcome this heterogeneity, using engineered interferon derivatives with phenylalanine residue directly downstream of the N-terminal methionine (Met-Phe-IFN)...
November 23, 2017: Bioorganic Chemistry
Zhicheng Zuo, Jin Liu
The bacterial CRISPR-Cas9 immune system has been harnessed as a powerful and versatile genome-editing tool and holds immense promise for future therapeutic applications. Despite recent advances in understanding Cas9 structures and its functional mechanism, little is known about the catalytic state of the Cas9 HNH nuclease domain, and identifying how the divalent metal ions affect the HNH domain conformational transition remains elusive. A deeper understanding of Cas9 activation and its cleavage mechanism can enable further optimization of Cas9-based genome-editing specificity and efficiency...
December 8, 2017: Scientific Reports
Dinh Loc Duong, Seok Joon Yun, Young Hee Lee
Since graphene became available by a scotch tape, a vast class of two-dimensional (2D) van der Waals (vdW) layered materials has been researched intensively. What is more intriguing is that the well-known physics and chemistry of three-dimensional bulk materials are often irrelevant, revealing exotic phenomena in 2D vdW materials. By further constructing heterostructures of these materials in the planar and vertical directions, which can be easily achieved via simple exfoliation techniques, numerous quantum mechanical devices have been demonstrated for fundamental research and technological applications...
December 8, 2017: ACS Nano
S Beg, Jaya Agnihotri, Shibhna Singh, Mohammad Wais
Newly developed vaccine VPM1002 confers paradigm swing in the prophylactic treatment of tuberculosis (TB).Multi drug resistant and latent TB in adults as well as in underprivileged patients is instigating menace over world population if the host is immune-compromised. One third of the world's population is infected with TB. Recently it is estimated around 9.6 million people around the world became sick with TB disease. There were 1.5 million TB-related deaths worldwide. Therefore with the advent in biotechnology and Nano engineering, newly adapted survival molecular mechanism of Mycobacterium tuberculosis, new targets receptors on alveolar macrophages must be explored out for eradication of TB from the globe...
December 7, 2017: Recent Patents on Anti-infective Drug Discovery
Monica Jara Avaca, Ina Gruh
Engineered cardiac tissue might enable novel therapeutic strategies for the human heart in a number of acquired and congenital diseases. With recent advances in stem cell technologies, namely the availability of pluripotent stem cells, the generation of potentially autologous tissue grafts has become a realistic option. Nevertheless, a number of limitations still have to be addressed before clinical application of engineered cardiac tissue based on human stem cells can be realized. We summarize current progress and pending challenges regarding the optimal cell source, cardiomyogenic lineage specification, purification, safety of genetic cell engineering, and genomic stability...
December 8, 2017: Advances in Biochemical Engineering/biotechnology
Caitlyn L McCafferty, Yuri V Sergeev
A protein's amino acid sequence dictates the folds and final structure the macromolecule will form. We propose that by identifying critical residues in a protein's atomic structure, we can select a critical stability framework within the protein structure essential to proper protein folding. We use global computational mutagenesis based on the unfolding mutation screen to test the effect of every possible missense mutation on the protein structure to identify the residues that cannot tolerate a substitution without causing protein misfolding...
2017: PloS One
Akalabya Bissoyi, Abhishek Kumar Singh, Subrat Kumar Pattanayak, Arindam Bit, Sudip Kumar Sinha, Ashish Patel, Vishal Jain, Pradeep Kumar Patra
The development of engineered bone tissue, as a promising alternative to conventional bone grafts, has so far not proven successful and still remains challenging. Thus, attempts have been made in the present study to synthesize polyelectrolyte complex (PEC) scaffolds by blending chitosan (CS) to silk fibroin (SF) derived from the non-mulberry silkworm (Antheraea pernyi) at three different pH values (5.0, 6.0, and 7.0), and to characterize them in terms of morphology, ultrastructure and mechanical properties with scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy, x-ray diffraction and tensile strength analyses...
December 7, 2017: Biomedical Materials
Zheng Zhou, Min Li, Jian-He Xu, Zhi-Jun Zhang
Nitrile reductase is considered as a promising and environmentally benign nitrile-reducing biocatalyst to replace traditional metal catalysts. Unfortunately, the catalytic efficiencies of nitrile reductases reported so far are very low. To date, any attempts by protein engineering to increase the catalytic activity of nitrile reductase have failed. In this work, we successfully increased the specific activity of a nitrile reductase from Pectobacterium carotovorum from 354 U·gprot-1 to 526 U·gprot-1 by engineering the substrate binding pocket, meanwhile the thermostability was also improved (ca...
December 7, 2017: Chembiochem: a European Journal of Chemical Biology
Sheng Zeng, Piyush Kar, Ujwal Kumar Thakur, Karthik Shankar
As the search for efficient catalysts for CO2 photoreduction continues, nanostructured perovskite oxides have emerged as a class of high-performance photocatalytic materials. The perovskite oxide candidates for CO2 photoreduction are primarily nanostructured forms of titanates, niobates, tantalates and cobaltates. These materials form the focus of this review article because they are much sought-after due to their nontoxic nature, adequate chemical stability, and tunable crystal structures, bandgaps and surface energies...
December 7, 2017: Nanotechnology
Kyle Sander, Keiji G Asano, Deepak Bhandari, Gary J Van Berkel, Steven D Brown, Brian Davison, Timothy J Tschaplinski
Background: Clostridium thermocellum and Thermoanaerobacterium saccharolyticum are prominent candidate biocatalysts that, together, can enable the direct biotic conversion of lignocellulosic biomass to ethanol. The imbalance and suboptimal turnover rates of redox cofactors are currently hindering engineering efforts to achieve higher bioproductivity in both organisms. Measuring relevant intracellular cofactor concentrations will help understand redox state of these cofactors and help identify a strategy to overcome these limitations; however, metabolomic determinations of these labile metabolites have historically proved challenging...
2017: Biotechnology for Biofuels
Peter Bannas, Julia Hambach, Friedrich Koch-Nolte
Monoclonal antibodies have revolutionized cancer therapy. However, delivery to tumor cells in vivo is hampered by the large size (150 kDa) of conventional antibodies. The minimal target recognition module of a conventional antibody is composed of two non-covalently associated variable domains (VH and VL). The proper orientation of these domains is mediated by their hydrophobic interface and is stabilized by their linkage to disulfide-linked constant domains (CH1 and CL). VH and VL domains can be fused via a genetic linker into a single-chain variable fragment (scFv)...
2017: Frontiers in Immunology
Hongbo Yuan, Jialiang Xu, Eliane P van Dam, Giulia Giubertoni, Yves L A Rezus, Roel Hammink, Huib J Bakker, Yong Zhan, Alan E Rowan, Chengfen Xing, Paul H J Kouwer
Enhancing the thermal stability of proteins is an important task for protein engineering. There are several ways to increase the thermal stability of proteins in biology, such as greater hydrophobic interactions, increased helical content, decreased occurrence of thermolabile residues, or stable hydrogen bonds. Here, we describe a well-defined polymer based on β-helical polyisocyanotripeptides (TriPIC) that uses biological approaches, including hydrogen bonding and hydrophobic interactions for its exceptional thermal stability in aqueous solutions...
November 28, 2017: Macromolecules
Parul Maheshwari, Réka Albert
BACKGROUND: Cellular behaviors are governed by interaction networks among biomolecules, for example gene regulatory and signal transduction networks. An often used dynamic modeling framework for these networks, Boolean modeling, can obtain their attractors (which correspond to cell types and behaviors) and their trajectories from an initial state (e.g. a resting state) to the attractors, for example in response to an external signal. The existing methods however do not elucidate the causal relationships between distant nodes in the network...
December 6, 2017: BMC Systems Biology
M Gordon Joyce, Ivelin S Georgiev, Yongping Yang, Aliaksandr Druz, Hui Geng, Gwo-Yu Chuang, Young Do Kwon, Marie Pancera, Reda Rawi, Mallika Sastry, Guillaume B E Stewart-Jones, Angela Zheng, Tongqing Zhou, Misook Choe, Joseph G Van Galen, Rita E Chen, Christopher R Lees, Sandeep Narpala, Michael Chambers, Yaroslav Tsybovsky, Ulrich Baxa, Adrian B McDermott, John R Mascola, Peter D Kwong
The elicitation of autologous neutralizing responses by immunization with HIV-1 envelope (Env) trimers conformationally stabilized in a prefusion closed state has generated considerable interest in the HIV-1 vaccine field. However, soluble prefusion closed Env trimers have been produced from only a handful of HIV-1 strains, limiting their utility as vaccine antigens and B cell probes. Here, we report the engineering from 81 HIV-1 strains of soluble, fully cleaved, prefusion Env trimers with appropriate antigenicity...
December 5, 2017: Cell Reports
Nicholas West, Klaske van Heusden, Matthias Görges, Sonia Brodie, Aryannah Rollinson, Christian L Petersen, Guy A Dumont, J Mark Ansermino, Richard N Merchant
BACKGROUND: Closed-loop control of anesthesia involves continual adjustment of drug infusion rates according to measured clinical effect. The NeuroSENSE monitor provides an electroencephalographic measure of depth of hypnosis (wavelet-based anesthetic value for central nervous system monitoring [WAVCNS]). It has previously been used as feedback for closed-loop control of propofol, in a system designed using robust control engineering principles, which implements features specifically designed to ensure patient safety...
November 22, 2017: Anesthesia and Analgesia
Daichi Kato, Kenta Hongo, Ryo Maezono, Masanobu Higashi, Hironobu Kunioku, Masayoshi Yabuuchi, Hajime Suzuki, Hiroyuki Okajima, Chengchao Zhong, Kousuke Nakano, Ryu Abe, Hiroshi Kageyama
A layered oxychloride Bi4NbO8Cl is a visible-light responsive catalyst for water splitting, with its remarkable stability ascribed to the highly dispersive O-2p orbitals in the valence band, the origin of which, however, remains unclear. Here we systematically investigate four series of layered bismuth oxyhalides, BiOX (X = Cl, Br, I), Bi4NbO8X (X = Cl, Br), Bi2GdO4X (X = Cl, Br) and SrBiO2X (X = Cl, Br, I) and found that Madelung site potentials of anions capture essential features of the valence band structures of these materials...
December 6, 2017: Journal of the American Chemical Society
Dan Liu, Kun Du, Wei Feng
OBJECTIVE: To design a fusion polypeptide combining functions of self-assembly and purification for immobilizing enzymes. RESULTS: A collagen-like polypeptide (CLP) was fused to an elastin-like polypeptide (ELP) through genetic engineering. CLP-ELP was separately fused to superoxide dismutase (SOD) and D-amino acid oxidase (DAAO). The recombinant enzymes were purified with using reversible phase transition. The interfering effect of H2O2 on the secondary structures of the recombinant enzymes was significantly reduced...
December 5, 2017: Biotechnology Letters
Michele Boffano, Stefano Mortera, Hazem Wafa, Raimondo Piana
Acromioclavicular joint (ACJ) injuries are common, but their incidence is probably underestimated. As the treatment of some sub-types is still debated, we reviewed the available literature to obtain an overview of current management.We analysed the literature using the PubMed search engine.There is consensus on the treatment of Rockwood type I and type II lesions and for high-grade injuries of types IV, V and VI. The treatment of type III injuries remains controversial, as none of the studies has proven a significant benefit of one procedure when compared with another...
October 2017: EFORT open reviews
Xue-Qing Huang, Hong-Ye Yang, Tao Luo, Cui Huang, Franklin R Tay, Li-Na Niu
Strategies based on the combination of nanocarrier delivery systems and scaffolds provide bone tissue engineering scaffolds with multifunctional capability. Zirconia, a biocompatible ceramic commonly used in orthopedic and dental implants, was used to synthesize hollow mesoporous nanocapsules for loading, storage and sustained release of a novel polyamine-stabilized liquid precursor phase of amorphous calcium phosphate (PAH-ACP) for collagen biomineralization and bone marrow stromal cells osteoinduction. Hollow mesoporous zirconia (hmZrO2) nanocapsules loaded with biomimetic precursors exhibited pH-sensitive release capability and good biocompatibility...
December 2, 2017: Acta Biomaterialia
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