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Search Results: 1 - 10 of 11325 matches for " protein "
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Some No Longer Unknowns in Science  [PDF]
Arieh Ben-Naim
Open Journal of Biophysics (OJBIPHY) , 2012, DOI: 10.4236/ojbiphy.2012.21001
Abstract: Three out of 125 “big questions of science”, can now be claimed to have been answered. All of these questions involve water; its structure, its role in protein folding and its role in protein-protein association.
Preliminary study of binary protein adsorption system and potential bioseparation under homogeneous field of shear in airlift biocontactor  [PDF]
Yaser Dahman, Kithsiri E. Jayasuriya
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.46094

This paper investigates the bioseparation of binary protein mixtures using polystyrene based anion exchange resin. Adsorption experiments were conducted in batch mode using draft-tube internally recirculate dair lift biocontactor in comparison with the conventional shake flask batch adsorption equilibrium experiments. Binary protein mixtures contained bovine serum albumin (BSA) and bovine haemoglobin (BHb) at different initial fractions. Results from single solute adsorption experiments in biocontactor showed that both proteins were equally adsorbed onto the resin with equilibrium reached in an equal time period. This represents similar affinities towards the negatively charged resin surface, although BSA was expected to adsorb through specific forces. Adsorption results showed that BSA has hindered the BHb adsorption in the biocontactor, although adsorption of both proteins was equally hindered in the shake flasks adsorption experiments. Moreover, adsorption of BHb was inhibited up to 29% in the presence of BSA compared to the adsorption of BHb from a solution containing single solute of BHb at the same initial concentration. Similarly, the presence of BHb has hindered the adsorption of BSA by 59%. Adsorptions of both BSA and BHb from binary solution when each formed 75% initial fraction while the other protein formed the remaining 25% were relatively low with equilibrium reached in shorter time. Moreover, considerable amount of proteins remained in the solution, which demonstrates that multilayer adsorption most likely didn’t occur at the relatively small protein concentrations used in the present study. In general, the higher adsorption of BHb can also be related to the compressibility of its molecules which allowed for higher adsorption capacity. The homogeneous and lower shear environment in the airlift biocontactor compared to the other conventional batch adsorption in shake flask reduced the compressibility of BHb that caused higher BSA adsorption from binary solutions of BSA and BHb, which allowed for better bioseparation of both proteins.

Inteins—A Focus on the Biotechnological Applications of Splicing-Promoting Proteins  [PDF]
Manfredi Miraula, Charmaine Enculescu, Gerhard Schenk, Nata?a Miti?
American Journal of Molecular Biology (AJMB) , 2015, DOI: 10.4236/ajmb.2015.52005
Abstract: The main aim of this mini-review is to illustrate strategies and industrial applications based on inteins (INTErnal proteINS), which belong to a class of autocatalytic enzymes that are able to perform a catalytic reaction on a single substrate. However, since practical applications of inteins are strongly guided by a detailed understanding of their biological mechanisms and functions, the first part of this review will thus briefly discuss the physiological roles of inteins, describing what is currently known about their mechanisms of action. In the second part, specific biotechnological applications of inteins will be outlined (i.e. their use for (i) the purification of recombinant proteins, (ii) the cyclization of proteins and (iii) the production of seleno-proteins), paying attention to both potential strengths and weaknesses of this technology.
Development and Applications of a Calmodulin-Based Fusion Protein System for the Expression and Purification of WW and Zinc Finger Modules  [PDF]
Christopher G. Toomey, David Weiss, Alan Chant, Megan Ackerman, Bethany A. Ahlers, Ying-Wai Lam, Christopher Ricciardi, Dana Bourne, Christina M. Kraemer-Chant
Advances in Biological Chemistry (ABC) , 2017, DOI: 10.4236/abc.2017.72006
Abstract: Calmodulin from Homo sapiens is an α-helical calcium-binding protein that expresses to high levels in E. coli. When the N-terminus of a calmodulin variant is bound to Ca2+, it undergoes a conformational change, exposing hydrophobic pockets. This property can be utilized for purification purposes, as these pockets bind to phenyl sepharose resin with high affinity. Washing with EDTA chelates the Ca2+ ions from the protein, inducing a conformational change back to the more folded state and eluting the protein from the column. We describe herein the use of a protein expression and purification technique using the calmodulin variant and a short linker for proteolytic cleavage by the mutant NIa-Pro tobacco etch virus protease. We have shown this approach to be useful in obtaining purified quantities of various small proteins that could not be expressed using other methods, including high enough concentrations of a designed WW domain protein for NMR structural analysis. We have also obtained promising results on the usefulness of this procedure to express and purify zinc finger proteins without the addition of zinc ions or other cofactors.
The Functions of the Amyloid Precursor Protein Gene and Its Derivative Peptides: I Molecular Biology and Metabolic Processing  [PDF]
Peter K Panegyres, Emily R Atkins
Neuroscience & Medicine (NM) , 2011, DOI: 10.4236/nm.2011.22018
Abstract: The amyloid precursor protein gene (APP) and its derivative peptides have important functions in the central nervous system. APP and Aβ fulfil criteria as neuractive peptides: presence, release and identity of action. Aβ is a peptide of 1 - 43 amino acids in length, derived from APP and the major component of the core of neuritic plaques found in Alzheimer’s disease. Analysis of the cDNA of Aβ revealed its origins from the larger precursor protein. There are at least four types of mRNA generated by alternative splicing of exons 7 and 8. Exon 7 encodes a 57 amino acid sequence found in the extracellular domain with major homology to the Kunitz-type of serine protease inhibitors. APP is cleaved by three secretases known as α, β, and γ secretase which act on APP at different sites producing various fragments of differing amino acid length. The γ secretase is a macromolecular enzyme complex composed of presenilin 1, 2 and other molecular constitutents essential for its function.
The Functions of the Amyloid Precursor Protein Gene and Its Derivative Peptides: II Experimental Evidence and Clinical Studies  [PDF]
Peter K. Panegyres, Emily R. Atkins
Neuroscience & Medicine (NM) , 2011, DOI: 10.4236/nm.2011.23033
Abstract: In vitro studies suggest Amyloid Precursor Protein Gene (APP) is involved in interaction with the extracellular matrix, neurite growth, adhesion, development, synaptic function, platelet function, and interaction with GTP binding proteins. In vivo experiments show a role in embryonic development, response to cerebral excitotoxicity and gliosis, response to brain injury including ischaemia, hypothalamic function, locomotor function, learning and memory. In vitro observations indicate Aβ has a role in amyloid formation, excitotoxic neuronal injury, tachykinin interaction, endothelial vasoconstrictor response, calcium and oxidative stress, free radical interaction, cell membrane fluidity, apoptosis, astrocyte stimulation, and microglial interaction. Other studies suggest important roles for Aβ oligomers in synaptic function and as an antimicrobial peptide. In vivo investigations show involvement in memory function, the blood brain barrier, and tachykinin response to cerebral injury.
Prot-Class: A bioinformatics tool for protein classification based on amino acid signatures  [PDF]
Jens Lichtenberg, Brian D. Keppler, Thomas Conley, Dazhang Gu, Paul Burns, Lonnie R. Welch, Allan M. Showalter
Natural Science (NS) , 2012, DOI: 10.4236/ns.2012.412A141

Knowledge about characteristics shared across known members of a protein family enables their identification within the complete set of proteins in an organism. Shared features are usually expressed through motifs, which can incorporate specific patterns and even amino acid (AA) biases. Based on a set of classification patterns and biases it can be determined which additional proteins may belong to a specific family and share its functionality. A bioinformatics tool (Prot-Class) was implemented to examine protein sequences and characterize them based upon user-defined AA composition percentages and user defined AA patterns. In addition the tool allows for the identification of repeated AA patterns, biased AA compositions within windows of user-defined length, and the characteristics of putative signal peptides and glycosylphosphatidylinositol (GPI) lipid anchors. ProtClass is general purpose and can be applied to analyze protein sequences from any organism. The Prot-Class source code is available through the GNU General Public License v3 and can be accessed via the Google Code Repository: http://code.google.com/p/prot-class/.

Comment on a Paper: “Ben-Naim’s ‘Pitfalls’: Don Quixote’s Windmill”, by Y. Fang, Open Journal of Biophysics, 2013, 3, 13-21  [PDF]
Arieh Ben-Naim
Open Journal of Biophysics (OJBIPHY) , 2013, DOI: 10.4236/ojbiphy.2013.34032

This article is a response to Fangs article which criticizes statements never made by Ben-Naim and never appeared in the literature.

A Comparative Study of Present Status of Marketing of Formalin Treated Fishes in Six Districts of Bangladesh  [PDF]
Rafiad Islam, Shahin Mahmud, Abdul Aziz, Animesh Sarker, Marufa Nasreen
Food and Nutrition Sciences (FNS) , 2015, DOI: 10.4236/fns.2015.61013
Abstract: The fish is an important food stuff and source of protein all over the world. In Bangladesh, fisheries sector contributes a lot, in the case of the earning foreign currency and meeting domestic need of the animal proteins. To fulfill the domestic need of protein and fish, Bangladesh imports fish and fish products from the neighboring county. In many studies, it was proved that most of the imported fishes are contaminated with formalin, which is the highly hazardous and carcinogenic chemical. Information was collected from the fish retailers and consumers on the marketing of the formalin treated fishes through survey using prescribed questionnaire at 18 different fish markets in 6 different districts of Bangladesh. It was found that most of the commercially imported fishes are highly contaminated with formalin. On the other hand, local big fishes, such as rui (Lobeo Rohita), catla (Catla catla) and mrigal (Cirrhinus cirrhosus) etc., are also formalin contaminated partially, but not all the fishes. All the local small fishes are free from the formalin contamination. In this study, it was found that, among the 939 fish samples collected from the different fish markets of the six districts, 213 fishes (22.68%) were directly contaminated with formalin. The contamination rate is so much higher in the big city like Dhaka (36.78%) and lower in the small town like Jamalpur districts (13.33%). This study also indicated that, all the village markets were totally free from the formalin contamination. As the fish traders used formalin to increase the shelf life of the fishes, it was also observed that, the shelf life of the local fishes or formalin free fishes was much higher and the organoleptic characteristics were much more excellent than the formalin contaminated local or imported fishes. The price of the imported fishes was also lower than the local fishes. It was also clear that, the organoleptic characteristics of the imported fishes and formalin contaminated fishes were greatly different than the local fishes, which were not satisfactory to the consumers. The study also indicated that, the overall hygienic practice and sanitary conditions of the markets and the fish traders/retailers were very poor, not satisfactory. This survey also revealed that, all the traders or retailers who were mixed formalin with the fishes, knew about the bad effects of the formalin.
Determina??o de proteínas totais via espectrofometria: vantagens e desvantagens dos métodos existentes
Zaia, Dimas A. M.;Zaia, Cássia Tha?s B. V.;Lichtig, Jaim;
Química Nova , 1998, DOI: 10.1590/S0100-40421998000600020
Abstract: spectrophotometric determination of total protein is used in several areas such as clinical analysis, food science and technology, biochemistry, protein chemistry, physiology. five spectrophotometric methods are mostly used: biuret, lowry, bradford, smith and uv absorption. in this review a general overview of these methods is presented (interferences, applications); other methodologies are also discussed.
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