The oxidation and correct formation of disulfide bonds is an important biochemical modification of many proteins. Early observations showed that disulfide bond formation proceeds much faster in vivo than in vitro, suggesting the existence of a catalyst for protein oxidative folding in living cells [1]. Protein disulfide isomerase (PDI, EC 5.3.4.1) is a eukaryotic oxidoreductase that catalyzes the oxidation, reduction, and isomerization of disulfide bonds in nascent polypeptides [2]. The subcellular localization and its function suggest that PDI plays a key role in the folding of proteins delivered to the secretory pathway [3]. For the protozoan parasite Entamoeba histolytica, the causative agent of human amebiasis, the accurate formation of disulfide bonds is an important biochemical modification required for the correct folding of some proteins, including proteins involved in the adhesion and destruction of human tissues. Amebic proteins such as the Gal/GalNAc-inhibitable lectin and the pore-forming peptides have disulfide bonds which are crucial for the acquisition of their active conformation [4, 5]. Thus, the identification and characterization of amebic enzymes that play key roles in protein folding is essential to understand this biochemical process and gain insight knowledge of the cell biology of this parasite. An entamoebal PDI enzyme (EhPDI) that exhibits oxidative refolding activity in vivo as well as oxidative and reductive activities in vitro has been identified [6, 7]. Structurally, EhPDI shares domain architecture with the Dictyostelium discoideum homologue, DdPDI [8], featuring two active thioredoxin domains and a D-domain (also known as Erp29c domain). Interestingly, both enzymes lack the canonical ER-retenti... ... middle of paper ... ...zolides, Exp. Parasitol. (2008) 80-88. [22] T. Kimura, Y. Hosoda, Y. Kitamura, H. Nakamura, T. Horibe, M. Kikuchi, Functional differences between human and yeast protein disulfide isomerase family proteins, Biochem. Bioph. Res. Co. 320 (2004) 359-365. [23] C.W. Gruber, M. Cemazar, B. Heras, J.L Martin, D.J. Craik, Protein disulfide isomerase: the structure of oxidative folding, Trends Biochem. Sci. 31 (2006) 455-464. [24] M.A. Ramos, R.E. Mares, P.D. Magaña, J.E. Ortega, J.M. Cornejo-Bravo, In silico identification of the protein disulfide isomerase family from a protozoan parasite, Comput. Biol Chem. 32 (2008) 66-70. [25] D.R. Boettner, C.D. Huston, A.S. Linford, S.N. Buss, E. Houpt, N.E. Sherman, W.A. Petri Jr., 2008. Entamoeba histolytica phagocytosis of human erythrocytes involves PATMK, a member of the transmembrane kinase family, PLoS Pathog. 4 (2008) e8.
Western blot has been a revolutionary technique for identifying the expression of proteins within relative molecular biological samples that shared the same ancestor. Moreover, the sensitivity and specificity of the western blot (Immunoblotting) enables it a common technique for determining specific protein levels in clinical samples. Since the antibody specific to the antigen immunospecificity), it enables the target protein to be identified. Western blotting can produce quantitative data about that protein, which in this case the difference between bands in each of the protein samples. The western blot is an analytical technique used to detect specific proteins in the given sample of tissue homogenate or extract. The proteins are then transferred to a membrane (in this case, nitrocellulose), where they are stained with antibodies specific to the target protein [1] [2].
Proteins are one of the main building blocks of the body. They are required for the structure, function, and regulation of the body’s tissues and organs. Even smaller units create proteins; these are called amino acids. There are twenty different types of amino acids, and all twenty are configured in many different chains and sequences, producing differing protein structures and functions. An enzyme is a specialized protein that participates in chemical reactions where they serve as catalysts to speed up said reactions, or reduce the energy of activation, noted as Ea (Mader & Windelspecht).
Kopp, Elizabeth, and Medzhitov, Ruslan. “A Plague on Host Defense.” The Journal of Experimental Medicine. .
Sansone, Randy A., and Lori A. Sansone. "Abstract." National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 09 Apr. 2014.
Schulman, Joshua M., and David E. Fisher. "Abstract." National Center for Biotechnology Information. U.S. National Library of Medicine, 28 Aug. 0005. Web. 24 Apr. 2014.
Sequence and structural proteomics involve the large scale analysis of protein structure. Comparison among the sequence and structure of the protein enable the identification on the function of newly discovered genes (Proteoconsult, n.d.). It consists of two parallel goals which one of the goals is to determine three-dimensional structures of proteins. Determine the structure of the protein help to modeled many other structures by using computational techniques (Christendat et al., 2000). This approach is useful in phylogenetic distribution of folds and structural features of proteins (Christendat et al., 2000). Nuclear magnetic resonance (NMR) spectroscopy is one of the techniques that provide experimental data for those initiatives. It is best applied to proteins which are smaller than 250 amino acids (Yee et al., 2001). Although it is limited by size constraints and also lengthy data collection and analysis time, it is still recommended as it can deliver strong results. There are two types of NMR which are one-dimensional NMR and two-dimensional NMR. One-dimensional NMR provides enough information for assessing the folding properties of proteins (Rehm, Huber & Holak, 2002). It also helps to identify a mixture of folded and unfolded protein by observing both signal dispersion and prominent peak. Observation in one-dimensional spectrum also obtains information on molecular weight and aggregation of molecule under investigation. In spite of this, two-dimensional NMR are used for screening that reveal structural include binding, properties of proteins. It also provides important information for optimizing conditions for protein constructs that are amenable to structural studies (Rehm et al., 2002). NMR is a powerful tool which it w...
Encyclopaedia of Molecular Cell biology and molecular medicine, Robert Meyers, 2004, Wiley (page 221/426/385/416/237/ 2224/5321/5414/8869)
Myoglobin consist of single polypeptide chain that made up of 153 amino acid and ahs a size of 18 kDa. Its three-dimensional structure was first determined by X-ray crystallography by John Kendrew in 1957. Myoglobin is a typical globular protein in that it is a highly folded compact structure with most of the hydrophobic amino acid residues buried in the interior and many of the polar residues on the surface. X-ray crystallography revealed that the single polypeptide chain of myoglobin consist of entirely of eight (labelled A-H) alpha-helical. Within a hydrophobic crevice formed by the folding polypeptide chain is the heme prosthetic group. This nonopolypepetide unit is noncovalently bound to myoglobin and is essential for the biological activity of the protein.
In this experiment the enzyme peroxidase and the substrate hydrogen peroxide were not mixed initially, instead they were both placed in separate tubes and were incubated at a specific temperature, to prevent hydrogen peroxide from undergoing any reaction with peroxidase until they both acquire the required temperature.
n.d. - n.d. Peptides and Proteins. Proteins. Retrieved July 25, 2008, from http://www.cd http://www.cem.msu.edu/reusch/VirtualText/protein2.htm Ophardt, C. E. (2003).
Proteins are considered to be the most versatile macromolecules in a living system. This is because they serve crucial functions in all biological processes. Proteins are linear polymers, and they are made up of monomer units that are called amino acids. The sequence of the amino acids linked together is referred to as the primary structure. A protein will spontaneously fold up into a 3D shape caused by the hydrogen bonding of amino acids near each other. This 3D structure is determined by the sequence of the amino acids. The 3D structure is referred to as the secondary structure. There is also a tertiary structure, which is formed by the long-range interactions of the amino acids. Protein function is directly dependent on this 3D structure.
Innate system critical main defense is the cellular component; there are several kinds of cells involved in the process. One of the crucial cells is the macrophage. ...
There are four main levels of a protein, which make up its native conformation. The first level, primary structure, is just the basic order of all the amino acids. The amino acids are held together by strong peptide bonds. The next level of protein organization is the secondary structure. This is where the primary structure is repeated folded so that it takes up less space. There are two types of folding, the first of which is beta-pleated sheets, where the primary structure would resemble continuous spikes forming a horizontal strip. The seco...
Domains may be considered to be connected units, which are to varying extents independent in terms of their structure, function and folding behaviour. Each domain can be described by its fold. While some proteins consist of a single domain, others consist of several or many. A number of globular protein chains consist of two or three domains appearing as 'lobes'. In other cases the domains may be of very different nature- for example some proteins located in cell membranes have a globular intracellular or extracellular domain distinct from that which spans the membrane.
IgA1 protease, MspA, and App have been placed within the S6-peptidase family in the MEROPS database as they share common ancestry and other features like nature, order and relative positions of their catalytic residues