Thionins (THs) are a series of plant proteins with low molecular weight which can be found in higher plants’ organs such as leaves, seeds and roots. During growth, plants are inevitable to be affected by external pathogens, so higher plants evolve special defense mechanism to restrain growth and dispersion of pathogens where THs play role as peptide antibiotics to be toxic and protect plants from harmful fungi and bacteria.1 However, THs are also toxic to animal cells.2 THs can attack cells by insertion into DNA helix structure or interaction with proteins. Thus, THs’ structure and biological mechanism of interactions need to be studied. Here, I will study whether TH molecules can interact with human serum albumin (HSA).
1. Materials
TH peptides generally consists of 45-54 amino acids residues, and can be classified into five types according to numbers of amino acid residues and charges of molecules which are found in different plants tissues, but share highly sequence homology.3 Crambin which is a type IV TH may interact with HSA.4
2. Methods
2.1 Circular Dichroism (CD)
First, as a peptide, TH is a kind of chiral molecule. Therefore, its secondary structure can be measured by Circular Dichroism (CD) which can be used to characterize the protein structural information such as the proportions of α-helix and β-sheet or random coil (Equation 1). θm(λ)=aθα-helix + bθβ-sheet + cθrc (1)
The structure of THs is studied in room temperature solution. The TH sample will be dissolved in ultrapure water (blank) and loaded into quartz colorimetric cell (cell length 1.0 cm). The sample will be scanned at range from 200 to 260 nm wavelength for three times. After convert y-axis into mean residue ellipticity, my expectation is that we can o...
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...lifetimes of the donor in the presence and absence of the acceptor, respectively. Thus, according to the measurement and calculation above, it is hopeful to obtain the specific distance between TH and HSA molecule when they bind together.
In summary, THs’ structure can be determined by two methods above. What’s more, we can also use X-ray to study its three-dimensional structure in crystals, use Raman spectra, to see the existence of R-S-S-R whose strong peak on spectra near 539 cm-1. we can apply three dimensions 15N-1H-HSQC-NOESY which can use to extract distance information, residual coupling and solve groups on the peptide or on side-chains. THs are toxic to fungi and bacteria, because of the interaction with target cell membrane leading to increasing permeability of cell membrane.8 Structural studies are useful to figure out their detailed interaction mechanism
The analyzed yellow#5 wavelength was determined to 395nm because the actual wavelength 427nm was restricted in the Micro lab. The R2 value of the graph is 0.9827, and the level of data accuracy it indicated extremely weak data correlation. The first one dilution data points excluded from the standard curve because the point is not in the linear curve. The first concentration and absorbance value are the highest point in the graph that cannot connect as linear with another data point. After removing the first data point, the standard curve is clear and make
Physical Chemistry Laboratory Manual, Physical Chemistry Laboratory, Department of Chemistry, University of Kentucky, Spring 2006.
The primary structure is the sequence of amino acids that make up a polypeptide chain. 20 different amino acids are found in proteins. The exact order of the amino acids in a specific protein is the primary sequence for that protein. [IMAGE] [IMAGE]Protein secondary structure refers to regular, repeated patterns of folding of the protein backbone. The two most common folding patterns are the alpha helix and the beta sheet.
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...
Due to the nature of amino acids, a titration curve can be employed to identify
“This knowledge will help us design drugs that mimic the viral effects on these proteins to either activate a host’s immune response or shut it down,” said Dr. Michael Gale, associate ...
"The Species of the Secondary Protein Structure. Virtual Chembook - Elmhurst College. Retrieved July 25, 2008, from http://www.cd http://www.elmhurst.edu/chm/vchembook/566secprotein.html Silk Road Foundation. n.d. - n.d. - n.d.
Another advantage of GM crops is the increased insect resistance from the use of pesticides. The first and best known example is the various sub-species of the bacterium ‘Bacillus thurnigenesis’. As mentioned earlier, these produce crystalline proteins, otherwise known as ‘-endotoxins’ or ‘cry proteins’ (Ellis et al, 2002). These endotoxins attack the digestive tract of the insect.
For example, some of the proteins contain pleckstrin homology domains that bind phosphoinositide and others contain C2 domains that bind membrane lipids in the presence of Ca2+, some proteins contain positively charged regions that bind to negatively charged phosphoglycerides and others contain covalently attached fatty acyl groups or prenyl groups that anchor them to membranes. Another example is Annexin shows Ca2+ dependent binding to the cytosolic surfaces of cell membranes. Ca2+ ions bind to the iface of each annexin and this promote protein–lipid interactions through a combination of electrostatic and hydrophobic mechanisms. The same result has been shown by crystallographic studies with phosphoglyceride analogs, suggested that some of the bound Ca2+ ions may bind directly to the oxygens of phospholipid head groups. Addition to this, adjacent membrane lipids that do not bind proteins directly may modulate the protein–lipid interactions, the binding of proteins to membrane surfaces may promote further changes in the structure and function of the proteins, and groups of proteins that bind to the same membrane surface may interact with each other to produce complex membrane
The elongation cycle is highly conserved across all kingdoms of life. Each cycle of elongation adds one amino acid to the C-terminus of the newly synthesized peptide (Yu et al., 2014). Figure 9 describes the steps involved in the elongation cycle.
Mann, M., 2013. Mind Action Series Physical Sciences 12 Textbook and Workbook. Sanlamhof: Allcopy Publishers.
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...
In the hierarchial organisation of proteins, domains are found at the highest level of tertiary structure. Since the term was first used by Wetlaufer (1973) a number of definitions exist reflecting author bias, however all of the definitions agree that domains are independently folding compact units. Domains are frequently coded by exons and therefore have specific functionality. Among the many descriptions of protein domains the two most striking and simple are " Protein evolutionary units" and "Basic currency of Proteins".
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/