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Characteristics of Sugar Binding Sites of Enzymatic Proteins Probing the Spatial and Chemical Features Using SVM. Khuri S.*, Nassif H., Al-Ali Merheby H., and Keyrouz W. Why Hexoses?
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Characteristics of Sugar Binding Sites of Enzymatic Proteins Probing the Spatial and Chemical Features Using SVM Khuri S.*, Nassif H., Al-Ali Merheby H., and Keyrouz W.
Why Hexoses? 1- key players in many different biochemical pathways, including cellular energy release, signaling pathways, carbohydrate genesis and gene expression regulation. 2- Different types of proteins bind the hexoses, resulting in structure/function modification.
Why the tool? 1- Numerous proteins of unknown functions bind hexoses. 2- Many of these proteins cannot be crystallized in the bound state. 3- Being able to predict hexose binding sites might offer insight on chemical function and metabolic links between proteins. Background review on protein chemistry: 1- Aminoacid chemistry 2- Peptide Bonds 3- Primary structure of proteins 4- Protein folding ViewAnimation
Substrat specificity in binding sites Two major components: 1- Spatial specificity (Key and Lock) 2- Chemical specificity (Like Dissolves Like). Dependent on the chemical features of the atoms, not on the type of the atoms.
Purpose of the Study To characterize the spatial and chemical features of Sugar Binding sites in proteins. I- Data-mine the protein structure database (PDB) 1- Collect all structures that contain bound hexoses (Glucose, Mannose, and Galactose). 2- Classify these structures based on the type of the bound hexose, and on the nature of bonding. Covalently bonded sugars are not considered ligands. 3- Get rid of redundancies (perform multiple alignments) 4- Create a representative Data set. II- Learn the characterizing chemical features of the binding sites: Vector Machines Support (VMS) III-Apply the data on a prediction tool.
The input to the SVM is a vector of features per binding site. All input vectors should have the same number and order of features. Since the atoms/residues contained in a binding site will vary among different proteins, a layering approach will be used. The algorithm will generate a feature vector for each layer. The features include, among others, hydrophobicity, charge and elctronegativity values of the layer. An example of Sampled features (per quarter hemisphere) in Layer X
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