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Modeling Biomolecules Using the WWW. Major Classes of Biomolecules. Peptides (Proteins) Carbohydrates Nucleic Acids Lipids. Modeling Peptides. Primary structure
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Major Classes of Biomolecules • Peptides (Proteins) • Carbohydrates • Nucleic Acids • Lipids
Modeling Peptides • Primary structure • Most molecular modeling software allows construction of peptide models by appending pre-constructed amino acids in sequence, usually by selecting their 1- or 3-letter abbreviations. • Secondary structure • features such as a-helix, b (pleated) sheet, hairpin turns, etc. can be specified (examples on following panel).
Hairpin Turn Secondary Structure Hairpin turn, alpha helix Hairpin turn, Beta sheet
Modeling Peptides... • Tertiary structure • folding of chains…more difficult to model accurately, unless structure is known from X-ray or NMR. • Quaternary structure • Combination of several subunits...likewise difficult to model accurately, unless structure is known from X-ray or NMR.
Modeling Peptides... • Computations are usually limited to molecular mechanics, although semi-empirical MO calculations can be performed on small biopolymers. • MM Forcefields designed for biomolecules: • Amber (peptides and nucleic acids)/Kollman • OPLS (peptides and nucleic acids)/Jorgensen • BIO+ (biomacromolecules)/Karplus (all of these are found in HyperChem)
HyperChem • Special database for Peptides • 20 Pre-optimized amino acids • Peptide menu choices • a helix • b (pleated) sheet • other • Termination modes: • NH2 or NH3+; CO2H or CO2-
Spartan • Special database for Nucleotides • 4 Pre-optimized bases (A,T,C,G) • Nucleotide menu choices • DNA (double strand), DNA (single strand) • RNA (double strand), RNA (single strand) • DNA-RNA mixed • A, B or Z helical forms (differ in rise/base)
WWW pages dealing with Modeling Biomolecules • Georgia State University molecular modeling site: modeling problems, biomolecules: http://heme.gsu.edu/glactone/ • Dr. Barry Honig’s web site (Columbia University… great images of biomolecules):http://wiki.c2b2.columbia.edu/honiglab_public/index.php/Main_Page
WWW pages dealing with Modeling Biomolecules... • Molecular Graphics (rendering); University of Geneva, Switzerland (Dr. Jacques Weber) http://scsg9.unige.ch/fln/eng/toc.html • NIH Center for Molecular Modelinghttp://cmm.info.nih.gov/modeling/
WWW pages dealing with Modeling Biomolecules... • Molecular Modeling Research Group at the Dept. of Agricultural Environmental Sciences and Food Biotechnology, University of Sassari - ITALY:http://antas.agraria.uniss.it • The Research Collaboratory for Structural Bioinformatics (PDB database of structures of proteins and other biomolecules):http://www.rcsb.org