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Download L and D isomers of amino acids
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L and D isomers of amino acids Ionization state as a function of pH • Trans and cis • Peptide bonds • Trans and cis X-Pro • Peptide bonds Rotation about bonds in a polypeptide Ramachandran diagram a-helix Ferritin, an iron-storage protein Antiparallel -sheet A parallel -sheet A fatty acid-binding protein A leucine-zipper Collagen triple helix Collagen helix Hemoglobin Many sequences can adopt alternative conformations in different proteins. Misfolding and aggregation • Neurological diseases can be transmitted purely by proteins • Bovine spongiform encephalopathy (mad cow disease) • Creutzfeldt-Jakob disease (CJD) in humans, Scrapie in sheep (Nobel prize in Physiology 1997) Prion diseases • Transmissible agent consists of aggregated forms of a specific protein. • The protein aggregates are resistant to treatment with agents that degrade most proteins • The protein is lagely or completely derived from a cellular protein, called PrP, that is normally present in brain Prion aggregation A structure of amyloid fibers Ribose and deoxyribose Backbones of DNA and RNA • The human genome 3 billion nucleotides 24 different chromosomes • Indian muntjak, 3 chromosomes A prokaryotic and an eukaryotic cell Gene expression
