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PROTEINS (Polymers of Amino Acids) 20 Amino Acids • Grouped by properties of their side chains – Non-polar (hydrophobic) – Polar (hydrophilic) – Acidic (-COOH grp) – Basic (-NH2) • Polypeptide – Many amino acids linked together Types of Proteins • • • • • • • Structural – ligaments, hair, horns, webs Storage (energy) – seeds, egg whites Transportation – blood & Facillitated Diffusion Regulation – hormones: insulin & testosterone Movement/Reaction – reflex, contraction Immunology – antigens & antibodies Enzymes – speed up rxns (digestion) DENATURATION • Protein loses its shape & no longer function – More shape changes, greater impact on its ability to function • Causes: – Temperature – pH (toxic chemicals) – Radiation • Example: Sickle Cell Anemia MOLECULAR STRUCTURE • PRIMARY – Sequence of amino acids MOLECULAR STRUCTURE Single (point) mutations can cause problems Normal hemoglobin: VAL – HIS – LEU – THR – PRO – GLU – GLU Sickle Cell Hemo.: VAL – HIS – LEU – THR – PRO – VAL – GLU MOLECULAR STRUCTURE • SECONDARY – A.A. chain coil or fold due H-bonds – Alpha Helix: -- Pleated Sheets MOLECULAR STRUCTURE • TERTIARY – 3-D shape – Globular – (round clusters – hemoglobin) – Fibrous – (long threads – collegen) – Hydrophobic interaction – nonpolar sections of molecule clump to middle of protein away from any possible sources of water MOLECULAR STRUCTURE • QUATERNARY – Interaction of multiple polypeptide chains ENZYMES • Substrate – substance being broken down • Active site – area where substrate/enzyme connect • Induced Fit – slight change of shape as enzyme & substrate join Affects on Reaction Rates • Cofactors / coenzymes – an additional enzyme working on same substrate • Competitive Inhibitors – block active site Affects on Reaction Rates • Noncompetitive Inhibitors – changes shape of the enzyme without attaching to the active site • Allosteric regulation – attachment of another molecule which changes the shape of the enzyme Metabolic Controls • Feedback Inhibition – the product of the reaction binds to the enzyme & prevents it from doing its job. Avoid excess production Metabolic Controls • Cooperativity – (form allosteric regulation) when another molecule helps maintain shape of enzyme