PROTEINS (Polymers of Amino Acids)

20 Amino Acids Grouped by properties of their side chains Polypeptide 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 Causes: 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