Proteins Macromolecules slides 31-33 of part 1, 2-19 part 2General amino acid structure/polypeptide synthesis pg. 48, 3.11Polypeptide synthesis 3.11Slide 4The 20 amino acids 3.12The 20 amino acids 3.12The 20 amino acids 3.12Slide 8The four levels of protein structure 3.13Primary structure 3.13Secondary structure 3.13Tertiary structure 3.13Tertiary structure 3.15Quaternary structure 3.13 and 3.14Motifs and Domains 3.16Slide 16Slide 17Effect of mutations on protein structure and functionMutations and protein structure 13.15Lipids (slides 20-26)Slide 21Saturated fats 3.25aUnsaturated fats 3.25bPhospholipid structure 3.27Phospholipid bilayer in water 3.28bSteroids 3.26Macromolecules: Summary Table Table 3.1You should be able to (also see study guide):Slide 29ProteinsMacromolecules slides 31-33 of part 1, 2-19 part 2Proteins are composed of one or more polypeptides–Polypeptide = single chain (polymer) of amino acidThe monomer building blocks (subunits) of polypeptides are amino acidsHRCOOHCH2NSide chain(R group)centralcarbonPeptide bondDipeptideGeneral amino acid structure/polypeptide synthesis pg. 48, 3.11Polypeptide synthesis 3.11DipeptideAminoterminusCarboxylterminusAminoterminus(N-terminus)Carboxylterminus(C-terminus)Sidechains(R groups)BackboneIndicate everything you can about this polypeptide•Why N- and C-termini are charged•Functional groups and properties of side chains•Positions of peptide bonds•Recognize each amino acid subunitThe 20 amino acids 3.12Nonpolar amino acids: hydrophobic side chainsThe 20 amino acids 3.12Polar amino acids: hydrophilic side chainsThe 20 amino acids 3.12Electrically charged amino acids:side chains with acidic or basic functional groupsAcidic(negatively charged)Basic(positivelycharged)Polypeptide chains can be short or long•Short chains (~10-50 amino acids) often called peptides–Example: insulin, a peptide hormone, 51 amino acids•Polypeptides generally ~100-1000 amino acids–Largest: titin, a muscle protein, ~26,000 amino acids!Proteins consist of one or more polypeptides twisted, folded, and coiled into a unique shape that determines its function.The four levels of protein structure 3.13Animationsprimary secondary tertiary quaternaryPrimary structure 3.13Primary (1º) structure•unique sequence of amino acids in a polypeptide (order and length)•specified directly by the nucleotide sequence of the gene encoding the polypeptideAmino acid subunitsCarboxyterminusAminoterminus1º structure determines other levels of structureSecondary structure 3.13Secondary (2º) structure•regular, repeated pattern of coils or folds created by predictable patterns of hydrogen bonding between atoms along the polypeptide backbone (not between R groups)α-helixβ-pleated sheetTertiary structure 3.13Tertiary (3º) structure•the overall three-dimensional shape of a polypeptide•Results from interactions between side chains (R groups)Tertiary structure 3.15Side-chain interactions contributing to tertiary structureMistake in text!Disulfide bridgeIonicbondHydrophobicInteractionsHydrogenbondDisulfide bondHydrophobic interactionPolypeptide backboneHydrogenbondIonicbondhttp://www.dynamicscience.com.au/tester/solutions1/chemistry/foodchemistry/proteins1.htmQuaternary structure 3.13 and 3.14Quaternary (4º) structure: the overall protein structure resulting from interaction between two or more polypeptides (subunits)HemoglobinHeme groupBeta (β)chainsAlpha (α)chainsMotifs and Domains 3.16Motif: small regions in different proteins with common structural features Domain: discrete functional unit of a protein. Most proteins have multiple domainsDomain 3Domain 2 Domain 1 Helix-turn-HelixmotifEffects of chemical and physical conditions on protein structureDenaturationRenaturation (refolding)Denatured proteinProperly foldedproteinHigh or low pHHigh temperatureNonpolar solventsDenaturation: unraveling of a protein, loss of tertiary structureIn cells, protein folding and refolding is assisted by chaperone proteins: proteins that assist in the proper folding of other proteins (Fig. 3.17).Tertiary structure (overall shape) depends on chemical and physical conditions as well as amino acid sequenceEffects of chemical and physical conditions on protein structureEffect of pHLow pH(High [H+])Neutral pHHigh pH(Low [H+])IonicbondH2Effect of mutations on protein structure and functionLight bodyDark points (extremities)Extremities(cool)Active enzyme, melanin producedTorso (warm)Enzyme denatured, no melaninDue to a mutation in gene coding for tyrosinase: an enzyme required for synthesis of melanin (dark pigment). Enzyme more sensitive to elevated temperaturetyrosinaseMutations and protein structure 13.15PrimarystructureSecondaryand TertiarystructuresQuaternarystructureNormal hemoglobinValHisLeuThr Pro Glu Gluaab subunitSickle-cell hemoglobinValHisLeuThr Pro Val GluaaSickle-cellhemoglobinExposedhydrophobicregionb subunitMutations affecting primary structure often affect other levels of structure. Example sickle-cell anemia: a mutation in hemoglobinNormalcellSicklecellLipids (slides 20-26)Lipids•do not form polymers •highly diverse in form and function •unifying feature: have little or no affinity for water (insoluble in water)–composed mostly of hydrocarbons, which form nonpolar covalent bonds–few polar groups to make them soluble in water-- mostly hydrophobic•most biologically important lipids: fats, phospholipids, and steroids, terpenesTriacylglycerol 3.25Fats = Triacylglycerol •Major function--energy storage•Constructed from glycerol and fatty acidsTriacylglycerol (Triglyceride)GlycerolFatty acid+Fatty acid tails can besaturated or unsaturatedSaturated fats 3.25aFats made from saturated fatty acids •are saturated fats•are solid at room temperature because fatty acid tails pack tightly•may contribute to cardiovascular disease through plaque deposits•include most animal fatsUnsaturated fats 3.25bFats made from unsaturated fatty acids •are unsaturated fats•are liquid at room temperature because fatty acid tails are kinked•are also called oils•include most fats (oils) from plants and fishhttps://www.youtube.com/watch?v=ESPNqKUluRsPhospholipids--major component of cell membranes‒glycerol backbone‒two fatty acid tails‒one phosphate groupPhospholipid structure 3.27Polar HydrophilicHead GroupsNonpolar HydrophobicTailsAmphipathic: part hydrophilic and part hydrophobic--partly having an affinity for water and