Download Understanding Proteins: Structure, Function, and Types and more Slides Biology in PDF only on Docsity! Chapter 5c: The Structure and Function of Macromolecules (Proteins) Docsity.com Polymers, Monomers, and Lipids polymer category of biomolecules monomer polysaccharide carbohydrates monosaccharides polypeptides proteins amino acids polynucleic acids RNA & DNA nucleotides Docsity.com A m in o A ci d S tru ct ur e The chemistry of R groups distinguishes amino acids and their properties Docsity.com A m in o A ci d Ty pe s Name R-Group Properties Glycine G Gly Hydrophobic Alanine A Ala Hydrophobic Valine V Val Hydrophobic Leucine L Leu Hydrophobic Isoleucine I Ile Hydrophobic, two chiral carbons Proline P Pro Cyclic, not terribly hydrophobic Phenylalanine F Phe Hydrophobic, bulky Tyrosine Y Tyr Less hydrophobic (than Phe), bulky Tryptophan W Trp Hydrophobic, bulky (indole ring) Cysteine C Cys Hydrophobic, highly reactive (S-S link) Methionine M Met Hydrophobic (start a.a.) Serine S Ser Hydrophilic, reactive Threonine T Thr Hydrophilic, reactive, two chiral carbons Lysine K Lys Highly hydrophilic, positively charged Arginine R Arg Highly hydrophilic, positively charged Histidine H His Highly hydrophilic, positive or neutral Aspartate D Asp Highly hydrophilic, negatively charged Glutamate E Glu Highly hydrophilic, negatively charged Asparagine N Asn Uncharged Glutamine Q Gln Uncharged Docsity.com OH
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B ac kb on e R ig id ity Because of Resonance the backbone of polypeptides has greater rigidity than otherwise might be expected Polypeptide backbones are more than just wet noodles! Docsity.com P ro te in D ep ic tio n (4 w ay s) Conformation = Shape Function The surface chemistry of a protein is determined by the chemistry of exposed amino- acid R groups The interior of proteins is held together by R- group-to-R- group and backbone-to- backbone interactions Docsity.com Protein Primary Structure 1’ structure = ordered sequence of amino acids Docsity.com P ro te in T er tia ry S tru ct ur e Tertiary structure is controlled by the interactions between non-adjacent amino acid R groups (note bond types) Docsity.com P ro te in Q ua te rn ar y S tru ct ur e Quaternary structure is the interaction between adjacent polypeptides that make up a single protein Note that the polypeptides reside in discrete subunits rather than being tangled together like spaghetti Docsity.com P ro te in S tru ct ur e O ve rv ie w “’Polypeptide’ is not quite synonymous with ‘protein.’ The relationship is somewhat analogous to that between a long strand of yarn and a sweater of a particular size and shape that one can knit from the yarn. A functional protein is not just a polypeptide chain, but one or more polypeptides precisely twisted, folded, and coiled into a molecule of unique shape. It is the amino-acid sequence of a polypeptide that determines what three-dimensional conformation the protein will take.” (p. 70, Campbell et al., 1999) (see p. 81 of 2005 edition) Docsity.com
