BIO173 Biology: Proteins and Amino Acids PDF

BIO173 Biology Proteins: Amino Acids Protein  Most diverse biological macromolecule  Organic compound composed of one or more chains of Amino Acids Amino Acid Polymer SCHOOL OF BIOLOGICAL SCIENCES 2...

BIO173 Biology Proteins: Amino Acids Protein  Most diverse biological macromolecule  Organic compound composed of one or more chains of Amino Acids Amino Acid Polymer SCHOOL OF BIOLOGICAL SCIENCES 2 AND APPLIED CHEMISTRY Importance  “Proteios” = Greek for “primary” Previously called “Albumins” Cell has 9000 different Proteins Body has 100 000 different Proteins  Enzymes as Catalysts Proteins that “speed up” Chemical Reactions Carry out most the Metabolic Reactions  Cell Signaling Substrate binding to Receptors to transmit a signal Local signaling (Paracrine) Hormones for signaling throughout the body (Endocrine) SCHOOL OF BIOLOGICAL SCIENCES 3 AND APPLIED CHEMISTRY Importance  Structural Fibrous = Collagen, Elastin & Keratin Connective Tissue, Hair, Nails, Feathers, Hooves Globular = Actin & Tubulin Creates the Cells Cytoskeleton to maintain shape Motor = Myosin, Kinesin & Dynein Muscle Contraction SCHOOL OF BIOLOGICAL SCIENCES 4 AND APPLIED CHEMISTRY Importance  Transport Across cell membranes Throughout the body  Protection Antibodies Blood clotting SCHOOL OF BIOLOGICAL SCIENCES 5 AND APPLIED CHEMISTRY Structure  Composed of the Elements Carbon, Hydrogen, Oxygen, Nitrogen & Sulfur  Amino Acid is the Monomer Small organic compound Amine Group (-NH2) Carboxyl Group (-COOH) R Group R Side chain that distinguishes the properties SCHOOL OF BIOLOGICAL SCIENCES 6 AND APPLIED CHEMISTRY Amino Acid  Zwitterion Molecule having separate Positively & Negatively charged groups In water the Functional Groups will ionize Glycine (R Group = H) SCHOOL OF BIOLOGICAL SCIENCES 7 AND APPLIED CHEMISTRY Amino Acids  20 Natural Amino Acids Used by the body to make Proteins  Side Chain “R Groups” Differs in Structure & Properties  Amino Acids are classified by the properties of the R Groups Polar vs Non-Polar Acidic vs Basic vs Neutral  Three letter code assigned to each Amino Acid SCHOOL OF BIOLOGICAL SCIENCES 8 AND APPLIED CHEMISTRY Non-Polar Amino Acids  R Group atoms contains Non-Polar Covalent bonds Mostly Carbon & Hydrogen  Hydrophobic properties Repelled by Water  Amino Acids move to the Centre of Protein to avoid Water Stabilize the Proteins Structure  Longer the R-Group, the more Non-Polar the Amino Acid is SCHOOL OF BIOLOGICAL SCIENCES 9 AND APPLIED CHEMISTRY Glycine  Non-Polar  Does not have an R-Group Technically the R-Group is Hydrogen  Often found on the Surface of Proteins  Provides flexibility for loops & coils SCHOOL OF BIOLOGICAL SCIENCES 10 AND APPLIED CHEMISTRY Non-Polar Amino Acids Alanine Valine SCHOOL OF BIOLOGICAL SCIENCES 11 AND APPLIED CHEMISTRY Non-Polar Amino Acids Leucine Isoleucine SCHOOL OF BIOLOGICAL SCIENCES 12 AND APPLIED CHEMISTRY Non-Polar Amino Acids Phenylalanine Methionine SCHOOL OF BIOLOGICAL SCIENCES 13 AND APPLIED CHEMISTRY Proline  Non-Polar  Only cyclic Amino Acid  Provided rigidity for Protein Structures SCHOOL OF BIOLOGICAL SCIENCES 14 AND APPLIED CHEMISTRY Tryptophan  Non-Polar  Aromatic ring distributes the charge from Nitrogen (Resonance) Not enough Polarity to Hydrogen-bond SCHOOL OF BIOLOGICAL SCIENCES 15 AND APPLIED CHEMISTRY Cysteine  Non-Polar  The R-Group is weakly Polar Not enough Polarity to Hydrogen-bond  Cysteine forms Disulfide Bridges with each other Covalent bond in Protein Structure SCHOOL OF BIOLOGICAL SCIENCES 16 AND APPLIED CHEMISTRY Polar Amino Acids  R Group atoms contains Polar Covalent bonds  Hydrophilic properties Attracted to Water via Hydrogen Bonds  Amino Acids found on the Outside of the Protein Mutations can have a huge affect on the Structure  Degree of Polarity depends on: Polar Functional Groups Number of Carbon-Hydrogens Number of Aromatics SCHOOL OF BIOLOGICAL SCIENCES 17 AND APPLIED CHEMISTRY Polar Neutral Amino Acids Asparagine Serine Threonine SCHOOL OF BIOLOGICAL SCIENCES 18 AND APPLIED CHEMISTRY Polar Neutral Amino Acids Tyrosine Glutamine SCHOOL OF BIOLOGICAL SCIENCES 19 AND APPLIED CHEMISTRY Basic Amino Acids  R Group atoms contains a Nitrogen atom Accept a Proton at low pH (Acidic) Becomes Positively charged  Hydrophilic properties Attracted to Water via Hydrogen Bonds Found near the Surface of a Protein SCHOOL OF BIOLOGICAL SCIENCES 20 AND APPLIED CHEMISTRY Basic Amino Acids Lysine Arginine SCHOOL OF BIOLOGICAL SCIENCES 21 AND APPLIED CHEMISTRY Basic Amino Acids Histidine SCHOOL OF BIOLOGICAL SCIENCES 22 AND APPLIED CHEMISTRY Acidic Amino Acids  R Group atoms contains a Carboxyl group Donate a Proton at high pH (Basic) Becomes Negatively charged  Hydrophilic properties Attracted to Water via Hydrogen Bonds Found near the Surface of a Protein SCHOOL OF BIOLOGICAL SCIENCES 23 AND APPLIED CHEMISTRY Acidic Amino Acids Aspartic Acid Glutamic Acid SCHOOL OF BIOLOGICAL SCIENCES 24 AND APPLIED CHEMISTRY Amino Acids SCHOOL OF BIOLOGICAL SCIENCES 25 AND APPLIED CHEMISTRY Summary  Proteins are polymers of Amino Acids  Amino Acids have an Amine group Carboxyl group R-group Side Chain  R-group gives the Amino Acid it’s characteristics Polar vs Non-Polar Acidic vs Basic  Characteristics of the Amino Acids dictate the Structure of the Protein You don’t need to memorize the amino acids You should be able to identify the R-group characteristics SCHOOL OF BIOLOGICAL SCIENCES 26 AND APPLIED CHEMISTRY