Amino Acids PDF

1 AMINO ACIDS Structures and Properties Essential Amino Acids Molecular Handedness Peptide Bond Formation and Characteristics Biochemically Important Small Peptides  2 Amino acid the building blocks of protein molecul...

1 AMINO ACIDS Structures and Properties Essential Amino Acids Molecular Handedness Peptide Bond Formation and Characteristics Biochemically Important Small Peptides  2 Amino acid the building blocks of protein molecule contains both an amino group and a carboxylic acid functional group and a side chain all attached to an ɑ-carbon nature of this side chain distinguishes ɑ-amino acids from each other  5 Standard Amino Acid is one of the 20 amino acids normally found in proteins building blocks of protein There are four categories: nonpolar amino acids polar neutral amino acids polar acidic amino acids, and polar basic amino acids.  6 Nonpolar, Neutral Side Chains is an amino acid that contains one amino group, one carboxyl group, and a nonpolar side chain are hydrophobic  7 Nonpolar, Neutral Side Chains  8 Nonpolar, Neutral Side Chains  9 Nonpolar, Neutral Side Chains  10 Polar, Neutral Side Chains is an amino acid that contains one amino group, one carboxyl group and a side chain that is polar but neutral in physiological pH, the side chain of a polar neutral amino acid is neither acidic nor basic  11 Polar, Neutral Side Chains  12 Polar Acidic Amino Acid is an amino acid that contains one amino group and two carboxyl groups, the second carboxyl group being part of the side chain physiological pH, the side chain of a polar acidic amino acid bears a negative charge the side-chain carboxyl group  13 Polar Acidic Amino Acid  14 Polar Basic Amino Acid is an amino acid that contains two amino groups and one carboxyl group, the second amino group being part of the side chain at physiological pH, the side chain of a polar basic amino acid bears a positive charge, the nitrogen atom of the amino group has accepted a proton  15 Polar Basic Amino Acid  16 Number of State in Hydrophobic Classification of Carboxyl Physiological or Amino Acids Amino Group pH Hydrophilic Group nonpolar amino acids 1 1 --- Hydrophobic polar neutral amino acids 1 1 Neutral Hydrophilic polar acidic amino acids, 1 2 Acidic Hydrophilic polar basic amino acids. 2 1 Basic Hydrophilic  17 Names of the Standard Amino Acids often abbreviated using three-letter codes except in four cases, these abbreviations are the first three letters of the amino acid's name one-letter code for amino acid names  18 Names of the Standard Amino Acids  19 Three-Letter One-Letter Amino Acid Abbreviation Abbreviation Alanine Ala A Cysteine Cys C Valine Val V Serine Ser S Tryptophan Trp W  20 THE ESSENTIAL AMINO ACIDS  21 Essential Amino Acid is an amino acid needed by the human body that must be obtained from dietary source because it cannot be synthesized within the body 22 *  23 Phenylalanine Function/s: precursor for the neurotransmitters tyrosine, dopamine, epinephrine and norepinephrine Sources: milk, cheese, and yogurt  24 Valine Function/s: helps stimulate muscle growth and regeneration and is involved in energy production Sources: beef, chicken, pork, fish, tofu, yogurt, beans, podded peas, seeds, nuts, and whole grains like oatmeal  25 Threonine Function/s: part of structural proteins such as collagen and elastin, which are important components of the skin and connective tissue Sources: lean beef, soy, pork, chicken, liver, cheese, shellfish, nuts, seeds, and beans  26 Tryptophan Function/s: is precursor to serotonin, a neurotransmitter that regulates your appetite, sleep and mood Sources: chicken, eggs, cheese, fish, peanuts, pumpkin and sesame seeds.  27 Methionine Function/s: necessary for tissue growth and the absorption of zinc and selenium Sources: beef, fish, pork, tofu, milk, cheese, nuts, beans, and whole grains  28 Leucine Function/s: helps regulate blood sugar levels, stimulates wound healing and produces growth hormones Sources: chicken, beef, pork, fish (tuna), tofu, milk, cheese, squash seeds, and eggs  29 Isoleucine Function/s: immune function, hemoglobin production and energy regulation Sources: eggs, soy, seaweed, turkey, chicken, cheese, and fish  30 Lysine Function/s: protein synthesis, hormone and enzyme production and the absorption of calcium, production of collagen and elastin Meat, specifically red meat, pork, and poultry. Sources: cheese, sardines, eggs, tofu, isolated soy protein, and Spirulina.  31 Histidine Function/s: used to produce histamine, a neurotransmitter that is vital to immune response, digestion, sexual function and sleep-wake cycles Sources: meat, eggs, dairy protein (casein), cereal grains, and legumes  32 Arginine is an essential amino acid in children required for growth but not an essential amino acid for adults Sources: milk, cheese, and yogurt Functions: wound healing, removing ammonia from the body, immune function  33 Complete Dietary Protein contains all of the essential amino acids the same relative amount in which the body needs them animal sources is usually complete dietary protein such as casein from milk and proteins found in meat, fish, and eggs soy is the only common plant protein that is a complete dietary protein  34 Incomplete Dietary Protein is a protein that does not contain adequate amounts, relative to the body’s needs of one or more of the essential amino acids Gelatin from animal sources (tryptophan is the limiting amino acid)  35 Incomplete Dietary Protein limiting amino acids in plants lysine (wheat, rice, oats, and corn) methionine (beans and peas), and tryptophan (corn and beans).  36 Limiting Amino Acid is an essential amino acid that is missing or present but inadequate amounts, in an incomplete dietary protein  37 Complementary Dietary Proteins are two or more incomplete dietary proteins that when combined, provide an adequate amount of all essential amino acids Rice and Beans  38 CHIRALITY AND MOLECULAR HANDEDNESS  39 Alpha (ɑ-) amino acid An amino acid in which the amino group is bonded to the carbon atom next to the -COOH group. 40  41 Fischer Projection Formulas 1. The -COOH group is put at the top of the projection formula, the R group at the bottom. This positions the carbon chain vertically. 2. The -NH3, group is in a horizontal position. Positioning it on the left denotes the L isomer, and positioning it on the right denotes the D isomer. 42  43 BIOCHEMICALLY IMPORTANT SMALL PEPTIDES  44 Peptide bond is an amide bond that links two amino acids together.  45 Polypeptide is a long unbranched chain of amino acids.  46 Peptide bond The end with the free H3N+ group is called the N-terminal end and the end with the free COO- group is called the C-terminal end. The individual amino acids within a peptide chain are called amino acid residues.  47 Amino Acid Residues residue is the portion of an amino acid structure that remains, after the release of H2O, when an amino acid participates in peptide bond formation becomes part of a peptide chain.  48 Peptide Nomenclature Rule 1: The C-terminal amino acid residue (located at the far right of the structure) keeps its full amino acid name Rule 2: All of the other amino acid residues have names that end in -yl. The -yl suffix replaces the -ine or -ic acid ending of the amino acid name, except for tryptophan (tryptophyl), cysteine (cystenyl), glutamine (glutaminyl), and asparagine (asparaginyl) Rule 3: The amino acid naming sequence begins at the N-terminal amino acid residue  49 Peptide Nomenclature Glu-Ser-Ala Glutamyl-seryl-alanine Gly-Tyr-Val Glycyl-tyrosyl-valine  50 Isomeric Peptides contain the same amino acids but in different order are different molecules (constitutional isomers) with different properties.  51 Small Peptide Hormones produced by the pituitary gland, are oxytocin and vasopressin nonapeptide (nine amino acid residues) with six of the residues held in the form of a loop by a disulfide bond formed from the interaction of two cysteine residues.  52 Small Peptide Hormones Oxytocin regulates uterine contractions and lactation. Vasopressin regulates the excretion of water by the kidneys; it also affects blood pressure. Another name for vasopressin is antidiuretic hormone (ADH)  53 Small Peptide Neurotransmitters Enkephalins are pentapeptide neurotransmitters produced by the brain itself that bind at receptor sites in the brain to reduce pain  54 Small Peptide Neurotransmitters Met-enkephalin is involved in phenomena associated with modulated pain perception, regulation of memory and emotional conditions Leu-enkephalin controls gonadal function.  55 Small Peptide Antioxidant Glutathione is a tripeptide (Glu- Cys-Gly) that functions as antioxidant protecting cellular contents from oxidizing agents such as peroxides and superoxides  56 Small Peptide Antioxidant an acidic amino acid, is bonded to Cys through the side-chain carboxyl group rather than through its a-carbon carboxyl group