BCHM 3050 Lecture 6 Outline of Last Lecture I Isoelectric Point pI a Nature of an Amino Acid b Nonpolar Amino Acids c Acidic Amino Acids d Basic Amino Acids Outline of Current Lecture I Significance of the Asymmetric Carbon II Essential vs Non Essential Amino Acids III Peptide Bond Formation IV Oxidation Reactions V Schiff s base VI Non standard Amino Acids Current Lecture I Significance of the Asymmetric Carbon a Stereoisomers molecules that have the same structural formulas and bonding patterns but with a different arrangements of atoms or groups in space b Enantiomers stereoisomers that are mirror images of each other i Two types dextrorotary and levorotary ii Only have the L form in nature can synthetically make the D form in the lab II Essential vs Non Essential Amino Acids These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute a Essential necessary in our diet but our body doesn t make them so we must ingest them b Non essential synthesized by the body as break down products c Brazil nut protein contains 18 methionine a few cysteine i Great source of sulfur containing amino acid cysteine and methionine III Peptide Bond Formation a Peptide bonds when bond two amino acids b Formed by losing a molecule of water c Reaction between carboxyl group of first amino acid and amino group of second amino acid d Bond is between the carbon and nitrogen atoms e Stronger than a single bond but not as strong as a double bond f Critical process in the formation of a protein g Once its formed it is not easy to reverse it h 1st amino acid N terminus which means that the amino group of this amino acid does not participate in any bonds free amino group i 2nd amino acid C terminus which mean that the carboxyl group of this amino acid does not participate in any bonds free carboxyl group j R groups do not participate in peptide bonding k Biologically important peptides not fully considered a protein Glutathione Vasopressin Oxytocin l IV Glutathione is a bi product not officially a protein Oxidation Reactions a Cysteine oxidation leads to a reversible disulfide bond b R group of Cysteine is CH2SH c Disulfide bridges stabilize proteins peptides absolutely essential d Need to Cysteine amino acids to form this bond V Schiff s base a Aldehyde group CHO and amino group reaction b Also known as Maillard reaction VI Non standard Amino Acids a There are about 300 non standard amino acids i Most are non protein amino acids ii Many are modifications of the standard amino acids iii A few are found in proteins iv All have special biological functions b GABA is derived from glutamic acid via glutamate decarboxylase removes alpha carboxyl c Serotonin vs Aggression high levels correlated with aggressive behavior low levels correlated with depression i Lots of the neurotransmitters are Non standard amino acids ii They are modifications of amino acids iii Do not need to memorize the structure just the functions d Hormones melatonin thyroxine indole 3 acetic acid i Changing the amount of sunlight received messes with the amount of melatonin created
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