BCHM 3050 Lecture 6 Outline of Last Lecture I. Isoelectric Point = pIa. Nature of an Amino Acidb. Nonpolar Amino Acidsc. Acidic Amino Acidsd. Basic Amino AcidsOutline of Current Lecture I. Significance of the Asymmetric CarbonII. Essential vs. Non-Essential Amino AcidsIII. Peptide Bond FormationIV. Oxidation Reactions V. Schiff’s baseVI. Non-standard Amino AcidsCurrent LectureI. Significance of the Asymmetric Carbona. Stereoisomers – molecules that have the same structural formulas and bonding patterns, but with a different arrangements of atoms or groups in spaceb. Enantiomers – stereoisomers that are “mirror images” of each otheri. Two types: dextrorotary and levorotaryii. Only have the L form in nature, can synthetically make the D form in the labII. Essential vs. Non-Essential Amino AcidsThese 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 themb. 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 Formationa. Peptide bonds = when bond two amino acidsb. Formed by losing a molecule of waterc. Reaction between carboxyl group of first amino acid and amino group of second amino acidd. Bond is between the carbon and nitrogen atomse. Stronger than a single bond but not as strong as a double bondf. Critical process in the formation of a proteing. Once its formed, it is not easy to reverse ith. 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 bondingk. Biologically important peptides, not fully considered a protein (Glutathione, Vasopressin, Oxytocin)l. Glutathione is a bi-product, not officially a proteinIV. Oxidation Reactions a. Cysteine oxidation leads to a reversible disulfide bondb. R group of Cysteine is CH2SHc. Disulfide bridges stabilize proteins/peptides (absolutely essential)d. Need to Cysteine amino acids to form this bondV. Schiff’s basea. Aldehyde group (CHO) and amino group reactionb. Also known as Maillard reactionVI. Non-standard Amino Acidsa. There are about 300 “non-standard” amino acidsi. Most are non-protein amino acidsii. Many are modifications of the standard amino acidsiii. A few are found in proteins iv. All have “special” biological functionsb. 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 acidsiii. Do not need to memorize the structure, just the functionsd. Hormones: melatonin, thyroxine, indole-3-acetic acidi. Changing the amount of sunlight received, messes with the amount of melatonin
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