3. Sequence Determination of the Brain Peptide Leucine Enkephalin A group of peptides that influence nerve transmission in certain parts of the brain has been isolated from normal brain tissue. These peptides are known as opioids because they bind to specific recepton that also bind opiate drugs, such as morphine and naloxone. Opioids thus mimic some of the properties of opiates. Some researchers consider these peptides to be the brain's own painkiller Using the information below, determine the amino acid sequence of the opioid leucine enkephalin. Explain how your structure is consistent with each piece of information. (a) Complete hydrolysis by 6 M HCI at 110 _C followed by amino acid analysis indicated the presence of Gly, Leu, Phe, and Tyr in a 2:1:1:1 molar ratio. (b) Treatment of the peptide with 1-fluoro-2,4-dinitrobenzene, which reacts with free amines, followed by complete hydrolysis and chromatography indicated the presence of the 2,4- dinitrophenyl derivative of tyrosine. No free tyrosine could be found. (c) Complete digestion of the peptide with chymotrypsin followed by chromatography yielded fre tyrosine and leucine, plus a tripeptide containing Phe and Gly in a 1:2 ratio.
3. Sequence Determination of the Brain Peptide Leucine Enkephalin A group of peptides that influence nerve transmission in certain parts of the brain has been isolated from normal brain tissue. These peptides are known as opioids because they bind to specific recepton that also bind opiate drugs, such as morphine and naloxone. Opioids thus mimic some of the properties of opiates. Some researchers consider these peptides to be the brain's own painkiller Using the information below, determine the amino acid sequence of the opioid leucine enkephalin. Explain how your structure is consistent with each piece of information. (a) Complete hydrolysis by 6 M HCI at 110 _C followed by amino acid analysis indicated the presence of Gly, Leu, Phe, and Tyr in a 2:1:1:1 molar ratio. (b) Treatment of the peptide with 1-fluoro-2,4-dinitrobenzene, which reacts with free amines, followed by complete hydrolysis and chromatography indicated the presence of the 2,4- dinitrophenyl derivative of tyrosine. No free tyrosine could be found. (c) Complete digestion of the peptide with chymotrypsin followed by chromatography yielded fre tyrosine and leucine, plus a tripeptide containing Phe and Gly in a 1:2 ratio.
Human Anatomy & Physiology (11th Edition)
11th Edition
ISBN:9780134580999
Author:Elaine N. Marieb, Katja N. Hoehn
Publisher:Elaine N. Marieb, Katja N. Hoehn
Chapter1: The Human Body: An Orientation
Section: Chapter Questions
Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...
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***not graded, just a practice problem I do not understand. Thank you so much!
Transcribed Image Text:3.
Sequence Determination of the Brain Peptide Leucine Enkephalin A group of
peptides that influence nerve transmission in certain parts of the brain has been isolated from
normal brain tissue. These peptides are known as opioids because they bind to specific receptors
that also bind opiate drugs, such as morphine and naloxone. Opioids thus mimic some of the
properties of opiates. Some researchers consider these peptides to be the brain's own painkillers.
Using the information below, determine the amino acid sequence of the opioid leucine
enkephalin. Explain how your structure is consistent with each piece of information.
(a) Complete hydrolysis by 6 M HCI at 110 _C followed by amino acid analysis indicated the
presence of Gly, Leu, Phe, and Tyr in a 2:1:1:1 molar ratio.
(b) Treatment of the peptide with 1-fluoro-2,4-dinitrobenzene, which reacts with free amines,
followed by complete hydrolysis and chromatography indicated the presence of the 2,4-
dinitrophenyl derivative of tyrosine. No free tyrosine could be found.
(c) Complete digestion of the peptide with chymotrypsin followed by chromatography yielded free
tyrosine and leucine, plus a tripeptide containing Phe and Gly in a 1:2 ratio.
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