Oxytocin, a nonapeptide hormone secreted by the pituitary gland, functions by stimulating uterine contraction and lactation during childbirth. Its sequence was determined by the following evidence: 1. Oxytocin is a cyclic compound containing a disulfide bridge between two cysteine residues. 2. When the disulfide bridge is reduced, oxytocin has the constitution Asn, Cys2, Gln, Gly, lle, Leu, Pro, Tyr. 3. Partial hydrolysis of oxytocin yields seven fragments: Asp-Cys, Ile-Glu, Cys-Tyr, Leu-Gly, Tyr-lle-Glu, Glu-Asp-Cys, Cys-Pro-Leu. 4. Gly is the C-terminal group. 5. Both Glu and Asp are present as their side chain amides (Gln and Asn) rather than as free side-chain acids. From the above information, determine the primary sequence of oxytocin and then draw the structure of the Leu-Gly fragment. • You do not have to consider stereochemistry. • You do not have to explicitly draw H atoms. • Do not include lone pairs in your answer. They will not be considered in the grading. • Draw the amino acid in zwitterion form. Θ H₂N OH N H H3C. CH3 ChemDoodle An error has been detected in your answer. Check for typos, miscalculations etc. before submitting your answer. 20

Oxytocin, a nonapeptide hormone secreted by the pituitary gland, functions by stimulating uterine contraction and lactation during childbirth. Its sequence was determined by the following evidence: 1. Oxytocin is a cyclic compound containing a disulfide bridge between two cysteine residues. 2. When the disulfide bridge is reduced, oxytocin has the constitution Asn, Cys2, Gln, Gly, lle, Leu, Pro, Tyr. 3. Partial hydrolysis of oxytocin yields seven fragments: Asp-Cys, Ile-Glu, Cys-Tyr, Leu-Gly, Tyr-lle-Glu, Glu-Asp-Cys, Cys-Pro-Leu. 4. Gly is the C-terminal group. 5. Both Glu and Asp are present as their side chain amides (Gln and Asn) rather than as free side-chain acids. From the above information, determine the primary sequence of oxytocin and then draw the structure of the Leu-Gly fragment. • You do not have to consider stereochemistry. • You do not have to explicitly draw H atoms. • Do not include lone pairs in your answer. They will not be considered in the grading. • Draw the amino acid in zwitterion form. Θ H₂N OH N H H3C. CH3 ChemDoodle An error has been detected in your answer. Check for typos, miscalculations etc. before submitting your answer. 20

Organic Chemistry

9th Edition

ISBN:9781305080485

Author:John E. McMurry

Publisher:John E. McMurry

Chapter26: Biomolecules: Amino Acids, Peptides, And Proteins

Section26.SE: Something Extra

Problem 57AP: Oxytocin, a nonapeptide hormone secreted by the pituitary gland, functions by stimulating uterine...

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Oxytocin, a nonapeptide hormone secreted by the pituitary gland, functions by stimulating uterine contraction and lactation during childbirth. Its sequence was determined by the following evidence:1. Oxytocin is a cyclic compound containing a disulfide bridge between two cysteine residues.2. When the disulfide bridge is reduced, oxytocin has the constitution Asn, Cys2, Gln, Gly, Ile, Leu, Pro, Tyr.3. Partial hydrolysis of oxytocin yields seven fragments: Asp-Cys, Ile-Glu, Cys-Tyr, Leu-Gly, Tyr-Ile-Glu, Glu-Asp-Cys, Cys-Pro-Leu.4. Gly is the C-terminal group.5. Both Glu and Asp are present as their side chain amides (Gln and Asn) rather than as free side-chain acids. From the above information, determine the primary sequence of oxytocin and then draw the structure of the Leu-Gly fragment.
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