© 2000 Prentice Hall. All rights reserved.

Dr. Glaser's "Chemistry is in the News"
To Accompany Bruice, Organic Chemistry, 3/e.
Chapter 21. Amino Acids, Peptides, and Proteins.


For each of the following questions, please refer to the following article:
MIDWIFE FINDS DELIVERANCE IN HIS JOB
by Melissa Fletcher Stoeltje (Houston Chronicle, April 5, 1998)


Editorial Comments

Chemistry affects everybody's life.
From the moment you are on born. Literally.
Chemistry very likely affected your life on the day you were born.

Oxytocin is a hormone that induces labor in pregnant women. Pitocin, the drug that is commonly administered to enhance labor, is nothing but synthetic oxytocin.


Pertinent Text References
Chapter 20. Amino Acids, Peptides, and Proteins



Questions

Question 1: Oxytocin has the sequence Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2. Consider the part R-Leu-Gly-NH2 and write a detailed reaction mechanism for the peptide bond formation between R-Leu-NH2 and HOOC-Gly-NH2.

Answer 1: Bruice 3/e, Chapter 21.7.



Question 2: Oxytocin has the sequence Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2 and contains a Cys-S-S-Cys cross-link. Provide the names of all of the amino acids in this sequence and give the structural formula for this oligopeptide.

Answer 2: Cysteine - tyrosine - isoleucine - glutamine - asparagine - cysteine - proline - leucine - glycine - NH2. There is a -S-S- bridge between the two Cys units.



Question 3: Explain how cysteine can destroy harmful oxidising agents via the formation of disulfide cross-links. In your explanation, use glutathione as an example. Glutathioine is the tripeptide Glu-Cys-Gly.

Answer 3: Bruice 3/e, Chapter 21, p. 934ff.



Question 4: Describe how oxytocin could be synthesized via an automated Merrifield synthesis [and subsequent oxidation to form the disulfide cross-link].

Answer 4: Bruice 3/e, Chapter 21.10.



Chemistry & Society.
The pitosin website at Childbirth.org provides much detail about the induction of labor. Read the section on "Active Management of Labor". This section emphasizes that a good process for active management of labor is much more than merely the injection of pitosin. Discuss the differences between the Dublin AML model and the American AML process.