Homework Help is Here – Start Your Trial Now!
Science
Biochemistry
Consider a protein in which a negatively charged glutamic acid side chain (pKa=4.2)(pKa=4.2) makes a salt bridge (ion-ion interaction) with a positively charged histidine side chain (pKa=6.5)(pKa=6.5).

Consider a protein in which a negatively charged glutamic acid side chain (pKa=4.2)(pKa=4.2) makes a salt bridge (ion-ion interaction) with a positively charged histidine side chain (pKa=6.5)(pKa=6.5).

Biochemistry
Biochemistry
9th Edition
ISBN:9781319114671
Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Chapter1: Biochemistry: An Evolving Science
Section: Chapter Questions
Problem 1P
See similar textbooks
icon
Related questions
Question

Consider a protein in which a negatively charged glutamic acid side chain (pKa=4.2)(pKa=4.2) makes a salt bridge (ion-ion interaction) with a positively charged histidine side chain (pKa=6.5)(pKa=6.5). Do only part B.

Part A Do you predict that this salt bridge will become stronger, become weaker, or be unaffected as pH increases from pH = 6.9 to pH = 7.9? The salt bridge will become stronger. The salt bridge will become weaker. The salt bridge will be unaffected. Submit Previous Answers Correct At pH = 6.9 the glutamic acid (Glu) side chain will carry a charge of ~ -1 (at 3 pH units above the pKa for Glu, the side chain will be almost fully ionized); whereas the histidine (His) side chain will carry a charge of < +0.5 (at pH = pKa the charge on His would be +0.5; since pH = 6.9 is above its pKa, it will carry less (+) charge as it becomes more deprotonated). As the pH increase to 7.9, the charge on Glu will remain ~ -1 and the charge on His will decrease; thus, this salt bridge is predicted to become weaker as pH is raised from 6.9 to 7.9. Part B Justify your answer with calculations of partial charges on these amino acid side chains at pH = 6.9. (Hint: Consider lessons from Coulomb's law, and the Henderson-Hasselbalch equation.) Express your answers using two significant figures separated by a comma. VE ΑΣΦ 0.0022,2.5 ?
Transcribed Image Text:Part A Do you predict that this salt bridge will become stronger, become weaker, or be unaffected as pH increases from pH = 6.9 to pH = 7.9? The salt bridge will become stronger. The salt bridge will become weaker. The salt bridge will be unaffected. Submit Previous Answers Correct At pH = 6.9 the glutamic acid (Glu) side chain will carry a charge of ~ -1 (at 3 pH units above the pKa for Glu, the side chain will be almost fully ionized); whereas the histidine (His) side chain will carry a charge of < +0.5 (at pH = pKa the charge on His would be +0.5; since pH = 6.9 is above its pKa, it will carry less (+) charge as it becomes more deprotonated). As the pH increase to 7.9, the charge on Glu will remain ~ -1 and the charge on His will decrease; thus, this salt bridge is predicted to become weaker as pH is raised from 6.9 to 7.9. Part B Justify your answer with calculations of partial charges on these amino acid side chains at pH = 6.9. (Hint: Consider lessons from Coulomb's law, and the Henderson-Hasselbalch equation.) Express your answers using two significant figures separated by a comma. VE ΑΣΦ 0.0022,2.5 ?
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 3 steps

SEE SOLUTIONCheck out a sample Q&A here
Blurred answer
Similar questions
  • SEE MORE QUESTIONS
Recommended textbooks for you
Biochemistry
Biochemistry
Biochemistry
ISBN:
9781319114671
Author:
Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Publisher:
W. H. Freeman
Lehninger Principles of Biochemistry
Lehninger Principles of Biochemistry
Biochemistry
ISBN:
9781464126116
Author:
David L. Nelson, Michael M. Cox
Publisher:
W. H. Freeman
Fundamentals of Biochemistry: Life at the Molecul…
Fundamentals of Biochemistry: Life at the Molecul…
Biochemistry
ISBN:
9781118918401
Author:
Donald Voet, Judith G. Voet, Charlotte W. Pratt
Publisher:
WILEY
Biochemistry
Biochemistry
Biochemistry
ISBN:
9781305961135
Author:
Mary K. Campbell, Shawn O. Farrell, Owen M. McDougal
Publisher:
Cengage Learning
Biochemistry
Biochemistry
Biochemistry
ISBN:
9781305577206
Author:
Reginald H. Garrett, Charles M. Grisham
Publisher:
Cengage Learning
Fundamentals of General, Organic, and Biological …
Fundamentals of General, Organic, and Biological …
Biochemistry
ISBN:
9780134015187
Author:
John E. McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson
Publisher:
PEARSON
SEE MORE TEXTBOOKS