A histidine side chain is known to have an important role in the catalytic mechanism of an enzyme; however, it is not clear whether histidine is required in its protonated(charged) or unprotonated (uncharged) state. To answer this question you measure enzyme activity over a range of pH, with the results shown in the figure below.1201008040208 9 10pH7Which form of histidine is required for enzyme activity?O The charged, protonated form of histidine is required for enzyme activity.The charged, deprotonated form of histidine is required for enzyme activity.The uncharged, protonated form of histidine is required for enzyme activity.O The uncharged, deprotonated form of histidine is required for enzyme activity.activity (% of maximum)

Histidine contains an amino group, a carboxylic acid group and imidazole ring as side chain.

Answered: A histidine side chain is known to have…

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

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Similar questions

The following molecules act as either inhibitors or activators of the enzyme that converts fructose-6-phosphate to fructose-1,6- diphosphate. Which do you think are activators? (A) ADP B AMP ATP citrate
Compare and contrast the biological roles of the following amino acids the following pairs ofamino acids. Once you have documented these role state which member of the pair is most important and why.
For the chemical reaction that results in the formation of a peptide bond between two amino acids, AG = +4 kcal/mol. Based on this information, which of the following labels would be appropriate to describe this reaction? O Exergonic O Hydrolysis O Redox O Endergonic
Draw a diagram of the aspartic acid side chain in the protonated and unprotonated states. Calculate the ratio of the protonated and unprotonated forms of this side chain that would exist at pH 7 (assume pKa = 4).
Some enzymes can be regulated by covalent modification, in which a group is covalently bonded to an amino acid side chain. Phosphorylation of side chains is a common regulatory covalent modification. In this essay, you will explore phosphorylation of side chains. Compare and contrast the types of interactions a free alcohol side chain such as serine could make with that of a phosphorylated alcohol such as phosphoserine (pSer). Could this modification affect the 3D structure of the protein? How? Imagine you are trying to separate a protein containing an unphosphorylated S residue from the same protein containing a pSer residue. Discuss how you could use ion-exchange chromatography to separate these two proteins
Can you explain the various options and how did you come to the answer? How to know whether histine is required in protonated or unprotected state? Does the level of the pH affect the result?
The pKa for histidine is pKa = 6.1 while that for cysteine is pKa = 8.0 2. Assume that both histidine and cysteine are catalytic groups for a particular enzyme. Assume also that the side chain of cysteine must be in the deprotonated form. Estimate the pH at which the catalytic activity of this enzyme is the maximum and sketch a pH-activity graph.
An enzyme contains an active site aspartic acid with a pKa = 5.0, whichacts as a general acid catalyst. On the accompanying template, draw thecurve of enzyme activity (reaction rate) versus pH for the enzyme (assumethat the protein is stably folded between pH 2–12 and that the active siteAsp is the only ionizable residue involved in catalysis). Briefly explain theshape of your curve.
New anti-cancer agents are being developed that target fatty acid synthase (FASN) due to a requirement for lipid synthesis to promote tumor cell replication. Describe why an enzyme inhibitor targeted to the following sites would or would not work to inhibit lipid synthesis. Explain your answer. If you’re not sure whether it will work, make an argument for and against it working. ACP site on FASN The dimer interface between monomers of FASN Targeting FASN to mitochondrial matrix

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