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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Two isoforms of an enzyme were discovered; isoform-1 produces a hormone that causes muscle spasms and isoform-2 makes a different hormone (from the same substrate) that lowers cholesterol levels. a) What strategy would you employ as a medicinal chemist to develop a drug that prevents muscle spasms without raising cholesterol levels? The active sites of isoform-1 and -2 are the same except isoform-1 has a cysteine residue and isoform-2 has a phenylalanine residue at that same position. b) What two approaches would you take for designing a muscle spasm drug without a cholesterol level increase side effect?
Human blood serum contains a class of enzymes known as acid phosphatases, which hydrolyze biological phosphate esters under slightly acidic conditions (pH 5.0): R-O-P-O3-2 + H2O --> R-OH + HO-P-O3-2. Acid phosphatases are produced by erythrocytes, the liver, kidney, spleen, and prostate gland. The enzyme from the prostate gland is clinically important because an increased activity in the blood is frequently an indication of cancer of the prostate gland. The phosphatase from the prostate gland is strongly inhibited by tartrate ion, but acid phosphatases from other tissues are not. How can this information be used to develop a commercial specific procedure for measuring the activity of the acid phosphatase of the prostate gland in human blood serum? * 1. Prostate cancer cannot be diagnosed biochemically. 2. Use tartrate to inhibit phosphatase from prostate gland and then subtract the results from the total serum enzyme activities to get an…
A histidine side chain is known to play an import-ant role in the catalytic mechanism of an enzyme; how-ever, it is not clear whether histidine is required in its pro-tonated (charged) or unprotonated (uncharged) state. Toanswer this question you measure enzyme activity over arange of pH, with the results shown in Figure Q2–1. Whichform of histidine is required for enzyme activity?
The activity of an enzyme requires a glutamic acid to display its -COOHfunctional group in the protonated state. Suppose the pKa of the -COOHgroup is 4.07.(a) Will the enzyme be more active at pH 3.5 or 4.5? Explain.(b) What fraction of the enzymes will be active at pH = 4.07? Explain.(c) At what pH will the enzyme show 78% of maximal activity?
The breakdown of a complex carbohydrate into its monomeric unit can be described as an enzyme-catalyzed reaction that has a deltaG(∆G) of -90kcal/mol. Suppose you were to add triple the amount of enzyme into this reaction - what would be the ∆G of this reaction?
Why might the compound shown below act as a transition state analog of phosphoglucose isomerase? A drawing of the normal transition state for this enzyme is needed.
If only a few (two or three) amino acid residues are involved in enzyme function, state at tworeasons why it is necessary for the enzyme to be made up of so many amino acid residues?
When free water molecules are excluded from an enzyme’s catalytic pocket, is a catalytic −OH group on an amino acid side chain a stronger or weaker nucleophile? Explain.
What type of bonds in the tertiary structure of the enzyme break at high temperatures? Which ones will not break?
The dynorphins are a group of opioid peptides that play an important role in changes in the brain associated with cocaine addiction. One of these peptides, dynorphin A, contains the following amino acid sequence: Tyr–Gly–Gly–Phe–Leu–Arg–Arg–Ile–Arg–Pro–Lys–Leu–Lys. Draw the amino acids and peptide fragments formed when dynorphin A is treated with each reagent or enzyme: (a) chymotrypsin; (b) trypsin; (c) carboxypeptidase; (d) C6H5N=C=S.

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