The pKa of the cysteine side chain group is 8.32, so it is about 88.5% dissociated...
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The pKa of the cysteine
side chain group is 8.32, so it is about 88.5% dissociated...
The activity of an enzyme requires a cysteine to display its -SH side chain in the...
The activity of an enzyme requires a cysteine to display its -SH side chain in the deprotonated state. The pKa of the -SH group is 8.3. At what pH will the enzyme show 65.0% of maximal activity?
Consider a protein with the acidic side chains, Amino Acid side-chain Arginine pKa = 12.48 Aspartic...
Consider a protein with the acidic side chains, Amino Acid side-chain Arginine pKa = 12.48 Aspartic Acid PKa = 3.90 Cysteine pKa = 8.33 Glutamic acid pKa = 4.07 Histidine pKa = 6.04 Lysine pKa =10.79 Tyrosine pKa =10.13 Given that the pH of blood is about 7.3, how many of the above side chains would be mostly in their ionic form (A-) in blood? 2 3 4 5
1. Calculate the charge on the side chain of the amino acid histidine using the Henderson-Hasselbach...
1. Calculate the charge on the side chain of the amino acid histidine using the Henderson-Hasselbach equation pH = pKa + log (A/HA+). Use pH =7 and a pKa = 6 and solve to 2 significant figures. 2. Cysteine proteases have unusually reactive cysteine side chains. For one of these enzymes in solution at pH 7 you are able to measure the amount of the deprotonated sulfhydryl (ie, the negatively charged species) as 40% of the total. Calculate the pKa...
If you have 4 Lysines, the side chain of Lysine has a Pka value of around...
If you have 4 Lysines, the side chain of Lysine has a Pka value of around 11, you are at pH of 4, are you going to take a proton off or to add? What is the net charge of these four Lys? What kind of ion exchange chormatography would you use?
Think about histidine. What percentage of His side chains will be charged at physiological pH? The...
Think about histidine. What percentage of His side chains will be charged at physiological pH? The pKa of the histidine R group is 6.0; physiological pH is 7.4 Use the Henderson-Hasselbalch equation to help you answer this.
Suppose that the organic acid shown below has 3 acidic groups with pKa = 2, 4...
Suppose that the organic acid shown below has 3 acidic groups with pKa = 2, 4 and 10. If a solution containing this acid were adjusted to pH 10, what would the average net charge on each molecule be? Round your answer to 3 significant figures, and include the sign (no sign if the net charge is 0 or positive, use the
What about the pKa values of the R groups of the seven amino acids containing an...
What about the pKa values of the R groups of the seven amino acids containing an ionizable R group? Tyr 10.5 Lys 10.5 Arg 12.5 Asp 3.9 Glu 4.1 His 6.0 Cys 8.4 Indicate the approximate net charge of each of these seven R groups at pH 7.4. Indicate the approximate net charge of each of these seven amino acids at pH 7.4. Note: remember the carboxyl and the alpha-amino group in addition to the ionizable (acidic or basic) R...
(1) The following diagram represents a titration curve of histidine as pH increases; pKa = 1.82 represents the terminal carboxylic acid group. pK, represents the terminal amino group: 6.0 r...
(1) The following diagram represents a titration curve of histidine as pH increases; pKa = 1.82 represents the terminal carboxylic acid group. pK, represents the terminal amino group: 6.0 represents the R-group, and pK, E 9.17 7.59 pH 182 3.0 20 10 H (equivalents) At what point on the diagram is histidine predominantly present as the following species? COO A, at pH < 1.82 B. between pH 1.82 and pH 6.0 C) between pH 6.0 and pH 9.17 D. at...
A base, with a pKa of 9.5 on a primary amino group, can diffuse across biological...
A base, with a pKa of 9.5 on a primary amino group, can diffuse across biological membranes when it carries no net charge. What percentage of the base would be in such a form at close to physiological pH, 7.5? Explain your answer and how you got it. A. 100% B. 90% C. 50% D. 10% E. 1%
The pK of the side chain of amino acid X in a polypeptide is normally in...
The pK of the side chain of amino acid X in a polypeptide is normally in the range of 9-10 and carries a positive charge when protonated. Suppose you have a soluble globular protein and you find there is an X that has a pK of 6.5. What is the most likely reason for such a large drop in pK? Circle the correct answer. a) X is on the surface of the protein where it ion pairs with the carboxylate...
(1) The following diagram represents a titration curve of histidine as pH increases; pKa = 1.82 represents the terminal carboxylic acid group. pK, represents the terminal amino group: 6.0 represents the R-group, and pK, E 9.17 7.59 pH 182 3.0 20 10 H (equivalents) At what point on the diagram is histidine predominantly present as the following species? COO A, at pH < 1.82 B. between pH 1.82 and pH 6.0 C) between pH 6.0 and pH 9.17 D. at...
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