2. (10 points) The structure for the amino acid histidine is shown below (at pH 1)....
(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...
explain the following answers 8. (3 pts) Consider the structure of histidine, shown below, along with the three pk, values of the three acidic groups. What is the isoelectric point (pl) for histidine? NH2 pka COOH = 1.77 = 6.10 pka, NH3+ = 9.18 pka, ning A) 3.94 C) 5.68 B) 5.48 D) 7.64 histidine OH 9. (3 pts) Which one of the following forms of histidine is the form that would mainly exist near pH = 4? HN NH2...
Question 17 (4 points) What is the correct structure of histidine at pH 1? The pKa values are 1.8 (carboxylic acid). 9.2 (amine (conjugate acid)), and 6.0 (sidechain, the double bonded N in ring)? OH NH H2 СНС NH С NH H2 CHC 뿔 NH OH H2 NH CH-C NH2 ON 0 NH 42 CH-C NH3
An amino acid with a pl of 5.9 is placed in a solution with a pH = 7. This amino acid will be An amino acid with three ionizable groups is placed in a solution with a pH of 8. The three groups are -CO2H, --NH3+, and -OH. The pka's of these group are 2.90,8.79, and 15.4. In the solution with a pH = 7 the groups will have the following protonation states: positively charged negatively charged neutral CO2H CO2-...
1. a. For the following groups, indicate their predominant ionic species (draw the chemical structure) at pH 7.4: a. The side chain amino group (–NH3+) of the amino acid lysine, pKa=10.5. The side chain carboxyl group (-COOH) of the amino acid glutamate, pKa=4.1. b.For a buffer with a pKa of 8.03 : How will the pH and buffering capacity change when HCl is added to the buffer in “a”? How will the pH and buffering capacity change when NaOH is...
Calculate the pH at the isoelectric point for a 0.10 M solution of the amino acid phenylanaline. Ka(-CO2H) = 6.30 x 10^-3 and Ka(-NH3) = 4.0 x 10^-10 for phenylalanine.
A colleague presents you the structure of a hexapeptide (sequence: KLVFFA) at neutral pH. With your knowledge of amino acid pKa values, what is the isoelectric point of this peptide? HN NH HN HN NH NH
What is the correct structure of histidine at pH 1? The pKa values are 1.8 (carboxylic acid), 9.2 (amine (conjugate acid)), and 6.0 (sidechain, the double bonded N in ring)? 0C NH H2 CH C NH, NH H2 CH-C NHS OH O=C NH A
1. Calculate pl value of His. COO H-C-CH NH3 Histidine (His, H) 2. The R group of lysine has an amino group that can be positively charged or lose a proton to become neutral. The pKa of the amino group is 10.8. Determine the fraction of amino group that is protonated at pH 9.8 and at pH 11.8. 1. Calculate pl value of His. COO H-C-CH NH3 Histidine (His, H) 2. The R group of lysine has an amino group...
At a pH of 4: Amino acid 1 OH Amino acid 2 NH OH HN NH, OH pka Amino Amino Acid 1 Acid 2 9.82 9.18 Amino terminus Carboxy terminus 2.1 1.77 Side chain 3.86 6.1 O (Answer B) the R group (side chain) on amino acid 1 will be deprotonated A and B (Answer A) the amino terminus on amino acid OH HN OH pka Amino Acid 1 Amino Acid 2 Amino terminus 9.82 9.18 Carboxy terminus 2.1 1.77...