Concept explainers
Interpretation:
The structure of the most abundant form of cysteine at the given pH values is to be drawn.
Concept introduction:
The general form of an
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Organic Chemistry: Principles and Mechanisms (Second Edition)
- The side chain of cysteine is weakly acidic. Suppose in a protein, the side chain of a cysteine residue is surrounded by the side chains of several isoleucine residues. Would this make the side chain of the cysteine residue more acidic or less acidic? Please explain your answer.arrow_forwardDraw all of the structures of cysteine as the pH increases from low to high, then sketch a titration curve that best represents the titration of cysteine. in the curve, label each: x-axis, y-axis, pKa (COOH), pKa (NH3+), pKa(R-group), and the calculated pI value.arrow_forwardConsider the ring structure of b-d-glucose. It will give a positive test reducing sugars. Describe how can that happen in a PH =7 solution such as feelingsarrow_forward
- Which of the common amino acids is not chiral? Sketch its structure and explain why it does not manifest chirality.arrow_forwardplease explain What percentage of a side-chain sulfhydryl group of cysteine is protonated at pH 7.9?arrow_forward(b) Describe how the charge of some amino groups in a protein might differ at pH 9.0 and pH 5.0. the charge on the amino group will differ at pH 5 and pH 9 which will depend on the pKa of the amino acid. (c) Describe how the charge of some carboxyl groups in a protein might differ at pH 9.0 and pH 5.0. charge on carboxyl group will differ at pH 5 and pH 9 which will depend on the pKa of the amino acid. (d) Given your answers to parts (b) and (c), what kind of intramolecular interactions in beta-galactosidase are most likely to be affected by a change in pH from 9.0 to 5.0? (e) Could the interactions you mention in part (d) affect the catalytic activity of beta-galactosidase?arrow_forward
- 1a) Biotin has a single ionizable group with a pKa of 4.5. If you dissolved biotin in an aqueous solution at pH 7.0, would this ionizable group be protonated or deprotonated? Briefly explain why the molecule would be in that form at pH 7.0.arrow_forward(2) Caffeine (C8H10N4O2) is a weak base with a pKь of 10.4. Calculate the pH of a solution containing a caffeine concentration of 455 mg/L.arrow_forwardDraw the structure of alanine in a solution at pH = 0arrow_forward
- Given that C6H11COOH has a pKa = 4.8 and C6H11N + H3 has a pKa = 10.7, what pH would you make the water layer to cause both compounds to dissolve in it?arrow_forwardTyrosine is a triprotic weak acid, with pKa1=2.41, pKa2=8.67, and pKa3=11.01. a) calculate the final [OH-] of a solution that starts with .3OM of the fully basic form. Do not assume the concentration of base is constant. b) at what pH range(s) would tyrosine act best as a buffer? c) calculate the pH of a solution at equilibrium which started with 0.043M at the monoprotonated H2A- form *Please show all work and not just answers, I'm looking to understand how to solve problems like these! TIAarrow_forwardWrite the Henderson-Hasselbalch equation for a solution of methylamine. Calculate the quotient [CH3NH2]/[CH3NH13] at (a) pH 4.00; (b) pH 10.632; (c) pH 12.00.arrow_forward
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