4) 4. Which of the following mutationswould most likely keep the transitions of Tstate to R state in hemoglobin unchanged,or similar to the transitions that occur inthe native molecule? The three-lettercodes for amino acids are used, and thenumbers following the amino acidsdesignate the amino acid position in theprotein. By convention, the original, nativeamino acid is listed first, followed by themutational change.(a) Tyr 42 to Phe 42O (b) Tyr 42 to Gly 42(c) Asp 94 to Glu 94(d) Asp 94 to lle 94

Amino acids are biomolecules that have a carboxyl group, an amino group and a side group linked to…

Answered: 4. Which of the following mutations…

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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Which of the following mutations would most likely keep the transitions of T state to R state in hemoglobin unchanged, or similar to the transitions that occur in the native molecule? The three-letter codes for amino acids are used, and the numbers following the amino acids designate the amino acid position in the protein. By convention, the original, native amino acid is listed fırst, followed by the mutational change. Choose one: O A. Asp94→Ile94 O B. Tyr42→Phe42 O C. Asp94 Glu94 O D. Tyr42-Gly42
Certain individuals with mild forms ofβ-thalassemia produce, in addition to normal adulthemoglobin with two α chains and two β chains,lower levels of an unusual, so-called Leporehemoglobin with two α chains and two chains ineach of which the N-terminal half comes from anormal δ chain and the C-terminal half comesfrom a normal β chain. Certain other individualswho are asymptomatic produce a different, unusualanti-Lepore hemoglobin that contains two α chainsand two chains in which the N-terminal half comesfrom a normal β chain and the C-terminal halfcomes from a normal δ chain.a. Describe an event that could give rise to bothLepore and anti-Lepore hemoglobins.b. Are the mildly thalassemic individuals with Leporehemoglobin homozygotes or heterozygotes for theunusual allele?c. Why might these mildly thalassemic people produce less Lepore hemoglobin than normal adulthemoglobin?
Certain individuals with mild forms ofβ-thalassemia produce, in addition to normal adulthemoglobin with two α chains and two β chains,lower levels of an unusual, so-called Leporehemoglobin with two α chains and two chains ineach of which the N-terminal half comes from anormal δ chain and the C-terminal half comesfrom a normal β chain. Certain other individualswho are asymptomatic produce a different, unusualanti-Lepore hemoglobin that contains two α chainsand two chains in which the N-terminal half comesfrom a normal β chain and the C-terminal halfcomes from a normal δ chain.a. Describe an event that could give rise to bothLepore and anti-Lepore hemoglobins
1. How many different tripeptides are possible? How many carboxyl terminals of polypeptide chains are present in a molecule of hemoglobin? 2. You have isolated a pentapeptide composed of four glycine residues and one lysine residue that resides at the C-terminus of the peptide. Using the information provided in the legend of Figure 2.27, if the pK of the side chain of lysine is 10 and the pK of the terminal carboxyl group is 4, what is the structure of the peptide at pH 7? At pH 12? 3. The side chains of glutamic acid (pK 4.3) and arginine (pK 12.5) can form an ionic bond under certain conditions. Draw the relevant portions of the side chains and indicate whether or not an ionic bond could form at the following: (a) pH 4; (b) pH 7; (c) pH 12; (d) pH 13.
I. A protein, X, was Isolated from a pathogenlc mlcroorganism. The proteln Is a vlrulence factor whose path0genlclty lies In a heptapeptide of unknown sequence. After trypsin cleavage of the heptapeptide from protein X, the peptlde's compOsition and sequence was determined. The fOllowing were the results of the sequenclng process: 1. When the peptide was treated with dinitrofluorobenzene (DNFB), DNP-asp and a mixture of amino acids were produced. 2. When the same Intact peptide was treated with streptococcal protease, a pentapeptide of composition asp, asN, cys, gly and ser and 2 amlno acids were released. 3. When the heptapeptlde was also treated with hydrOxylamine HCI, a tripeptide and a tetrapeptide were obtained. The C-terminal amino acid of the tripeptide was asN. 1) What is the sequence of the heptapeptide if it is composed of cys, asp, lys, asN, gly and ser only? 2) What is the pl of the heptapeptide?
One of the amino acid sequences in the lysozyme protein from the bacterial virus T4 studiesby Streisinger and co-worker was .... Lys – ser – pro – ser – leu – asn – ala – ala – lys. Thisparticular amino acid was found to have changed to lys – val – his –his –leu –met –ala –ala–lys... as a result of a single nucleotide deletion and addition approximately 15 bases apartin the mRNA. Which base was deleted and which was added? Give the altered sequence of bases inthe altered amino acid.
One of the amino acid sequences in the lysozyme protein from the bacterial virus T4 studiesby Streisinger and co-worker was .... Lys – ser – pro – ser – leu – asn – ala – ala – lys. Thisparticular amino acid was found to have changed to lys – val – his –his –leu –met –ala –ala–lys... as a result of a single nucleotide deletion and addition approximately 15 bases apartin the mRNA.a. What is the sequence of the nucleotides that produce the original protein.b. Which base was deleted and which was added? Give the altered sequence of bases inthe altered amino acid.
9. The T conformation of the hemoglobin tetramer is stabilized (in part) by a salt linkage between the side chain of the lysine residue at position 40 in the a-chain of one aß dimer and the C-terminal carboxylate group of the ß-chain of the opposing aß dimer. Draw a diagram of this salt linkage (show complete side chains).
1. Sickle cell anemia results from a substitution of a valine for a glutamic acid. What do you expect the effect might be if the mutation were to have placed a leucine at that site? An aspartic acid? 2. Of the following amino acids, glycine, isoleucine, and lysine, which would you expect to be the most soluble in an acidic aqueous solution? Which the least? 3. How many structural isomers could be formed from a molecule with the formula C5H12? C4H8?
2. The diagram to the right shows the change in the structure of the C-terminal portion of each of the ẞ-subu- nits of human hemoglobin (HbA) in the oxyHb to deox- yHb or R-to-T transition. The hydrogen bonding interac- tion of the C-terminal ẞHis 146 residue with the side chain of Asp94, highlighted by the red ellipse, has been shown to be responsible for a major portion of the proton uptake associated with the Bohr effect. Treatment of HbA with the enzyme carboxypeptidase A (CPA) results in loss of the C-terminal ẞHis 146 and ẞTyr145 residues of the ẞ- subunits. (a) ( ) Draw a Hill plot [log(Y/[1-Y]) vs. log(pO2), Y = fraction of heme groups occupied by O2] to compare the values of the Hill coefficient nн and the O2-binding affinity at pH 7.4 of normal HbA before and after treat- ment of with CPA. (b) (' ) How will the plot for CPA-digested HbA change at pH 7.2? (c) 1 Hi5146 HN- ✓ Low PK B-chain. CH2 CH-NH-CO-CH-NH- CH₂ Tyr145 он HbO2 or R state Туг145 CH-CH2- OH co NH CH CH₂ His…
1. A pentapeptide has the sequence of H2N-Glu-His-Leu-Arg-Gly-COOH. a) What is the net charge of the peptide at pH 3, 8, and 11? (Use pka values for side chains and terminal amino and carboxyl groups in the table provided.) peptide. b) Estimate the pl for this pK, values Abbreviation/ symbol pk, M, (-COOH) (-NH5) (R group) pK; pKR Hydropathy Occurrence in index* proteins (%)* Amino acid pl Nonpolar, aliphatic R groups Glycine Alanine Proline Valine 2.34 -0.4 Gly G Ala A Pro P 75 9.60 5.97 7.2 89 115 2.34 9.69 10.96 6.01 6.48 5.97 1.8 1.6 4.2 3.8 4.5 7.8 5.2 1.99 117 131 Val V 2.32 2.36 9.62 9.60 6.6 9.1 Leucine Leu L 5.98 Isoleucine lle I 131 2.36 2.28 9.68 6.02 5.3 Methionine Met M 149 9.21 5.74 1.9 2.3 Aromatic R groups Phenylalanine Tyrosine Tryptophan 2.8 -1.3 3.9 3.2 Phe F 165 1.83 9.13 9.11 9.39 5.48 2.20 Tyr Y Trp W 181 10.07 5.66 204 2.38 5.89 -0.9 1.4 Polar, uncharged R groups Serine Ser S 105 2.21 6.8 9.15 9.62 5.68 5.87 5.07 5.41 5.65 -0.8 Threonine Thr T 119 2.11 -0.7 5.9…
10. (a) Provide the scheme of Merrifield peptide synthesis with suitable example. (b) Describe the mechanism of action of the enzyme lysozyme.

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