6. A quantitative amino acid analysis reveals that bovine serum albumin (BSA) contains0.58% tryptophan (MW=204) by weight. (a) Calculate the minimum molecular weight ofBSA (i.e., assume there is only one Trp residue per protein molecule). (b) Gel filtration ofBSA gives a molecular weight estimate of 70,000. How many Trp residues are present ina molecule of serum albumin?

Amino acids, such as glycine, tryptophan, and alanine are organic molecules that contain an amino…

Answered: 6. A quantitative amino acid analysis…

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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1. The human hemoglobin molecule, like all mammalian he- moglobins, is comprised of two a-chains and two ß-chains con- ₂ taining 141 and 146 amino acid residues, respectively. Be- cause the molecule possesses two-fold symmetry, there are a1-a2, B1-B2, and a1-B2 interfaces formed by amino acid sidechains through which structural changes are transmitted underlying ligand binding. The most important of these is the a1-B2 interface that is illustrated in the diagram on the right. All of the sidechain interactions across the a1-B2 interface are hydrophobic except for that between Asp(a94) and Asn- (B102). This is the only polar interaction across the α1-³2 in- terface and it helps to stabilize the oxy- or R-conformation. Its approximate location in the Hb molecule is represented by the red double arrow in the diagram on the right. His FG4 97 Asp G1 (99) Tyr C7 (42) Hb mutant (a) T State (deoxy) 95 The C6 41 (a) The diagram below on the right-hand side illustrates the polar Asp(a94). . . Asn…
A quantitative amino acid analysis reveals that bovine serum albumin (BSA) contains 0.58% tryptophan (Mr 204) by weight.(a) Calculate the minimum molecular weight of BSA (i.e., assume there is only one Trp residue per protein molecule).(b) Size-exclusion chromatography of BSA gives a molecular weight estimate of 70,000. How many Trp residues are present in a molecule of serum albumin?
16. A quantitative study of the interaction of a protein with its ligand yielded the following results: Ligand concentration 0.5 1 2 3 4 5 6 9. 12 (μM) v (moles of 0.14 0.31 0.48 0.61 0.68 0.72 0.77 0.79 0.81 ligand bound per mole of protein) Plot a graph of ligand concentration versus v. Determine KD, the dissociation constant for the interaction between the protein and its ligand, from the graph.
1. Lactoferrin is an iron-binding glycoprotein that forms the antibiotic fragment lactoferricin during digestion. The protein was isolated from 1.5 liters of ewe skim milk by successive ammonium sulfate precipitation until a final salt concentration of 70% was obtained. Determine the amount (in g) of powdered ammonium sulfate needed in bringing the solution from (a) 0% to 40% saturation and (b) 40% to 70% saturation assuming that the volume remains constant. Initial concentration of (NH4)2SO4, % saturation 0 10 20 30 40 50 60 70 80 90 10 55 Final concentration of (NH4)2SO4, % saturation 30 40 50 60 70 80 Grams of solid (NH4)2SO4 to be added to 1 L of solution 176 242 314 390 472 561 657 117 405 491 584 59 421 351 438 20 113 57 182 121 61 251 325 63 188 126 195 130 65 260 337 270 202 281 135 67 210 140 70 90 761 685 511 609 533 365 292 219 146 HUGH LATLE 100 73 457 381 305 228 152 76
6a. Using your 5 mg/mL stock solution, you wish to make 100µL of the correct concentration of protein to load. How do you make this working solution? (Yes- you would want this to be in 1x sample buffer, but that makes this question more complicated. So for this question just make the protein in water.) Volume of 10mg/ml Final Volume ! 1 100μL of protein 6b. This is a 1: A N Body* @ 2 W S dilution. #3 X E D $ 4 A C R F B I % 5 T V MacBook Pro U וכ H E U 8 N J ( 0
2. (6) Examine the two proteins labelled a) and b). Which of the two Ramachandran plots, c) or d) is more likely to be derived from which protein? Explain how you determined this. (a) (b) (c) (d) ✓ (degrees) ✓ (degrees) +-180 120 60 -60 -120 -180 -180 +180 120 60 -120 -180 -180 0 (degrees) 0 (degrees) +180 +180
2. Draw the structure of pentapeptide Trp-Asp-Cys-Lys-Gln that would predominate in aqueous solution at pH=5.5. (Relevant pKa values are 2.2, 3.8, 8.3, 9.6 and 10.5.)
3. Approximate molecular weight for an unknown protein from gel-filtration experiment is 130 kDa. Thirty six mg of this pure protein was treated with excess of fluorodinitrobenzene. After the reaction and complete acid hydrolysis the mixture was found to contain 356 µg of dinitrobenzene derivative of methionine (free acid) and no other amino acid-dinitrobenzene derivatives. Is this protein consisting of single polypeptide chain or multiple subunits? If it consists of multiple subunits, then how many? From these data, can you calculate the molecular weight of the protein more precisely?
The ESI-MS spectrum in positive ionization mode for lysozyme is obtained. a. What is the molecular weight of the protein to 5 significant figures based on the two highlighted ion species? b. What is the charge of the peaks at 1101.5 and 1789.2.
4. The table below describes a procedure in preparing standard solutions of a protein sample with different concentrations. (A) Determine the concentrations of each tube if the starting concentration of the protein is 500 mg ml (B) Determine the equation of the line if the concentration (x-axis) was plotted vs the absorbance (y-axis). (C) What is the concentration, in mg ml of the diluted unknown protein sample if the absorbance at 595 nm is 0.333? Tube Volume of protein, Volume of water, Final concentration, Absorbance mL mL mg ml [at 595 nm) 1 0.00 5.00 0.113 2 0.70 4.30 0.184 3 1.40 3.80 0.251 14 2.10 2.90 0.329 2.80 2.20 0.385 3.50 1.50 0.454 7 4.20 0.80 0.503 5.00 0.00 0.577
Purification of a protein of unknown structure has been achieved. The natural protein has a molecular weight of 240,000, according to size-exclusion chromatography. Using a concentration of 6 M guanidine hydrochloride in the chromatography, a single peak can be identified as the molecular weight (MW) 60,000 of a protein. B-mercaptoethanol (BME) and guanidine hydrochloride (GHC) are used in tandem to produce proteins with mass masses of 34,000 and 26,000, respectively. The structure of this protein can be inferred from these facts.
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).

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