The activity of a pore-forming membrane protein, PorinA1, was tested in different lipid bilayers at 60 °C. Each bilayer is composed of a single type of phosphoglyceride. The four different phosphoglycerides usedare shown in the table below together with the corresponding average hydrophobic thickness of the bilayer formed:PhosphoglycerideBilayer hydrophobic thickness ( A)Dilauroylphosphatidylcholine (DLPC)30.7Dimyristoylphosphatidylcholine (DMPC)34.2Dipalmitoylphosphatidylcholine (DPPC)38.1Distearoylphosphatidylcholine (DSPC)42.2PorinA1 is found to have the greatest activity when embedded in DPPC lipid bilayers. Which of the following values (in A) would be the best estimate for the length of the hydrophobic region of PorinA1?O 38O 51O 31O 42O 38

Biological membranes are lipid bilayers, which provide structure to the cells. Biological membranes…

Answered: The activity of a pore-forming membrane…

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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Given the melting profile of a membrane bilayer consisting of (see attached diagrams)where R = palmitate (16:0), (see graph) where the x-axis is temperature in °C andthe y-axis is the degree of fluidity (highervalue means the membrane is morefluid), in what direction does the curveshift if:a. the palmitate were replaced with oleate (18:1)b. the palmitate were replaced with stearate (18:0)c. the choline head group is replaced with –OCH2 CH3
The carbon–carbon bond distance for single-bonded carbons such as those in a saturated fatty acyl chain is about 1.5 Å. Estimate the length of asingle molecule of palmitate in its fully extended form. If two molecules of palmitate were placed end to end, how would their total length compare with the thickness of the lipid bilayer in a biological membrane?
A spherical cell with the diameter of 10uMhas a protein concentration of 20 mg/ml. Determine the number of protein molecules within the cell if the molecular weight of an average protein is 50,000 daltons (g/mol). Recall that Avogadro's number is NA 6.0221367×1023 molecules/mol. =
Of the following cell membrane lipids, which one prefers to reside in the inner leaflet (or inner half) of the membrane bilayer, AND has an overall neutral charge at physiological pH (7.4)? a) PE (phosphatidylethanolamine) is inner-leaflet with an overall neutral charge at pH 7.4 b) SM (sphinogomyelin) is inner-leaflet with an overall neutral charge at pH 7.4 c) PS (phosephatidylserine) is inner-leaflet with an overall neutral charge at pH 7.4 d) PC (phosphatidylcholine) is inner-leaflet with an overall neutral charge at pH 7.4
yeasts are able to produce high internal concentrations of glycerol to counteract the osmotic pressure of the surrounding media. suppose that a sample of yeast cells were placed in a 4% sodium chloride solution by weight. The density of solution is at 25 C = 1.02 g/ml, Molecular weight of solute = 58.44 g/mol, i of glycerol = 1 and R=0.08205 L-atm/mol-K What is the weight of solute in grams What is the moles of solute What is the volume of the solution in liters What is the molarity of the solution What is the value of the temperature to be used to solved for the osmotic pressure of the solution What is the osmotic pressure of solution
The CMC of SDS is 8.2 mM at 25 °C. Please describe the biological membrane solubilization when [SDS] is below or above 8.2 mM in the solution.
Proteoglycan aggregates in tissues form hydrated, viscousgels. Can you think of any obvious mechanical reason whytheir capacity to form gels is important to cell function?[Hint: Liquid water is virtually incompressible.]
Suppose the major solutes in intact lysosomes are KCl (~0.1 M) and NaCl (~0.03 M). When isolating lysosomes, what concentration of sucrose is required in the extracting solution at room temperature (25oC) to prevent swelling and lysis? Calculate how much sucrose (342.3 g/mol) would you need to make 500 ml of this extracting solution.
Create a ROUGH SKETCH (no need for exact hydropathy indices and residue numbers) of the hydropathy plot for the given membrane protein. -coo Please follow the color assignment of the helical domains and properly label the plot and axes. Here is an example: Amino Outside terminus Transmembrane helices are predicted by hydrophobic stretches of 20-25 aa residues 10 50 100 150 200 250 Hydrophobic Inside Hydrophilic Carboxyl terminus -3 10 50 100 150 200 250 Residue number Bacteriorhodopsin Hydropathy index
Diffusion experiments of a small molecule drug in tissue samples are performed. The drug has a radius of 2.24 nm and a pure-water diffusivity of 2.75 x 10^-6 cm^2/s. Cells occupy approximately 72% of the tissue byvolume. The molecule is very hydrophilic and does not readily cross cellular membranes. If you assume that the interstitial space is gel-like with a microstructure parameter k=3.7 x 10^-3 nm^-1, what is the effective diffusivity in the tissue?
A series of standard proteins and an unknown enzyme were studied by gel filtration on a Sephadex G200 (the 200 refers to the maximum pore size in kDa) column. The elution volume Vel for each protein is given in Table 1 below. (a) Plot the data in the form of log Mr versus elution volume. From the line of best fit through the points for the standards, determine the Mr of the unknown enzyme. Explain why ferritin and ovomucoid behave anomalously. Table 1 - The Vel versus Mr data Protein Mr Vel (mL) Blue dextran* Lysozyme Chymotrypsin Ovalbumin Serum albumin Aldolase Urease Ferritin# Ovomucoid# Unknown 1,000,000 14,000 25,000 45,000 68,500 150,000 500,000 700,000 28,000 ⎯ 85 200 190 170 150 125 90 92 160 139 *Blue dextran is not a protein but a high-Mr carbohydrate that has a covalently bound blue dye, and it elutes with the void volume of the column. # Do not…
Which of the following cell membrane lipids prefers to reside in the INNER leaflet (or inner half) of the membrane bilayer, AND is NOT zwitterionic at physiological pH (7.4)? O PS (phosphatidylserine) is inner-leaflet & NOT zwitterionic SM (sphingomyelin) is inner-leaflet & NOT zwitterionic O PC (phosphatidylcholine) is inner-leaflet & NOT zwitterionic 3 of these 4 responses are correct O PE (phosphatidylethanolamine) is inner-leaflet & NOT zwitterionic

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