Concept explainers
Cartoon renderings of the proteins Top 7 and adaH2 are shown below. Both are soluble, densely packed proteins of roughly 96 residues, and each has a topology of 2 a helices packed onto a 5-stranded ß sheet.
The accompanying table lists some information about the amino acid composition and values of ΔS0 for the folding of these proteins (i.e. for Unfolded →Folded) at 250C. Based on the information in the table, which protein do you predict buries the greater hydrophobic surface area upon folding? Assume 2-state folding (i.e., no intermediates), and that the Unfolded state for both proteins is 100% solvent-exposed. Explain your answer in terms of expected contributions from ΔS0peptide and ΔS0solvent.
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Biochemistry: Concepts and Connections (2nd Edition)
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- Which intermolecular forces are important in acetic acid, CH3 –(C=0)-oh? A particular amino acid contains a- CHNH3+ group. Is this amino acid more likely to be found on the inside or the outside of the folded protein? Briefly explain. The addition of ethanol, CH3CHOH, t an aqueous solution lowers the surface tension of the solution. Predict whether adding ethanol to an aqueous protein solution will tend to stabilize or unfold the protein. Briefly explain.arrow_forwardDo you expect a Pro → Gly mutation in a surface-loop region of a globular protein to be stabilizing or destabilizing? Assume the mutant folds to a native-like conformation. Explain your answer in terms of the predicted enthalpic and entropic effects of the mutation on the AG for protein folding compared to AG of folding for the wild-type protein.arrow_forwardProtein concentration can readily be determined using the Beer-Lambert law: A = e l c where A = absorbance e = molar absorption coefficient (M-1cm-1) l = light path length (cm) c = concentration (M) If the molar absorption coefficient at 280 nm for yeast ADH is 48860 M-1cm-1 and a 10 mL solution of the protein has an absorbance at 280 nm of 0.4 (as measured by a spectrometer with pathlength 1 cm), then what is the concentration of the protein solution (in μM)? i.e. concentration = ______ μM If the molecular weight of the protein is 36849, what is its concentration in mg/mL? i.e. concentration = _______ mg/mL For each part of the question, show your calculations to arrive at your answers.arrow_forward
- The major difference between a protein molecule in its native state and in its denatured state lies in the number of conformations available. To a first ap- proximation, the native, folded state can be thought to have one conforma- tion. The unfolded state can be estimated to have three possible orientations about cach bond between residues. (a) For a protein of 100 residues, estimate the entropy change per mole upon denaturation. (b) What must be the enthalpy change accompanying denaturation to allow the protein to be half-denatured at 50 °C? (c) Will the fraction denatured increase or decrease with increasing temperature?arrow_forwardTERTIARY STRUCTURE (A) (B) (C) Fg Eet Galand Sen 20e Figure 6. Examples of the arrangement of a-helices and B-sheets in folded protein domains. Copyright 2013 from Essential Cell Biology, 4th Edition by Alberts et al. Reproduced by permission of Garland Science/ Taylor & Francis LLC. Figure 6 shows three examples of how secondary structure elements can be arranged in relation to one another in the functional, folded form of a complete protein or one compact portion of a protein. The overall three-dimensional shape (or conformation) of a protein is its tertiary structure. • What do you think holds together the various secondary structural elements in a particular three-dimensional pattern? (Hint: Look back at Figure 5 - what is sticking out from the sides of the a-helices and B-strands?)arrow_forwardLoop regions play important roles in the secondary structure of protein. Define loop region and give three (3) of the rolesarrow_forward
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