Concept explainers
Answers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book.
(Research Problem) Conformational Transitions in Proteins How do proteins accomplish conformational changes? How is it that proteins convert precisely and efficiently from one conformation to another'.’ Recall from Figure 6.54 that any folding/unfolding transition must involve movement across a free-energy landscape, and try to imagine the nature of a conformational transition. Are bonds formed and broken along the way'.' What kinds of bonds and interactions might be involved? Suggest how such conformational transitions might occur. One reference that will be useful in this regard is:
Boehr. D.. 2009. During transitions proteins make fleeting bonds. Cell 139: 1049-1051.
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Study Guide With Student Solutions Manual And Problems Book For Garrett/grisham's Biochemistry, 6th
- Geranylgeranyl pyrophosphate 5 is converted by general acid-base catalysis to 6, and then to the natural product 7. For clarity only limited atom numbers are shown, but the main chain carbons are numbered 1 to 16, and the off-chain methyl substituents are numbered 17-20. A. Based on what you specified in A, use curly arrows on the drawing above to convert 5 to 6, and 6 to 7. Invoke general acids and general bases as needed, and draw in hydrogens as necessary . B. On the structure of 7, write in the atom numbers for the carbons marked with an asteriskarrow_forwardα-Pinene (4) is synthesized enzymatically from nerol pyrophosphate 1. Drawn an arrow-pushing mechanism from 1 to 2 to 3 to 4; add explicit hydrogens to clarify, if needed.arrow_forwardA reverse phase column chromatography separates proteins according to their polarity. Which pentapeptide will be eluted FIRST when chromatographed at pH 7 using a reverse phase column such as a C-18 column? Peptide Sequence (from N-terminal to C-terminal) AKGED GAAVF ALLLI MCYAG GAAVF MCYAG ALLLI AKGEDarrow_forward
- Melting of three DNA samples with varying lengths was monitored by increase of ultraviolet light absorbance at 260 nm. Which is the shortest DNA? A B Carrow_forwardSelect the CORRECT description of the peptide bond. The peptide bond can freely rotate around the peptide bond. The peptide bond is non-polar, hydrophobic and does not have a dipole. The peptide bond is most stable in the cis configuration. The peptide bond is rigid and planar. The peptide bond has a mix of single and double bond characters. The peptide bond is most stable in the trans configuration.arrow_forwardBelow is a fractional saturation curve for O2 binding to adult hemoglobin. Assume that curve Y represents a system at pH 7.4 and with a normal physiological level of 2,3-BPG. Curve Z represents a system that ___________________ Curve Z: is at pH 7.4 with a higher than normal physiological level of 2,3-BPG. is at pH 7.4 with a normal physiological level of 2,3-BPG but with a decreased level of CO2. has a higher pH with a normal physiological level of 2,3-BPG. has a higher pH with a lower than physiological level of 2,3-BPG.arrow_forward
- Which is a homotropic positive effector of aspartate transcarbamoylase (ATCase)? oxygen CTP aspartate ATParrow_forwardThe reaction scheme shows the mechanism of chymotrypsin-catalyzed peptide hydrolysis. Select ALL CORRECT statements regarding the chymotrypsin mechanism. Serine is the nucleophile in the step 3. Histidine is a general base in the step 2. Carbonyl carbon is the electrophile in the step 3. Histidine is a general acid in the step 4. Carbonyl carbon is the nucleophile in the step 3. This is an example of covalent catalysis. Aspartate is the electrophile in the step 3. Histidine is the nucleophile in the step 3.arrow_forwardThe following shows a protein with mostly beta sheet secondary structures. Which force stabilizes the beta sheet secondary structure of proteins? hydrophobic interactions between nonpolar amino acid side chains within the protein. electrostatic interactions between lysine and aspartic acid residues within the protein. hydrogen bonding between hydrogen bond donors and hydrogen bond acceptors of the peptide backbone. covalent disulfide linkages between cysteine residues within the protein.arrow_forward
- The Lineweaver-Burk plot was obtained when enzyme inhibition study was done in the absence and presence of 0.50 mM inhibitor. Answer the following questions using correct units and significant figures: (a) What is the mode of inhibition, competitive, uncompetitive, mixed, or noncompetitive? Explain your answer. (b) What can you say about the finding site for the inhibitor in relation to the active site of the enzyme? Explain your answer. (c) Calculate the Km and Vmax in the absence of inhibitor. (d) Calculate the Km and Vmax in the presence of 0.50 mM inhibitor. (e) Calculate the KI of the inhibitor using the given equations for reversible inhibition. Which has a higher affinity, the substrate or the inhibitor? How can you tell?arrow_forwardWhich peptide sequence is most likely to be found in the interior portion of a water-soluble globular protein? GGDGEMG DSKSTEG GAIVLWL IVAKSLIarrow_forwardThe following shows a reaction coordinate diagram. Choose a CORRECT statement explaining the diagram. The size of C decreases in the presence of an enzyme. B indicates the activation energy of the reaction in the presence of an enzyme. C indicates the activation energy of the reaction in the presence of an enzyme. A is related to the equilibrium constant of the reaction in the absence of an enzyme.arrow_forward
- BiochemistryBiochemistryISBN:9781305577206Author:Reginald H. Garrett, Charles M. GrishamPublisher:Cengage Learning