Concept explainers
(a)
To determine: An explanation to mutation in LDH which replaces Arg109 with Gln and shows 5% of pyruvate binding and 0.07% wild-type enzyme activity.
Introduction:
Mutation in an organism is defined as a permanent alteration of “
(b)
To determine: The reason why it is a surprising effect when the mutant form of LDH in which Arg171 is replaced with Lys shows only 0.05% of the wild –type level of substrate level binding.
Introduction:
Amino acids are building blocks of proteins. It is an organic compound that contains an
(c)
To explain: The effect of substituting Arg171with Lys.
Introduction:
Amino acids are building blocks of proteins. It is an organic compound that contains an amine group and carboxyl group along with a functional R group. It is involved in the regulation of several cellular processes of the body.
(d)
To explain: The reason why the mutant form of LDH in which Ile250 is replaced by Gln shows reduced binding of NADH.
Introduction:
Lactate dehydrogenase is a type of enzyme which is found in all living organisms including plants, animals and other prokaryotes. It is involved in the conversion of lactate into pyruvic acid in a cell.
(e)
To sketch: The active site of mutant LDH with oxaloacetate bound.
Introduction:
Lactate dehydrogenase is a type of enzyme which is found in all living organisms including plants, animals and other prokaryotes. It is involved in the conversion of lactate into pyruvic acid in a cell.
(f)
To determine: The use of oxaloacetate by mutant enzyme as a substrate instead of pyruvate.
Introduction:
Oxaloacetate is an organic compound and is an intermediate of citric acid cycle which reacts with acetyl-CoA to form citrate. The enzyme involved in this conversion is citrate synthase.
(g)
To explain: The statement that substituting a larger amino acid in the active site allowed a larger substrate to bind.
Introduction:
Amino acids are building blocks of proteins. It is an organic compound that contains an amine group and carboxyl group along with a functional R group. It is involved in the regulation of several cellular processes of the body.

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Chapter 6 Solutions
Lehninger Principles of Biochemistry (Instructor's)
- To map the active site of -lactamase, the enzyme was hydrolyzed with trypsin to yield a hexapeptide (P1) with the following amino acids. Glu, Lys, Leu, Phe, Met, and Ser. Treatment of P1 with phenyl isothiocyanate yielded a PTH derivative of phenylalanine and a peptide (P2). Treatment of P1 with cyanogenbromide gave an acidic tetrapeptide (P3) and a dipeptide (P4).Treatment of P2 with 1-fluoro-2,4-dinitrobenzene, followed by complete hydrolysis, yields N-2,4-dinitrophenyl-Glu. P1, P2, and P3 contain the active site serine. question: the b-lactamase hydrolyzes the lactam-ring in antibiotics like penicillin. Describe the mechanism, of hydrolysis, insuring to include the involvement of S, D, and K in the reaction sequence. Please help!arrow_forwardThree of these amino acids participate in the proteolytic hydrolysis of polypeptides. Show the charge-relay network generated by the serine proteases and identify the nucleophilic species that initiates the hydrolysis. please help!arrow_forwardYou have isolated a protein and determined that the native molecular weight of the holoenzyme is 160 kD using size exclusion chromatography. Analysis of this protein using SDS-PAGE revealed 2 bands, one at 100 kD and one at 30 kD. 1. Describe the architecture of the polypeptide component of this enzyme. 2. The enzyme was found to be 0.829% NAD (by weight). What further can be said regarding the architecture? can you please help me with question number 2arrow_forward
- To map the active site of -lactamase, the enzyme was hydrolyzed with trypsin to yield a hexapeptide (P1) with the following amino acids. Glu, Lys, Leu, Phe, Met, and Ser. Treatment of P1 with phenyl isothiocyanate yielded a PTH derivative of phenylalanine and a peptide (P2). Treatment of P1 with cyanogenbromide gave an acidic tetrapeptide (P3) and a dipeptide (P4).Treatment of P2 with 1-fluoro-2,4-dinitrobenzene, followed by complete hydrolysis, yields N-2,4-dinitrophenyl-Glu. P1, P2, and P3 contain the active site serine. Question: although S, K, and D are involved in the catalysis, the E in this hexapeptide does not participate in the hydrolysis of the b-lactam ring. Why is that?arrow_forwardTo map the active site of beta-lactamase, the enzyme was hydrolyzed with trypsin to yield a hexapeptide (P1) with the following amino acids. Glu, Lys, Leu, Phe, Met, and Ser. a) Using the experimental results described below deduce the primary sequence of the active site hexapeptide. Treatment of P1 with phenyl isothiocyanate yielded a PTH derivative of phenylalanine and a peptide (P2). Treatment of P1 with cyanogenbromide gave an acidic tetrapeptide (P3) and a dipeptide (P4).Treatment of P2 with 1-fluoro-2,4-dinitrobenzene, followed by complete hydrolysis, yields N-2,4-dinitrophenyl-Glu. P1, P2, and P3 contain the active site serine. please help!arrow_forwardThe beta-lactamase hydrolyzes the lactam-ring in penicillin. Describe the mechanism of hydrolysis, insuring to include the involvement of S, D, & K in the reaction sequence. Please helparrow_forward
- To map the active site of beta-lactamase, the enzyme was hydrolyzed with trypsin to yield a hexapeptide (P1) with the following amino acids. Glu, Lys, Leu, Phe, Met, and Ser. Treatment of P1 with phenyl isothiocyanate yielded a PTH derivative of phenylalanine and a peptide (P2). Treatment of P1 with cyanogenbromide gave an acidic tetrapeptide (P3) and a dipeptide (P4).Treatment of P2 with 1-fluoro-2,4-dinitrobenzene, followed by complete hydrolysis, yields N-2,4-dinitrophenyl-Glu. P1, P2, and P3 contain the active site serine. Why doesn't D in this hexapeptide not participate in the hydrolysis of the beta-lactam ring even though S, K, and D are involved in the catalyst?arrow_forwardTo map the active site of -lactamase, the enzyme was hydrolyzed with trypsin to yield a hexapeptide (P1) with the following amino acids. Glu, Lys, Leu, Phe, Met, and Ser. Treatment of P1 with phenyl isothiocyanate yielded a PTH derivative of phenylalanine and a peptide (P2). Treatment of P1 with cyanogenbromide gave an acidic tetrapeptide (P3) and a dipeptide (P4).Treatment of P2 with 1-fluoro-2,4-dinitrobenzene, followed by complete hydrolysis, yields N-2,4-dinitrophenyl-Glu. P1, P2, and P3 contain the active site serine. Using the experimental results described above derive the primary sequence of the active site hexapeptide. Please help!arrow_forwardWhich type of enzyme catalyses the following reaction? oxidoreductase, transferase, hydrolase, lyase, isomerase, or ligase.arrow_forward
- +NH+ CO₂ +P H₂N + ATP H₂N NH₂ +ADParrow_forwardWhich type of enzyme catalyses the following reaction? oxidoreductase, transferase, hydrolase, lyase, isomerase, or ligase.arrow_forwardWhich features of the curves in Figure 30-2 indicates that the enzyme is not consumed in the overall reaction? ES is lower in energy that E + S and EP is lower in energy than E + P. What does this tell you about the stability of ES versus E + S and EP versus E + P.arrow_forward
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