The enzyme glucose oxidase isolated from the mold Penicillium notatum catalyzes the oxidation of β-Dglucose to D-glucono-δ-lactone. This enzyme is highly specific for the β anomer of glucose and does not affect the α anomer. In spite of this specificity, the reaction catalyzed byglucose oxidase is commonly used in a clinical assay for total blood glucose—that is, for solutions consisting of a mixture of β- and α-D-glucose. What are the circumstances required to make this possible? Aside from allowing the detection of smaller quantities of glucose, what advantage does glucose oxidase offer over Fehling’s reagent for measuring blood glucose?

The enzyme glucose oxidase isolated from the mold Penicillium notatum catalyzes the oxidation of β-Dglucose to D-glucono-δ-lactone. This enzyme is highly specific for the β anomer of glucose and does not affect the α anomer. In spite of this specificity, the reaction catalyzed byglucose oxidase is commonly used in a clinical assay for total blood glucose—that is, for solutions consisting of a mixture of β- and α-D-glucose. What are the circumstances required to make this possible? Aside from allowing the detection of smaller quantities of glucose, what advantage does glucose oxidase offer over Fehling’s reagent for measuring blood glucose?

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter10: From Proteins To Phenotypes

Section: Chapter Questions

Problem 10QP: b. Compounds A, B, C, and D are known to be intermediates in the pathway for production of protein...

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a. Compounds A, B, C, and D are known to be intermediates in the pathway for production of protein E. To determine where the block in protein-E production occurred in each individual, the various intermediates were given to each individuals cel Is in culture. After a few weeks of growth with the intermediate, the cells were assayed for the production of protein E. The results for each individuals cells are given in the following table. A plus sign means that protein E was produced after the cells were given the intermediate listed at the top of the column. A minus sign means that the cells still could not produce protein E even after being exposed to the intermediate at the top of the column. Draw the pathway leading to the production of protein E.
Orotic aciduria is a rare hereditary disorder due to deficient orotate phosphoribosyltransferase and orotidine-5'-decarboxylase activities that are encoded by Uridylate (UMP) synthetase gene in de novo pyrimidine biosynthesis. The characteristic of this disorder is excessive excretion of orotic acid in urine. A mutation of UMP synthetase gene has been identified as R96G (at amino acid position 96, Arginine is changed to Glycine). In orotic aciduria, predict the consequences of deficient UMP synthetase by identifying which downstream enzyme missing its action. One of important molecules to be derived from pyrimidine biosynthesis is deoxycytidine triphosphate (dCTP) for DNA replication and repair. How is dCTP synthesized, include what enzymes and important intermediates in the pathway? 3. As thymidine triphosphate (dTTP) is needed for DNA replication and repair, what enzymes and intermediates are required to get dTTP
. In Figure 6-11,a. in view of the position of HPA oxidase earlier in thepathway compared to that of HA oxidase, would youexpect people with tyrosinosis to show symptoms ofalkaptonuria?b. if a double mutant could be found, would you expecttyrosinosis to be epistatic to alkaptonuria?
Pyridoxal phosphate (PLP) is a coenzyme for the enzyme ornithine aminotransferase. The enzyme was purified from cells grow in PLP = deficient media as well as from cells grown in media that contained pyridoxal phosphate. The stability of the two different enzyme preparations was then measured by incubating the enzyme at 37°C for different lengths of time and then assaying for the amount of enzyme activity remaining. The following results were obtained. (a) Why does the amount of active enzyme decrease with the time of incubation? (b) Why does the amount of enzyme from the PLP deficient cells decline more rapidly?
The M and H subunits of lactate dehydrogenase have very similar sizes and shapes but differ in amino acidcomposition. If the only difference between the two were that theH subunit had a glutamic acid in a position where the M subunithad a serine, how would the five isozymes of LDH separate on electrophoresis using a gel at pH 8.6?
What would be the effect on the activity of phosphofructokinase of the mutation of Asp103 to the unusual amino acid shown below? Explain in terms of actual structures of the side chains of Asp and this unusual amino acid.
The proximal histidine residues have been replaced by glycine residues by mutation of the cloned genes for both the α and β subunits of hemoglobin. With the tetrameric mutant hemoglobin (all subunits being mutant, α H F8 G, β H F8 G), it was found that the “proximal” coordination bonds to hemes in the mutant protein could be replaced by having the small molecule imidazole in the buffers. Oxygen binding curves for the tetrameric mutant hemoglobin were measured. A. The degree of cooperativity in oxygen binding for the mutant hemoglobin (with imidazole present) would be expected to 1) increase 2) decrease 3) not be affected) compared with the normal protein. B. Justify your answer to part A in terms of what you know about the structural basis of cooperativity in hemoglobin. C. How would the Hill coefficient for the mutant be expected to change compared with nH for normal hemoglobin, which is ~3?
Each of the hydroxyl groups of glucose can be methylated with reagents such as dimethyl sulfate under basic conditions. Explain how exhaustive methylation followed by the complete digestion of a known amount of glycogen would enable you to determine the number of branch points and reducing ends.
The enzymatic activity of PFK1 is generally measured by set- ting up a coupled enzyme assay system whereby aldolase, triose phos- phate isomerase, and glycerol-3-phosphate dehydrogenase are added to the assay mixture. For the latter enzyme, NADH is added and its change in concentration is readily monitored at 340 nm. Write the chain of reactions catalyzed by these enzymes using structural formulas, label substrates and products, and explain why the coupled en- zyme assay system leads to oxidation of NADH. While the chain of reac- tions is similar to those in glycolysis, there is a critical difference because of the dehydrogenase enzyme. Describe how this enzyme causes the chain of reactions to differ from those in glycolysis.
Bacterial species that are capable of synthesising the amino acid histidine do not need it in their growth medium. Histidine biosynthesis requires a specific enzyme, which we shall refer to as histidine synthetase. When these bacteria are supplemented with histidine in their growth media, they cease intracellular histidine synthesis. Propose three distinct regulatory mechanisms to account for why histidine production ends when histidine is present in the growth medium. To further investigate this phenomena, you analyse the quantity of intracellular histidine synthetase protein produced when cells are cultured with and without histidine. The quantity of this protein is same in both scenarios. Which regulatory mechanism makes sense in light of this observation?
Mutations in the Galactose-1-Phosphate Uridyl Transferase Gene Can you use RFLP to identify this mutation?
The specific activity of a pure preparation of pyruvate kinase (PK) assayed in the direction of pyruvate formation (forward direction) is 220 U/mg at 25 C and at pH 7.5. This form of PK is a homotetramer (MW 240,000) with one active site per subunit. What is the kcat for PK in the forward direction?