3. (a)The activity of the Pentose Phosphate Pathway is commonly quantified by measuring14CO2 production from C-14 labeled glucose. In this assay, glucose is metabolized aerobically by cellsor tissue slices; both [1-14C] glucose and [6-14C] glucose are employed separately but in parallel. Thisclassical method, thus, requires two separate assay mixtures. Which radioactive isotopomer of glu-cose releases 14 CO2 generated by the Pentose Phosphate Pathway? Confirm your conclusion bydrawing the intermediates of the oxidative phase of the PPP with structural formulas, starting withglucose-6-phosphate. Name the intermediates and indicate enzymes.(b) (Because the assay protocolrequires aerobic incubation of cells or tis-sue slices with isotopically labeled glucosein parallel assays, what is the purpose ofthe other radioactive glucose derivative?To answer this question base your answerusing the diagram on the right.O + 2 NADHCH₂OH+ 2 NAD+○HOHO+ 2 Pi2CO+ 2 ATPHOOH 2 ADPCH3+ 2 H₂OGlucosePyruvate

To further understand the utilization of [1-14C]glucose and [6-14C]glucose in the test and the…

Answered: 3. (a) The activity of the Pentose…

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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3. (a) The activity of the Pentose Phosphate Pathway is commonly quantified by measuring 14CO2 production from C-14 labeled glucose. In this assay, glucose is metabolized aerobically by cells or tissue slices; both [1-14C] glucose and [6-14C] glucose are employed separately but in parallel. This classical method, thus, requires two separate assay mixtures. Which radioactive isotopomer of glu- cose releases 14 CO2 generated by the Pentose Phosphate Pathway? Confirm your conclusion by drawing the intermediates of the oxidative phase of the PPP with structural formulas, starting with glucose-6-phosphate. Name the intermediates and indicate enzymes. (b) ( Because the assay protocol requires aerobic incubation of cells or tis- sue slices with isotopically labeled glucose in parallel assays, what is the purpose of the other radioactive glucose derivative? To answer this question base your answer using the diagram on the right. O2 NADH CH₂OH + 2 NAD+ HO HO + 2 Pj 2 CO + 2 ATP HO OH 2 ADP CH3…
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 B-D-glucose to D-glucono-6-lactone. The enzyme is highly specific for the B anomer of glucose and does not affect the a anomer. In spite of this specificity, the reaction catalyzed by glucose oxidase is commonly used in a clinical assay for total blood glucose -that is, for solutions consisting of a mixture of B- and a-D-glucose, as well as other sugars present in blood. The oxidation proceeds in the presence of oxygen and forms hydrogen peroxide, in addition to the lactone. A second enzyme, called peroxidase, catalyzes the reaction of hydrogen peroxide with colorless compounds to create a colored product, which is quantified with a simple spectrophotometer. 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 the Fehling's reagent for measuring blood glucose?
*The enzyme glucose oxidase isolated from the mold Penicillium notatum catalyzes the oxidation of 3-D-glucose to D-glucono-6- lactose. This enzyme is highly specific for the ß anomer of In spite of this glucose and does not affect the a anomer. specificity, the reaction catalyzed by glucose oxidase is commonly used in a clinical assay for total blood glucose that is, for solutions consisting of a mixture of 3- and a-D- glucose. What are the circumstances required to make this possible? Aside from allowing the detection of smaller quan- tities of glucose, what advantage does glucose oxidase offer over non-enzymatic oxidizing agents like Tollens reagent? *Is B-D-glucosamine a reducing sugar?
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.
A solution of [U 14C] glucose-1-phosphate (specific activity = 16,000 cpm/mmole) was incubated with glycogen and glycogen phosphorylase, an enzyme which adds glucose units on to glycogen. Radioactivity was incorporated into the glycogen primer at a rate = 2550 cpm/min. The rate of the enzymatic reaction in units of mmole glucose incorporated per minute is: (a) 0.016 mmol/min (b) 0.57 mmol/min (c) 0.16 mmol/min (d) 5.7 mmol/min
b. 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. Denote the point in the pathway in which each individual is blocked.
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.
EGTA (ethylene glycol-bis(β-amino ethyl ether)-N,N,N′,N′-tetraacetic acid) is a chelating agent with high affinity and specificity for Ca2+. By microinjecting acell with an appropriate Ca2+-EGTA solution, an experimenter can prevent cytosolic [Ca2+] from rising above 10+7 M. How would EGTA microinjection affect a cell’s response to vasopressin ? To glucagon?
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?
The activity of the enzyme β-galactosidase produced bywild-type cells grown in media supplemented with different carbon sources is measured. In relative units, thefollowing levels of activity are found:Glucose Lactose Lactose + glucose0 100 1Predict the relative levels of β-galactosidase activity incells grown under similar conditions when the cells arelacI−, lacIS, lacO+, and crp−.

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