The enzyme glucose oxidase, isolated from the mold *Penicillium notatum*, catalyzes the oxidation of β-D-glucose to D-glucono-δ-lactose. 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 by glucose 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 non-enzymatic oxidizing agents like Tollens reagent?*Is β-D-glucosamine a reducing sugar?*

Carbohydrates are polyhydroxy aldehydes or ketones. They can be classified as monosaccharides,…

Answered: *The enzyme glucose oxidase isolated…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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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−.
Azathioprine is an immunosuppressant drug used in kidney transplants. In vivo, azathioprine is metabolized to the hypoxanthine analog 6- mercaptopurine, which is then converted into 6-mercaptopurine ribose monophosphate, the active form of the drug. 6- Mercaptopurine ribose monophosphate also inhibits de novo purine synthesis, reducing uric acid levels in the blood and urine. However, when administered to Lesch – Nyhan patients, there was no effect on uric acid levels. Explain why this is the case.
Consider the biochemical pathway shown here. Suppose that a strain of bacteria must synthesize compound 4 to survive and divide. Successful survival and division of bacteria is observed as growth of colonies on an agar plate. This strain of bacteria can grow colonies on minimal medium as long as it is supplemented with compound 1. You are in a lab that has isolated several mutants of this strain. You find that these mutants cannot grow on minimal medium supplemented with compound 1, though they can grow colonies if supplemented with compound 4. Considering what you know about the Beadle-Tatum experiments, which of the following statements would be one that should be true?
Equation 7a of the text, (Umax/KM1) [S] (v'max/KM2) [P] 1+ [S]/KM1 + [P]/KM2 - gives the expression for the rate of formation of product by a modified version of the Michaelis-Menten mechanism in which the second step is also reversible. Derive the expression and find its limiting behaviour for high and low concentrations of substrate.
The purified OXA-M290 enzyme can now be tested to determine which β-lactamase inhibitor is most effective. This inhibitor could be prescribed in combination with a β-lactam antibiotic to treat the infection caused by the E. coli KGH1 strain. Before testing inhibitors against OXA-M290, the kinetic activity of this enzyme must first be measured. The activity of OXA-M290 is measured using nitrocefin, a chromogenic β-lactam antibiotic. When nitrocefin is hydrolyzed by a β-lactamase, it changes from yellow to red in colour. The nitrocefin hydrolysis product has an extinction coefficient of 20,500 M-1 cm-1 at 486 nm. The hydrolysis of 60 μM nitrocefin by 1 nM OXA-M290 is monitored using a microplate reader. The absorbance of the wells in the plate is measured at 486 nm every 30 seconds. This experiment is carried out with three replicates, generating the following data: Time (min) Absorbance of Replicate 1 Absorbance of Replicate 2 Absorbance of Replicate 3 0.5 0.0984…
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Why is de novo biosynthesis of purines markedly elevated in patients with a deficiency in hypoxanthine-guanine phosphoribosyl transferase (HGPRT)? 5-Fluoruracil is converted to methotrexate by a DPD deficiency, leading to increased purine biosynthesis. HGPRT deficiency prevents purine salvage, leading to increased purine biosynthesis to make up for it. HGPRT increases pyrimidine salvage and thereby increases purine biosynthesis as a result. Increased purine biosynthesis is the result of ATP hydrolysis during the production of cyclic AMP.
Since all of the ββ-lactams that you have tested are susceptible to hydrolysis by PaESBL-1, the hospital will not be able to use a single ββ-lactam to combat this P. aeruginosa isolate. You need to consider alternative strategies. From the following list, select all of the strategies that might successfully overcome the broad substrate specificity of PaESBL-1:
iii only
The ABO blood group antigens are the terminal sugars covalently linked to the end of the glycolipid in the red blood cellmembrane. The H antigen is the precursor of the A and Bantigens. Individuals with type A blood produce a gene thatcodes for an enzyme that adds N-acetylgalactosamine in ana(1,3) linkage to the Gal* residue in the H antigen. Type Bblood requires that an enzyme add a d-a galactose in an a(1,3) linkage to the Gal*. Draw the structures of the A andB antigens.
Since all of the B-lactams that you have tested are susceptible to hydrolysis by PAESBL-1, the hospital will not be able to use a single 8-lactam to combat this P. aeruginosa isolate. You need to consider alternative strategies. From the following list, select all of the strategies that might successfully overcome the broad substrate specificity PAESBL-1: Check all that apply. using multiple B-lactams simultaneously (e.g., rather than treating with amoxicillin alone, treat with the three B-lactams: amoxicillin, cephalothin, and imipenem). O using a reversible inhibitor of PAESBL-1 instead of a 8-lactam. Treat future infections by O combining a reversible inhibitor of PAESBL-1 with one or more 8-lactams. O using an irreversible inhibitor of PaESBL-1 instead of a B-lactam. O combining an irreversible inhibitor of PAESBL-1 with one or more -lactams. O O O O
Indicate the presence of the the B galactosidase and permease. Please explain and follow the instructions in the picture

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