You perform Michaelis-Menten kenetics on i) trypsin and ii) a mutant form of the same enzyme (a single amino acid has been changed). The specificity constant for the mutant was 10 times larger than for trypsin. a) Define the specificity constant and explain using this definition how a larger value might occur. b) Explain how, if at all, a non-competitive inhibitor of trypsin would affect the specificity constant.

What is the molecular basis for methicillin resistance in certain strains of S. aureus (MRSA)?

For a Michaelis-Menten enzyme, k1 = 5.2 ⅹ 108 M-1 s -1 , k-1 = 3.1 ⅹ 104 s -1 , and k2 = 3.4 ⅹ 105 s -1 . a) Write out the reaction, showing k1, k-1, and k2. Calculate Ks and Km. Does substrate binding approach rapid equilibrium or the steady state? Show work justify b) What is kcat for this reaction? Show work justify c) Calculate Vmax for the enzyme. The total enzyme concentration is 25 pmol L-1 , and each enzyme has two active sites.

Consider the following set of data and answer the fo

In biochemical and structural terms, how does the cellular form of the prion protein differ from the infectious form? Can you also explain what is the biochemical basis for “infectiousness” of the prion protein?

Vitamin K questionsa) What transformation of glutamate side chains is Vitamin K (as its reduced form, VitaminKH2) involved in, and what is the relevance of this reaction to blood clotting?b) How does the blood thinner Coumadin (warfarin) prevent clotting?c) How can the dietary intake of large amounts of green vegetables, such as broccoli or kaleinterfere with the action of Coumadin?

Enzyme X has a molecular weight of 48,000. It converts substrate Z into product Y. Z absorbs at 340 nm, and Y absorbs at 480 nm.    A.) At what wavelength would you measure the change in absorbance to assay for enzyme X? Would the absorbance increase or decrease over time?   B.)If Vmax = 60 μmol/min and you used 400 μL of a 0.1 mg/mL solution of enzyme, what is the turnover number?

A. Which one of the following is an example of affinity chromatography? Select all that apply. a) Hormone – receptor interaction b) Enzyme – substrate interaction c) Antigen-antibody interaction d) All of the above e) Cytochrome C – DEAE matrix B. If your sepharose beads are covalently attached to adrenaline hormone, which of the following protein is most likely purified by affinity chromatography? a) Receptor tyrosine kinase (RTK) b) Calmodulin c) GPCR d) Protein kinase A C. Which of the following malate dehydrogenase (MDH) has a 'peptide epitope tag'? a) MDH-HA b) MDH-GST c) MDH-GFP e) All of them D. To elute target proteins from an affinity chromatography matrix, which of the following conditions would be the most appropriate? a) Low salt concentrations b) High salt concentrations c) Adding a soluble ligand that competes with the affinity tagged protein for binding to the column d) Just keep washing buffer through the column, isocratic elution

One can identify phenylketonurics and PKU carriers (heterozygotes) by means of a phenylalanine tolerance test. One injects a large dose of phenylalanine into the bloodstream and measures its clearance from the blood by measuring serum phenylalanine levels at regular intervals. Sketch curves showing relative blood phenylalanine concentration versus time that you would expect to be displayed by (a) a PKU patient, (b) a heterozygote, and (c) a normal individual. What kind of tolerance test could you devise to distinguish between PKU resulting from either phenylalanine hydroxylase deficiency or dihydropteridine reductase deficiency?

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?