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Question Description:

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1.TheformationofC+DfromA+Bhasanequilibriumconstantof0.1.WhatconcentrationofAwouldberequiredtoensure99%conversionofBtoproduct? How many different charge states are available to lysine a) as a free amino acid b) as a residue in a polypeptide? What would be the charge state of a C-terminal lysyl residue in a peptide at pH 2? Where would you expect to find lysine residues in a protein and why? 2. Malate dehydrogenase and succinic dehydrogenase both catalyse oxidative reaction in the Krebs Cycle. One uses NAD+ and the other uses FAD as cofactor. What is the difference in the mode of action of these two cofactors? Which is the stronger oxidant and why is it not employed for both reactions? Two different enzyme proteins (isoenzymes) catalyse the same reaction. Reaction mixtures to study the kinetics are set up using the same amount of enzyme protein in every case. Isoenzyme A gives a Km of 1mM and a Vmax of 5M/min. Isoenzyme B gives a Km of 0.1mM and a Vmax of 2M/min. Which of these enzymes gives the higher rate with 0.2mM substrate? With 2.0mM substrate? At what substrate concentration would both enzymes give exactly the same rate? 3. The enzyme glutamate-pyruvate aminotransferase has a pyridoxal phosphate (PLP) prosthetic group. Glutamate is the amino donor in the reaction and passes on the amino group to PLP, converting it to pyridoxamine phosphate. How is it possible to reconcile this with the idea that a catalyst remains chemically unchanged at the end of the reaction?

Answer

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