Question

1. Protein kinases phosphorylate target enzymes and as a result enzymes become activated or inactivated. Which of the statements are TRUE? (Multiple answers: You can select more than one option)

A. Phosphorylated enzymes behave like competitive inhibitors

B The presence of a phosphate acts as a non-competitive inhibitor/activator. No change in Km but significant change in Vmax

C. The presence of a phosphate group induces a conformational change that modifies the affinity and catalytic ability of a target enzyme

D. The presence of a phosphate group induces a conformational change that modifies the affinity of the binding site of a target enzyme

2. Two molecules are similar but not identical in structure and affect enzyme activity differently. Identify the statements that are TRUE?

(Multiple answers: You can select more than one option)

A. If both molecules are catalyzed by the same enzyme at different Vmax and Km they are both substrates

B. If one molecule is catalyzed and the other not but interferes with Vmax and Km the second molecule is an inhibitor

C the substrate that has the lowest Km is likely to have a better fit with the binding site of the enzyme

D. the substrate that has a higher Vmax definitely has a lower Km

E. the substrate that has lower Vmax definitely has a lower Km

3. Which of the statements about binding and active sites are TRUE?

Multiple answers: You can select more than one option

A. a binding site recognizes the substrate and the active site catalyses the reaction

B. a binding site catalyses the reaction and active site activates the reaction

C.binding and activation sites are the same

D. a binding site interacts with the substrate and the active sites makes sure the substrate is a perfect fit

E. a binding site provides specificity to enzyme substrate interactions

4. Endoglucanases and cellobiohydrolases have the same catalytic center but have a variant configuration of the binding site. Identify, which of the following is TRUE?

Multiple answers: You can select more than one option

A. Because the catalytic site is identical but the binding site different both enzymes are capable of interacting with the substrate in different ways thus producing different catalytic products

B. Because both enzymes have different binding sites they catalyses different glycosidic bonds

C. While endoglucanase cuts the substrate in the middle of the polymer because it has an open cleft binding site cellobiohydrolase nibbles at the ends of the polymer because it has a tunnel like binding site

D. Both enzymes are beta glucanases therefore their functions are identical

Answer 1

1 o) The presence of a phosphate group induces a confirmational change that modifies the affinity and catalytic ability of a target enzyme. 2) c) The substrate that has lowest Km is likely to have a better fit with the I binding site of the enzyme. ) Binding and activation sites are ) Both enzymes are betan glucan ases therefore their functions are identical and Lare 3 4 iame .

() while endoglucanase cuts the substrate in the middle of the polymer because it has an open cuft binding site cello Giohydrolase nibbles at the ends of the polymer because it has a tunnel lela binding site - option D is correct only of the endo glucanase is ß form.