BIOC 3560 Quiz 1

Occupancy (theta) is equal to: a) All of the binding sites occupied/total binding sites b) All of the binding sites unoccupied/total binding sites c) All of the binding sites unoccupied/ all of the binding sites occupied d) All of the binding sites occupied/all of the binding sites unoccupied

a) All of the binding sites occupied/total binding sites

Which of the following is NOT a key concept in protein-ligand binding? a) Irreversible binding b) specificity c) conformational change d) Transient interactions

a) Irreversible binding

Protein 1 has KD = 0.09 mM for glucose, while Protein 2 has KD = 0.06 mM. What does this mean? a) Protein 2 binds substrate more tightly than Protein 1 b) Protein 1 binds substrate more tightly than Protein 2 c) Protein 2 has more binding sites than Protein 1 d) Protein 1 has more binding sites than Protein 2

a) Protein 2 binds substrate more tightly than Protein 1

Which of the following statements is the correct definition of an allosteric protein a) The binding of a ligand to one site affects the properties at another site b) The binding of a modulator is affected by ligand binding c) The binding of a ligand is affect by the binding of oxygen d) The binding of a ligand is not affected by the binding of oxygen

a) The binding of a ligand to one site affects the properties at another site*

Which of the following about globins is FALSE? a) Myoglobin is a monomer b) Hemoglobin is a pentamer c) Leghemoglobin is found in plants d) All globins carry oxygen e) They contain heme

b) Hemoglobin is a pentamer

A mutant form of hemoglobin uses disulphide bridges to stabilize the T-state instead of salt bridges. How would the behaviour of this mutant Hb differ from the regular version? a) The mutant would bind oxygen easier than the regular version b) The mutant would spend less time in the R-state than the regular version c) The mutant would resist CO poisoning less than the regular version d) The mutant would resist CO poisoning more than the regular version

b) The mutant would spend less time in the R-state than the regular version

Which of the following statements about heme is TRUE? a) Heme consists of protoporhyrin X & Fe2+ b) It causes oxygen to form highly unreactive oxygen species c) Heme with Fe2+ can bind O2 reversibly d) Fe3+ is never found in heme

c) Heme with Fe2+ can bind O2 reversibly*

When O2 binds to hemoglobin, which of the following structural changes occurs? a) There is a shift in the position of helix E b) An ion pair is formed by His HC3 c) An ion pair is formed by Asp FG1 d) An ion pair is broken by Lys C5

d) An ion pair is broken by Lys C5

Which of the following statements about hemoglobin is false? a) It is a tetramer b) It has 2 alpha chains c) It has 2 beta chains d) It has 2 gamma chains

d) it has 2 gamma chains

Which of the following statements about allosteric modulators is true? a) Positive heterotropic modulators bind to the active site b) Negative heterotropic modulators bind to the active site c) Positive modulators push the protein into the T-state d) Negative modulators push the protein into the R-state e) Positive & negative modulators change P50

e) Positive & negative modulators change P50