BIOCHEM ACS COMPREHENSIVE
ASSESSMENT 2026 COMPLETE
QUESTIONS AND ANSWERS
◉ HPLC, or high-performance liquid chromatography.
Answer: pumps speed the movement of the protein molecules down
the column, as well as higher-quality chromatographic materials
that can withstand the crushing force of the pressurized flow. By
reducing the transit time on the column, HPLC can limit diffusional
spreading of protein bands and thus greatly improve resolution.
◉ cation-exchange chromatography (3)
Answer: solid matrix (stationary phase) has negatively charged
groups. In the mobile phase, proteins with a net positive charge
migrate through the matrix more slowly than those with a net
negative charge. The two types of protein can separate into two
distinct bands.
◉ Induced fit
Answer: conformational changes (in either ligand or protein) that
can occur upon ligand binding in order for tighter binding of ligand.
ex: HbA
, ◉ porphin
Answer: organic compound that is aromatic and heterocyclic,
consisting of 4 pyrole rings joined by 4 methine (=CH-) groups to
form a larger macrocycle ring. Ex: hemoglobin
◉ hemoglobin, HbA (5)
Answer: sigmoidal curve (positive cooperativity); four subunits bind
four O2; binding one O2 increases affinity for binding the other three
(heme-heme interaction)
◉ ligand (5)
Answer: any molecule that binds reversibly to a protein
◉ myoglobin, Mb (5)
Answer: hyperbolic curve; one subunit binds one O2; higher affinity
for oxygen than HbA, binds oxygen dropped by HbA in low oxygen
environments (myo = muscle)
◉ Hill plot (5)
Answer: turns sigmoid into straight lines. slope = n (# of binding
sites). allows measurement of cooperative binding sites.
◉ Hill number, n/nH (chapter 5)
ASSESSMENT 2026 COMPLETE
QUESTIONS AND ANSWERS
◉ HPLC, or high-performance liquid chromatography.
Answer: pumps speed the movement of the protein molecules down
the column, as well as higher-quality chromatographic materials
that can withstand the crushing force of the pressurized flow. By
reducing the transit time on the column, HPLC can limit diffusional
spreading of protein bands and thus greatly improve resolution.
◉ cation-exchange chromatography (3)
Answer: solid matrix (stationary phase) has negatively charged
groups. In the mobile phase, proteins with a net positive charge
migrate through the matrix more slowly than those with a net
negative charge. The two types of protein can separate into two
distinct bands.
◉ Induced fit
Answer: conformational changes (in either ligand or protein) that
can occur upon ligand binding in order for tighter binding of ligand.
ex: HbA
, ◉ porphin
Answer: organic compound that is aromatic and heterocyclic,
consisting of 4 pyrole rings joined by 4 methine (=CH-) groups to
form a larger macrocycle ring. Ex: hemoglobin
◉ hemoglobin, HbA (5)
Answer: sigmoidal curve (positive cooperativity); four subunits bind
four O2; binding one O2 increases affinity for binding the other three
(heme-heme interaction)
◉ ligand (5)
Answer: any molecule that binds reversibly to a protein
◉ myoglobin, Mb (5)
Answer: hyperbolic curve; one subunit binds one O2; higher affinity
for oxygen than HbA, binds oxygen dropped by HbA in low oxygen
environments (myo = muscle)
◉ Hill plot (5)
Answer: turns sigmoid into straight lines. slope = n (# of binding
sites). allows measurement of cooperative binding sites.
◉ Hill number, n/nH (chapter 5)
