學士後西醫-普通生物及生化概論題庫下載題庫

(B) Positive cooperativity implies allosteric binding – binding of the ligand at one site increases the enzyme's affinity for another ligand at a site different from the other site. Enzymes that demonstrate cooperativity are defined as allosteric.

(C) Hill plot of the Hill equation in red, showing the slope of the curve being the Hill coefficient and the intercept with the x-axis providing the apparent dissociation constant. The green line shows the non-cooperative curve

(D)Christian Bohr and the concept of cooperative binding

In 1904, Christian Bohr studied hemoglobin binding to oxygen...

(B) Positive cooperativity implies allosteric binding – binding of the ligand at one site increases the enzyme's affinity for another ligand at a site different from the other site. Enzymes that demonstrate cooperativity are defined as allosteric.

(C) Hill plot of the Hill equation in red, showing the slope of the curve being the Hill coefficient and the intercept with the x-axis providing the apparent dissociation constant. The green line shows the non-cooperative curve

(D)Christian Bohr and the concept of cooperative binding

In 1904, Christian Bohr studied hemoglobin binding to oxygen under different conditions. When plotting hemoglobin saturation with oxygen as a function of the partial pressure of oxygen, he obtained a sigmoidal (or "S-shaped") curve. This indicates that the more oxygen is bound to hemoglobin, the easier it is for more oxygen to bind - until all binding sites are saturated. 

Original figure from Christian Bohr, showing the sigmoidal increase of oxyhemoglobin as a function of the partial pressure of oxygen.

(E) Hill coefficient (nH) is a measure of cooperativity in a binding process. A Hill coefficient of 1 indicates independent binding, a value of greater than 1 shows positive cooperativity binding of one ligand facilitates binding of subsequent ligands at other sites on the multimeric receptor complex.