Protein Structure and Function Flashcards

What is the isoelectric point (pI) of a protein?

Answer: The pH at which the protein carries no net charge

The isoelectric point is the pH at which the net charge of the protein is zero, meaning positive and negative charges are balanced.

Chaperone proteins assist in which process?

Answer: Correct protein folding

Molecular chaperones bind to unfolded or misfolded proteins and provide a protected environment that facilitates correct folding, preventing aggregation.

Which prosthetic group is found in myoglobin and hemoglobin, enabling oxygen binding?

Answer: Heme group

The heme group contains an iron atom (Fe²⁺) coordinated within a porphyrin ring, which reversibly binds molecular oxygen.

The cooperative binding of oxygen to hemoglobin is best described by which model?

Answer: Concerted (MWC) model

The concerted (Monod-Wyman-Changeux) model proposes that all subunits switch simultaneously between T (tense, low affinity) and R (relaxed, high affinity) states.

2,3-Bisphosphoglycerate (2,3-BPG) affects hemoglobin oxygen binding by:

Answer: Decreasing oxygen affinity by stabilizing the T state

2,3-BPG binds in the central cavity of deoxyhemoglobin and stabilizes the low-affinity T state, promoting oxygen release to tissues.

Which technique separates proteins based on their isoelectric points?

Answer: Isoelectric focusing

Isoelectric focusing separates proteins in a pH gradient; each protein migrates until it reaches the pH equal to its pI, where it has no net charge and stops.