Hydroxyproline stabilizes the collagen triple helix through hydrogen bonding.
pI = (2.34 + 9.60)/2 = 5.97.
Myoglobin has a high oxygen affinity and releases oxygen only at low oxygen tension.
Substrate binding induces conformational changes that optimize catalysis.
β-turns reverse the direction of the polypeptide chain and are stabilized by hydrogen bonding.
Oxygen binding at one site increases affinity at other sites through conformational change.
Glycine's small side chain allows conformations inaccessible to other amino acids.
Low pH and high CO₂ reduce oxygen affinity, promoting oxygen delivery.
Branched β-carbon side chains create steric hindrance in α-helices.
Most φ and ψ angle combinations are sterically forbidden for amino acids other than glycine.
Heat disrupts weak interactions but usually leaves the covalent peptide backbone intact.
Chaperones bind exposed hydrophobic regions of unfolded proteins, preventing aggregation and promoting correct folding.
Histidine's pKa is close to physiological pH, making it ideal for acid-base catalysis.
β-sheets are classified according to the orientation of adjacent strands.
The heme prosthetic group contains Fe²⁺, which reversibly binds oxygen.
Protein function depends on proper folding into the native three-dimensional structure.
The oxidizing environment of the endoplasmic reticulum promotes the formation of disulfide bonds in secreted and membrane proteins.
The Val-6 substitution creates a hydrophobic patch on deoxyhemoglobin, leading to polymerization and sickling of red blood cells.
Domains are independently folded regions within a single polypeptide and are part of tertiary structure.
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