in haemoglobin the allosteric regulators all weaken oxygen affinity
in a tissue the partial pressure of oxygen is 26.5 Torr. If the pH falls with no change in the partial pressure of oxygen, more oxygen will be released from Hb
true because as the pH falls that's a signal that oxygen is being used and so more is needed
enzymes decrease the activation energy
enzymes do not change the total free energy change of a reaction
the distal histidine:
decreases the strength of binding of carbon monoxide
is at the side of the haem group where oxygen binds
sterically blocks the formation of haem-O2-haem sandwiches
the a1b1 subunits rotate by 15 degrees with respect to the a2b2 subunits
deoxyhaemoglobin is in the tense state
oxyhaemoglobin is in the relaxed state
oxygen:
concentration is typically expressed as pO2
concentration is 155 mmHg in the air we breathe
is transported from the lungs to cells by haemoglobin
concentration can be 1 mmHg inside cells
enzymes increase reaction rates
retinol-binding protein:
holds the hydrophobic retinol residues in a hydrophobic pocket
binds 1 molecules of retinol
is synthesised in the liver
is itself bound to a larger protein, transthyretin
in haemoglobin-oxygen binding the pO2 of 26.6 mmHg
represents the Kd and the p50
represents the oxygen concentration at which 50% of sites are filled
