Ligand binding equilibrium and kinetic measurements on the dimeric myoglobin of Busycon canaliculatum and the comparative ligand binding of diverse non-cooperative heme proteins.
The rate constants and delta H degrees for the non-cooperative dimeric Busycon myoglobin are: oxygen, k' = 4.75 X 10(7) M-1 sec-1, k = 71 sec-1, and CO, l'= 3.46 X 10(5) M-1 sec-1, l = 0.0052 sec-1 at 20 degrees C, pH 7, delta H degrees = -3 kcal/mol for O2 and CO.2. Log-log plots of k vs K for oxygen and of l' vs L for CO binding for numerous non-cooperative hemoglobins and myoglobins point to a large steric influence of the protein on heme ligation reactions. Many of the proteins behave as "R" state for one ligand, but "T" for the other.
D000818:Animals; D002248:Carbon Monoxide / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D006420:Hemeproteins / Q000378:metabolism*; D007700:Kinetics; D008024:Ligands; D008974:Mollusca / Q000378:metabolism*; D009211:Myoglobin / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism
D006420:Hemeproteins; D008024:Ligands; D009211:Myoglobin; D002248:Carbon Monoxide; D010100:Oxygen