Open AccessKinetics of the Interaction between Ceruloplasmin and Reducing Substrates
Author(s) -
Gunnarsson PerOlov,
Nylén Ulf,
Pettersson Gösta
Publication year - 1973
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1973.tb02954.x
Subject(s) - ceruloplasmin , chromophore , reaction rate constant , chemistry , kinetics , substrate (aquarium) , photochemistry , analytical chemistry (journal) , chromatography , biochemistry , physics , oceanography , quantum mechanics , geology
Decolourization of the 610‐nm chromophore of ceruloplasmin by ascorbate is due to a ratedetermining second‐order interaction between enzyme and substrate. Apparent rate constants for this process appear to be independent of the oxidation state of the 340‐nm chromophore of the protein, and decrease with pH over the range pH 5–7. Second‐order rate constants for the reduction of ceruloplasmin by various substrates are linearly correlated to the reciprocal value of the corresponding K m ‐values, and agree in magnitude with the steady‐state kinetic quotient V/K m . This means that differences in the rate of oxidation of various substrates can be mainly attributed to differences in the rate of reduction of the 610‐nm chromophore and correlated to differences in the ionization potential of the reducing substrates.