The subsequent effect of interaction between Co(2+) and human serum albumin or bovine serum albumin.
A notable hysteretic effect has been observed in the interaction of Co(II) with human serum albumin (HSA) or bovine serum albumin (BSA) using UV-Visible spectrometry at physiological pH (7.43), which shows that the binding between Co(II) and HSA or BSA may induce a slow transition of HSA or BSA from the conformation of weaker affinity for Co(II) to one of stronger affinity (A-B transition). The rate constants and activation parameters of this transition were measured and are discussed. It is inferred that such a conformation transition may occur due to the binding of the first Co(II) ion with the peptide segment of N-terminal residues 1-3, which results in a 'hinged movement' of the relatively hydrophobic 'valley' in the IA subdomain. This process leads to a slow conformational transition in the albumins, makes the other binding sites of Co(II) exposed, and shows a positive cooperativity effect. The LMCT (ligand-to-metal charge transition) bands of the Co(II)-HSA and Co(II)-BSA systems also show a kind of hypochromic effect featuring a dipole-dipole interaction mechanism. This phenomenon is rarely reported.
Liang
H
H
Department of Chemistry, Guangxi Normal University, Guilin 541004, PR China. bioinorganicchem@263.net
Huang
J
J
Tu
C Q
CQ
Zhang
M
M
Zhou
Y Q
YQ
Shen
P W
PW
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003035:Cobalt / Q000737:chemistry* / Q000378:metabolism; D004347:Drug Interactions; D006801:Humans; D007700:Kinetics; D008024:Ligands; D008968:Molecular Conformation; D012709:Serum Albumin / Q000737:chemistry* / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism; D013057:Spectrum Analysis
D008024:Ligands; D012709:Serum Albumin; D012710:Serum Albumin, Bovine; D003035:Cobalt