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Alkaline transition of phytocyanins: a comparison of stellacyanin and umecyanin.

Alkaline transition of phytocyanins: a comparison of stellacyanin and umecyanin.

Authors :
Dennison C
Harrison MD
Lawler AT
Source :
The Biochemical journal [Biochem J] 2003 Apr 15; Vol. 371 (Pt 2), pp. 377-83.
Publication Year :
2003

Abstract

The effect of pH on Cu(I) and Cu(II) forms of the isolated soluble domain of the stellacyanin from Rhus vernicifera (SCu), the Japanese lacquer tree, has been studied by electronic and NMR spectroscopy and using direct electrochemical measurements. A pK(a) value of 10.1-10.4 is observed for the alkaline transition in this oxidized phytocyanin and results in a slightly altered active-site structure, as indicated by changes in the visible and paramagnetic (1)H NMR spectra. Electrochemical studies show that the pK(a) value for this transition in SCu(I) (reduced SCu) is 11.0. These results are compared with those recently obtained for other phytocyanins, and in particular umecyanin. In all cases, the alkaline transition is caused by the deprotonation of the surface lysine residue adjacent to the axial ligand. This lysine residue is completely conserved in known phytocyanin sequences. Also highlighted in these studies are the remarkable active-site similarities between stellacyanin and umecyanin.

Details

Language :
English
ISSN :
0264-6021
Volume :
371
Issue :
Pt 2
Database :
MEDLINE
Journal :
The Biochemical journal
Publication Type :
Academic Journal
Accession number :
12529171
Full Text :
https://doi.org/10.1042/BJ20021869