Copper Binding Site in Serum Amine Oxidase Treated With Sodium Diethyldithiocarbamate

Abstract

The structure of copper binding site in bovine serum amine oxidase (BSAO) treated with diethyldithiocarbamate ion(DDC) was discussed by comparing its absorption and electron spin resonance spectra with those of a model copper complex. The structure of the model complex, [Cu(2,2′-bipyridine)(DDC)]+, suggested that at least two nitrogen atoms are coordinated around the copper ion in the native BSAO. Some organic chromophore from which the pink color of BSAO stems was also observed as the difference of the absorption spectra in the region of 450 to 600 nm between BSAO-DDC and the model complex.

Reactions of bovine serum amine oxidase with NN-diethyldithiocarbamate. Selective removal of one copper ion

“…Sulphide is reported to inactivate BSAO (Dooley & Cote, 1984), but in the present procedure it only behaved as a reductant, as effective as dithionite in the Cu(II) abstraction. In agreement with the report by Suzuki et al (1982), only 10-15 % of the Cu(II) was removed when the protein was dialysed against solutions ofrecrystallized DDC in the absence of reductant. At 1.0 mM-DDC, the concentration used for Cu(II) removal, only about 50 % of the Cu(II) was able to react with BSAO, as shown by the decrease of the first hyperfine line at low field in the e.p.r.…”

“…4) identical five-line superhyperfine patterns with 1.1 mT splitting constant in the g11 region, diagnostic of two magnetically equivalent '4N nuclei, in a distorted equatorial coordination (Guzy et al, 1969;Buluggiu et al, 1972). For the DDC derivative of BSAO N2S2 co-ordination was also suggested by Suzuki et al (1982) by analogy with the spectra of a model copper complex Cu(II)-DDC-bipyridyl. In carbonic anhydrase the two nitrogen atoms were supplied by two histidine residues, and a third histidine nitrogen atom and a loosely bound water molecule were believed to occupy the axial positions (Morpurgo et al, 1983).…”

“…Nonetheless the DDC adducts of the two proteins appear to be very similar (Table 2). They display an intense absorption band, at 380 nm in BSAO and at 390 nm in carbonic anhydrase, that is assigned to a S-.Cu(II) charge transfer (Suzuki et al, 1982;Morpurgo et al, 1983). The corresponding e.p.r.…”

Effect of metal substitution on the chromophore of bovine serum amine oxidase

“…Prosthetic Groups. In previous papers (Suzuki et al, 1981(Suzuki et al, , 1982, we pointed out that there is an organic chromophore (CHR) from which the pink color of BSAO stems in BSAO. Especially, the results of the spectroscopic studies on Co-(Il)-substituted BSAO suggested that CHR displays a positive CD peak at around 370 nm and a negative CD band at ~440 nm (Suzuki et al, 1981). As represented in Figures 1, 3, and 4, native BSAO, Ni(II)BSAO, and Ni-depBSAO also have similar optical absorption and CD bands in the region 300-500 nm, clearly indicating that these bands are not concerned with metal ions but with the organic chromophore.…”

“…This enzyme exhibits the yellow-pink color which results from a broad absorption band near 480 nm. Our previous spectral studies (Suzuki et al, 1980(Suzuki et al, , 1981(Suzuki et al, , 1982 of native, Co(II) substituted, and diethyl dithiocarbamate treated BSAO have partly clarified the coordination chemistry of the copper(II) and the apparent presence of an unknown organic prosthetic group. This paper describes more profound spectroscopic and chemical properties of the chromophore, the roles of copper ion, and the intimate correlation between the two cofactors in native BSAO, and its derivatives.…”