EurekaMag.com logo
+ Site Statistics
References:
53,214,146
Abstracts:
29,074,682
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Proton and oxygen 17 magnetic resonance relaxation in rhus vernicifera laccase ec 1.10.3.2 solutions proton exchange with type 2 copper ii ligands



Proton and oxygen 17 magnetic resonance relaxation in rhus vernicifera laccase ec 1.10.3.2 solutions proton exchange with type 2 copper ii ligands



Biochemistry 19(23): 5181-5189



Longitudinal (T1-1) and transverse (T2-1) NMR relaxation rates of 1H and 17O of water molecules were measured in solutions of oxidized R. vernicifera laccase to investigate the structural and dynamic aspects of water coordination to its type 2 Cu(II) site. The magnitude and negative temperature dependence of the paramagnetically induced proton T1-1 and T2-1 showed that the proton fast-exchange mechanism is operative. The field dependence of T1,pmg-1 gave an apparent correlation time of 2.7 ns for the 9-60 MHz range. T1,pmg-1 is pH dependent, giving 2 dissociation steps with pK = 6.2 and 8.6 which are attributed to the hydrolysis of a H2O molecule and a protein hydroxyl group coordinated to the type 2 Cu(II), respectively. Relaxation rates of 17O were not paramagnetically enhanced. Neither T1-1 nor T2-1 values of both 1H and 17O were significantly affected by the binding of fluoride or azide ions to type 2 Cu(II). The water oxygen equatorially bound to type 2 copper does not exchange on the NMR time scale. The paramagnetic relaxation via the fast exchange mechanism originates from proton transfer between the Cu(II)-bound water molecule or hydroxyl group and the buffered solution, acid-base catalyzed by a protein residue. The relative inertness of the water oxygen is consistent with the structural concept of a cavity which accommodates the laccase type 2 (and type 3) copper sites, the active centers involved in O2 reduction, and is connected to the bulk solvent via an orifice which in the native oxidized enzyme is only penetrable by protons. A tentative model of the type 2 Cu coordination structure is presented.

(PDF 0-2 workdays service: $29.90)

Accession: 006215376

Download citation: RISBibTeXText



Related references

Proton and oxygen-17 magnetic resonance relaxation in Rhus laccase solutions: proton exchange with type 2 copper(II) ligands. Biochemistry 19(23): 5181-5189, 1980

The proton nmr relaxation of rhus vernicifera laccase assignment to different types of copper. Biochemical & Biophysical Research Communications 111(3): 824-829, 1983

Electron nuclear double resonance spectra of the type 1 copper center in japanese lacquer tree rhus vernicifera laccase and type 2 copper depleted laccase. Biochimica et Biophysica Acta 831(1): 8-12, 1985

Electron nuclear double resonance spectra of the type 1 copper centre in Japanese lacquer tree (Rhus vernicifera) laccase, and type 2 copper-depleted laccase. Biochimica et biophysica acta: protein structure and molecular enzymology0, 831(1): 8-12, 1985

Low-temperature resonance-Raman spectra of Japanese-lacquer-tree (Rhus vernicifera) laccase, type-2-copper-depleted laccase and H2O2 hydrogen peroxide-treated type-2-copper-depleted laccase. Biochemical journal Molecular aspects including rapid papers 213(2): 503-506, 1983

Low temperature resonance raman spectra of japanese lacquer tree rhus vernicifera laccase type 2 copper depleted laccase and hydrogen per oxide treated type 2 copper depleted laccase. Biochemical Journal 213(2): 503-506, 1983

Low-temperature resonance-Raman spectra of Japanese-lacquer-tree (Rhus vernicifera) laccase, type-2-copper-depleted laccase and H2O2-treated type-2-copper-depleted laccase. Biochemical Journal 213(2): 503-506, 1983

Susceptibility studies of laccase ec 11032 and oxy hemo cyanin using an ultra sensitive magnetometer anti ferro magnetic behavior of the type 3 copper in rhus vernicifera laccase. 1976

Effects of laser radiation on rhus vernicifera laccase type 2 copper depleted laccase and stellacyanin. Journal of Inorganic Biochemistry 20(1): 87-92, 1984

X ray absorption edge determination of the oxidation state and coordination number of copper application to the type 3 site in rhus vernicifera laccase and its reaction with oxygen. Journal of the American Chemical Society 109(21): 6433-6442, 1987

The removal of the type-2 copper from Rhus vernicifera laccase. Biochimica et Biophysica Acta 1160(3): 239-245, 1992

X ray absorption study of rhus vernicifera laccase evidence for a copper copper interaction which disappears on type 2 copper removal. Biochemistry 23(15): 3428-3434, 1984

Selective removal of type 2 copper from Rhus vernicifera laccase. Febs Letters 70(1): 87-90, 1976