Optical properties of japanese-lacquer-tree (Rhus vernicifera) laccase depleted of type 2 copper(II). Involvement of type-2 copper(II) in the 330nm chromophore.

1. Spectroscopic and functional properties of Japanese-lacquer-tree (Rhus vernicifera) laccase were re-investigated, with special emphasis on the relationships between the different types of copper centres (Types 1, 2, and 3). 2.

Role of oxygen radicals scavenging enzymes in the protoporphyrin induced photohemolysis.

Inhibition of superoxide dismutase by diethyldithiocarbamate or cyanide increases the rate of red blood cells lysis after irradiation in the presence of protoporphyrin IX. Catalase activity, which is decreased during the photohemolytic process, appears to be not essential for the lytic event. No relationship between catalase activity and hemolysis rate was found.

Inhibition of diamine oxidase by antihistaminic agents and related drugs.

Various drugs were tested as inhibitors of diamine oxidase on the basis of chemical relationships to the enzyme substrates. It was found that serotonine tryptamine and phenformin are good competitive inhibitors while cimetidine and pheniprazine are non-competitive inhibitors. Other antihistaminic drugs like promethazine are less powerful inhibitors.

Selective inactivation of catalase during protoporphyrin induced photohemolysis of human red blood cells.

The level of some enzymatic activities in red blood cells before and after photohemolysis induced by protoporphyrin IX was studied. A 30% decrease in catalase activity was found both in normal erythrocytes and those from patients affected by favism. Other proteins though present in larger amounts inside the erythrocytes are not affected by the photohemolytic process.

Differential denaturation of a crystalline Bence-Jones type cryoprotein as monitored by fluorescence.

1) A Bence-Jones type protein (Cryo-Ver) showing the cold precipitation phenomenon has an extremely low intrinsic fluorescence when excited at 280-295 nm. 2) This fluorescence increases considerably upon denaturation of the molecule by heat or guanidine hydrochloride. Guanidine is about twice as effective as heat in terms of fluorescence yield.

The fine structure of luminescence spectra of azurin.

The spectra of azurin absorption, fluorescence, phosphorescence and fluorescence excitation have been measured in aqueous solutions at ordinary and liquid nitrogen temperatures. The fluorescence spectra of azurin even at ordinary temperatures have a well resolved fine vibrational structure. The frequency analysis reveals practically the same wave number distances between the main structure peaks in fluorescence spectra at room and low temperatures and in phosphorescence spectra.

Anion complexes of Cu(II) and Co(II) bovine carbonic anhydrase as models for the copper site of blue copper proteins.

1. The presence of two intense transitions in the optical absorption spectrum of the sulfide and 2-mercaptoethanol complexes of Cu(II) and Co(II)-substituted bovine carbonic anhydrase suggest that charge-transfer interactions between sulfur and an acceptor group of the protein play an important role in the stabilization of these complexes. 2.

Labile sulfur in human Superoxide dismutase.

1. The nautre of the intense absorption band at 320 nm of the copper and zinc-containing enzyme superoxide dismutase, from human red blood cells, has been investigated. The band does not depend on the metal prosthetic groups of the enzyme, as it is still present in the apo protein.

Changes in the fluorescence and absorbance of lipoxygenase-1 induced by 13-Ls-hydroperoxylinoleic acid and linoleic acid.

1. The addition of 13-Ls-hydroperoxylinoleic acid to lipoxygenase-1 (linoleate: oxygen oxidoreductase EC 1.13.

Selenium binding to beef-kidney rhodanese.

The reaction of beef kidney rhodanese with selenosulfate was studied. The selenium-treated enzyme shows an absorption spectrum with a maximum at 375 nm attributable to a sulfoselenide group. This absorption is bleached by addition of cyanide.

The effect of azide on the spectral and catalytic properties of ascorbate oxidase.

(1) 45% of the total copper of green zucchini ascorbate oxidase is EPR-detectable. At least two species of copper are present, one with a small A parallel (Type 1) and one with a large A parallel (Type 2). Computer simulated spectra indicated 50% contribution by each type of copper.