Some properties of active and latent catechol oxidase of mushroom

Latent form of mushroom catechol oxidase was activated by O,1% sodium dodecyl sulfate (SDS). Catalytic power of the latent form, calculated from the kinetic parameters was 1,8 times higher than that of active one. Salicyl hydroxamic acid (SHAM) appeared as a powerful inhibitor for both active and latent forms of catechol oxidase. However, in the range of 150-250 μM SHAM the inhibitory effect for active catechol oxidase was significantly higher than that for the latent one. Non-competitive and irreversible characteristics of inhibition of latent and active catechol oxidase was calculated from kinetic data. Electrophoretic analysis followed by scanning of the gels was used. The spots' absorbance was determined from a computer image of the isoenzyme band patterns. It allowed us to estimate gels quantitatively. Presence of one additional clearly defined slow moving isoform of SDS-activated catechol oxidase, differed in the respect of 3 bands for the active and 4 bands for the total.

Σύμπλοκα του Cu(II) και Mn(II) με φαινοξυαλκανοϊκά οξέα και μεταλλοκορονοειδείς ενώσεις του Ni(II)

Complexes of Mn(II) and Cu(II) with phenoxyalkanoic herbicides as ligands as wellas metallacrowns of Ni(II) hosting herbicides were prepared and characterized. The herbicidesligands L 2,4-DP, MCPA, 2,4,5-T, 2,4-D and 2,3-D have the characteristic existence of thecarboxylato group. All complexes were characterized spectroscopically (IR, UV-Vis, EPR),analytically and magnetically.Mn(II) complexes have the general type [Mn(L)2(H2O)2]n. In these complexes, thecarboxylate group of the ligands is coordinated in a bidentate bridging mode. The crystalstructure of the 2-dimensioned complex [Mn(MCPA)2(H2O)2]n was determined with X-Ray.This complex shows weak antiferromagnetic behavior.Cu(II) complexes have the general types Cu(L)2(MeOH)2 or Cu2(L)4(MeOH)2,Cu(L)2(L')(H2O), [Cu(L)(L')2]Cl and Cu2(L)4(bipyam)2, where L': a heterocyclic N-donorligand (bipy, phen, bipyam). In complex Cu2(2,3-D)4(MeOH)2, the carboxylate group of theligand 2,3-D is coordinated in a bidentate bridging mode, in complexes of the general typeCu(L)2(L')(H2O) and [Cu(L)(L')2]Cl the carboxylate group is in a monodentate mode, while indinuclear complexes of the type Cu2(L)4(bipyam)2 both monodentate mode and bidentatebridging mode for the carboxylate group were found. In all complexes Cu+2 ion is five coordinatedand could be described as having highly distorted square pyramidal to trigonalbipyramidal geometry. The neutral mononuclear complexes of the type Cu(L)2(L’)(H2O)exhibit magnetochemical properties which are characteristic of a di- or multi-nuclear structureand are due to intra- and inter-molecular hydrogen bonds. Antimicrobial studies of thecomplexes showed that the best inhibition is provided by the cationic mononuclear complexesof the type [Cu(L)(L')2]Cl.Ni(II) metallacrowns hosting herbicides are of the general type NiII2(L)2(CH3OH)3(H2O)[12-MCNi(II)N(shi)2(pko)2-4][12-MCNi(II)N(shi)3(pko)-4], where H3shi=salicyl-hydroxamic acidand Hpko=di-(2-pyridyl)-ketonoxim, and are consisted of two metallacrown rings with +1 and-1 charges. Both metallacrown rings have an encapsulated Ni(II) ion and are held togetherthrough Ni-O bonds. Magnetic measurements for complex NiII2(MCPA)2[12-MCNi(II)N(shi)2(pko)2-4][12-MCNi(II)N(shi)3(pko)-4](CH3OH)3(H2O) showed weak antiferromagneticbehavior.

ISOLATION AND CHARACTERIZATION OF TEMPERATURE-SENSITIVE RESPIRATORY MUTANTS OF NEUROSPORA CRASSA

ABSTRACT Filtration-enrichment and inositol-less death methods of mutant isolation, coupled with a screen for cyanide-insensitive respiration, proved to be highly efficient methods for isolating temperature-sensitive (ts) nuclear Neurospora mutants having defective respiration. Eighteen different ts respiratory mutants have been isolated. Most of them are pleiotropic and defective in one or more of the following phenotypes: cytochrome aa3, b, and c (individual or multiple defects); oligomycin inhibition of ATPase activity; respiration and its inhibition by KCN and salicyl hydroxamic acid; and growth rates in liquid and solid media at 25° and 38°. Among these mutants are the first cytochrome c mutant of Neurospora and an extranuclear ts ATPase mutant. An added bonus was the fact that aver half of the mutants were affected either in ribosome assembly or in protein synthesis in the mitochondrion. We have yet to find any mutants completely lacking activities associated with the respiratory chain. However, the wide spectrum of mutants isolated here, along with those currently available, constitutes a considerable resource for investigating respiration in obligate aerobes.