Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:1.10.3.2 (laccase)
4,656 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Binuclear cupric ion clusters have been established in: human ceruloplasmin, hemocyanin, and mushroom tyrosinase. Substantial evidence makes it very probable that fungal laccase and zucchini ascorbate oxidase contain this cluster. Some evidence makes it possible that copper clusters function in the catalytic cycles of cytochrome oxidase (mammalian) and dopamine-beta-hydroxylase. These studies throw light on the criteria which must be employed to establish the existence of functional binuclear copper clusters in enzymes: (1) Stoichiometric Criteria: binding of O2 and CO with Cu/ligand = 2; redox titrations with n = 2; (2) Physical and Chemical Criteria: magnetic evidence of diminished paramagnetism of cupric centers, EPR evidence of broadened or absent absorptions, EPR evidence of magnetic dipolar interactions among cupric ions; absorption bands characteristic of Cu(II)-Cu(II) complexes; laser resonance raman scattering characteristic of peroxidic dioxygen in the oxyforms.
...
PMID:Binuclear copper clusters as active sites for oxidases. 18 78

From the peelings of cucumber Cucumis sativus and marrow squash Cucurbita pepo var. giramontia highly purified ascorbate oxidase preparations were obtained. Molecular weights, optical and EPR spectra, total copper contents and different type copper contents of the both proteins were similar. The effects of NaN3, KCN, I- and F- on the optical and EPR spectra of the proteins were studied. The incubation of ascorbate oxidase with these anions lead to the partial reduction of the copper. The data obtained indicate that F- is bound to the copper atoms of the type 2, and that N5- modifies surroundings of these copper atoms. The copper atoms of types 1 and 2 in both ascorbate oxidases, unlike fungal laccase, are completely reduced under effect of CN-. The bleaching of ascorbate oxidase, observed in alkaline media involves also increasing of the intensity of the band at 330 nm. The results show that three types of copper in ascorbate oxidase have various sensitivities to the inorganic anions. These data are compared with results observed for another blue copper-containing enzymes, such as laccases and ceruloplasmin.
...
PMID:[Interaction of ascorbate oxidase with inorganic anions]. 58 36

The amino acid sequence of the copper-containing nitrite reductase (EC 1.7.99.3) from Achromobacter cycloclastes strain IAM 1013 has been determined by using peptides derived from digestion with Achromobacter protease I (Lys), Staphylococcus aureus V8 protease (Glu), cyanogen bromide, and BNPS-skatole in acetic acid. The subunit contains 340 amino acids. The identity of the first seven amino acids is tentative. The sequence has been instrumental in the X-ray structure determination of this molecule; in conjunction with the X-ray structure, ligands to a type I copper atom and a type II copper atom (one of each per subunit) have been identified. Comparison of the sequence to those of multi-copper oxidases such as ascorbate oxidase, laccase, and ceruloplasmin [Messerschmidt, A., & Huber, R. (1990) Eur. J. Biochem. 187, 341-352] reveals that each of two domains seen in the X-ray structure is similar to the oxidases and also to the small blue copper-containing proteins such as plastocyanin. The combination of sequence and structural similarity to ascorbate oxidase and sequence similarity to ceruloplasmin leads to a plausible model for the domain structure of ceruloplasmin.
...
PMID:Amino acid sequence of nitrite reductase: a copper protein from Achromobacter cycloclastes. 183 Feb 17

A lambda gt11 cDNA expression library was constructed from size-fractionated poly(A)-rich RNA of cultured pumpkin cells. A full-length cDNA clone for ascorbate oxidase mRNA was selected from the library by screening with synthetic oligonucleotides designed from the amino-terminal sequence of ascorbate oxidase protein. The identity of the clone was confirmed by comparing the amino acid sequence deduced by nucleotide sequence analysis with that determined for the amino-terminal sequence of pumpkin ascorbate oxidase. The nucleotide sequence of the cDNA insert was found to contain an open reading frame of 579 codons corresponding to a signal peptide of 30 amino acids and the mature 549-residue ascorbate oxidase. Furthermore, it was found that the amino acid sequence deduced from the nucleotide sequence of the cDNA insert contained four potential N-glycosylation sites and copper-binding amino acid residues located in four regions where the sequence was identical or nearly identical to those of the other known blue multicopper oxidases Neurospora crassa laccase and human ceruloplasmin.
...
PMID:Molecular cloning and nucleotide sequence of full-length cDNA for ascorbate oxidase from cultured pumpkin cells. 214 84

The present study shows that the electron spin resonance (ESR) spectral features of Rhus laccase depend considerably on the pH value of the enzyme solution and the irradiated microwave power. Because of the local protein structure change, the type 1 copper is appreciably autoreduced at alkaline pH as monitored both by the ESR and absorption spectroscopies. In addition, the ESR signal of the type 2 copper, especially its g perpendicular region, becomes prominent at alkaline pH. Protein dissociation from a water or an imidazole group coordinated to the type 2 copper is supposed to be responsible for this behavior. Besides above pH effects, the g perpendicular component of the type 2 copper ESR signal is obscured with rising microwave power level. The power saturation behavior of native laccase and its derivatives reveals that the type 2 copper is more easily saturated than the type 1 copper. Cucumis ascorbate oxidase also exhibits similar behavior upon pH variation and microwave power saturation.
...
PMID:pH and microwave power effects on the electron spin resonance spectra of Rhus vernicifera laccase and Cucumis sativus ascorbate oxidase. 215 83

On the basis of the spatial structure of ascorbate oxidase [Messerschmidt, A., Rossi, A., Ladenstein, R., Huber, R., Bolognesi, M., Gatti, G., Marchesini, A., Petruzzelli, R. & Finazzi-Agro, A. (1989) J. Mol. Biol. 206, 513-529], an alignment of the amino acid sequence of the related blue oxidases, laccase and ceruloplasmin is proposed. This strongly suggests a three-domain structure for laccase closely related to ascorbate oxidase and a six-domain structure of ceruloplasmin. These domains demonstrate homology with the small blue copper proteins. The relationships suggest that laccase, like ascorbate oxidase, has a mononuclear blue copper in domain 3 and a trinuclear copper between domain 1 and 3 and ceruloplasmin has mononuclear copper ions in domains 2, 4 and 6 and a trinuclear copper between domains 1 and 6.
...
PMID:The blue oxidases, ascorbate oxidase, laccase and ceruloplasmin. Modelling and structural relationships. 240 64

Titration of native ascorbate oxidase from green zucchini squash (Cucurbita pepo) with azide in 0.1 M-phosphate buffer, pH 6.8, exhibits a biphasic spectral behaviour. Binding of the anion with 'high affinity' (K greater than 5000 M-1) produces a broad increase of absorption in the 400-500 nm region (delta epsilon approximately 1000 M-1.cm-1) and c.d. activity in the 300-450 nm region, whereas azide binding with 'low affinity' (K approximately 100 M-1) is characterized by an intense absorption band at 420 nm (delta epsilon = 6000 M-1.cm-1), corresponding to negative c.d. activity and a decrease of absorption at 330 nm (delta epsilon = -2000 M-1.cm-1). The high-affinity binding involves a minor fraction of the protein containing Type 3 copper in the reduced state, and the spectral features of this azide adduct can be eliminated by treatment of the native enzyme with small amounts of H2O2, followed by dialysis before azide addition. As shown by e.s.r. spectroscopy, Type 2 copper is involved in both types of binding, its signal being converted into that of a species with small hyperfine splitting constant [12 mT (approximately 120 G)] in the case of the low-affinity azide adduct. The spectral similarities of the two types of azide adducts with the corresponding adducts formed by native laccase, which also exhibits Type 3 copper heterogeneity, are discussed.
...
PMID:Azide-binding studies reveal type 3 copper heterogeneity in ascorbate oxidase from the green zucchini squash (Cucurbita pepo). 284 Aug 93

cDNA clones for ascorbate oxidase were isolated from a cDNA library made from cucumber (Cucumis sativus) fruit mRNA. The library was screened with synthetic oligonucleotides that encode the NH2-terminal sequence of this enzyme. Nucleotide sequence analysis of the cloned cDNA inserts revealed a 1761-base-pair open reading frame that encoded an NH2-terminal signal peptide of 33 amino acids and a mature enzyme of 554 amino acids (Mr, 62,258). The amino acid sequence deduced from nucleotide sequence analysis agrees with the NH2-terminal amino acid sequence of the purified ascorbate oxidase, as determined by microsequencing methods. Cucumber ascorbate oxidase contained four histidine-rich regions with striking sequence homology to the corresponding parts of the other multicopper oxidases such as Neurospora crassa laccase and human ceruloplasmin and, to some extent, to a low molecular weight copper protein such as plastocyanin. Moreover, these data further support the hypothesis that the small blue copper proteins and the multicopper oxidases have evolved from the same ancestral gene. By RNA blot hybridization analysis, the mRNA for the ascorbate oxidase was found to be abundant in cucumber fruit tissue while expressed at very low levels in leaf and root tissues.
...
PMID:Primary structure of cucumber (Cucumis sativus) ascorbate oxidase deduced from cDNA sequence: homology with blue copper proteins and tissue-specific expression. 291 72

The spectroscopic features of cucumber ascorbate oxidase (AOase) and its type-2 copper-depleted (T2D) derivative, and the electron pathway among the copper sites in the enzyme have been investigated. The electronic and CD spectra of native and T2D AOase in the visible region bear a striking resemblance to those of plastocyanin or azurin, which contain type-1 copper alone. The electronic absorption shoulder of the native enzyme at around 330 nm for the native enzyme which has been assigned to type-3 copper disappears with the depletion of the type-2 copper. The reduction of AOase with a large excess of hexacyanoferrate(II) results in a selective reduction of the type-2 Cu, giving rise to an additional EPR-detectable species which is considered to be originated from partly reduced type-3 copper. The type-1 copper is, however, not reduced even in the presence of excess hexacyanoferrate(II). The redox potential of type-1 Cu was determined to be +350 mV, which is distinctly lower than that of hexacyanoferrate(II-III). Type-2 copper was supposed to be a mediator of the electron transfer between type-1 and type-3 coppers in consideration of the extremely low activity of the T2D enzyme under the same condition. A comparison of the electron pathway in AOase with that in laccase is also argued.
...
PMID:Characterization of cucumber ascorbate oxidase and its reaction with hexacyanoferrate (II). 299 89

Reoxidation process of reduced cucumber ascorbate oxidase (1.10.3.3) with dioxygen was investigated in detail through absorption, circular dichroic (CD) and electron paramagnetic resonance (EPR) spectra. One of the three type I coppers and the type II copper were reoxidized more rapidly than other type I coppers. The principal active site of ascorbate oxidase was considered to be comprised of one type I, one type II and a pair of type III coppers similarly to the active sites in laccase and ceruloplasmin. Remaining two type I and a pair of type III coppers were also disclosed to contribute to the oxidation of L-ascorbate.
...
PMID:Oxidation of reduced cucumber ascorbate oxidase. 299 19


1 2 3 4 5 Next >>

---