Search results for "ENZYMES"
showing 10 items of 730 documents
Common genetic denominators for Ca++-based skeleton in Metazoa: role of osteoclast-stimulating factor and of carbonic anhydrase in a calcareous spong…
2012
Calcium-based matrices serve predominantly as inorganic, hard skeletal systems in Metazoa from calcareous sponges [phylum Porifera; class Calcarea] to proto- and deuterostomian multicellular animals. The calcareous sponges form their skeletal elements, the spicules, from amorphous calcium carbonate (ACC). Treatment of spicules from Sycon raphanus with sodium hypochlorite (NaOCl) results in the disintegration of the ACC in those skeletal elements. Until now a distinct protein/enzyme involved in ACC metabolism could not been identified in those animals. We applied the technique of phage display combinatorial libraries to identify oligopeptides that bind to NaOCl-treated spicules: those oligop…
Electrochemical synthesis of coenzymes Qn by oxidation of tetramethoxy precursors
2009
The electrochemical oxidation of tetramethoxy precursors (2) to coenzymes Q (n) (1) at a carbon anode was investigated both in a bench-scale batch electrochemical reactor and in a continuous recirculation reaction system equipped with a parallel-plate electrochemical divided cell. High faradic efficiency (> 60%) and excellent selectivity (> 90%) in coenzymes Q (n) were obtained in CH3CN or CH3CN/CH2Cl2 + 0.15 M Bu4NBF4 under potentiostatic or amperostatic alimentation.
Enzymatic Activity of CD26 (Dipeptidylpeptidase IV) is not Required for Its Signalling Function in T Cells
1993
Abstract CD26 is a proteolytic enzyme (dipeptidylpeptidase IV) expressed on the T cell surface that defines an alternative activation signal for human T lymphocytes. Crosslinking of CD26 via monoclonal antibodies triggers proliferation and cytotoxicity in preactivated T cells. In this study, we used highly specific competitive and irreversible inhibitors of dipeptidylpeptidase IV to study the role of the enzymatic activity in activation of CD26- transfected T cells as well as of CD26-expressing normal human T cell clones. These inhibitors at concentrations that blocked up to 95% of the enzymatic activity, did not specifically inhibit T cell activation neither via TCR/CD3 nor via CD26 itself…
Phytochemical profile and antioxidative properties of Plinia trunciflora fruits: A new source of nutraceuticals.
2020
Abstract This study evaluated the polyphenol profile and the antioxidative properties of Plinia trunciflora (O. Berg) Kausel fruits. Folin-Ciocalteau and pH-jumping methods indicated that these berries are a major source of antioxidant polyphenols (1201.05 mg GAE/100 g FW), particularly anthocyanins. HPLC-DAD-ESI-MS/MS analysis identified cyanidine glycosides as the main components. Flavon-3-ols and hydrolysable-tannins were also found. CAA assay showed that extracts of P. trunciflora fruits prevent lipid peroxidation in HepG2 cells with higher efficacy than other colourful fruits (CAA50 935.25 mg FW/mL cell medium). Moreover, our results suggested that the observed antioxidant protection i…
Almond (Prunus dulcis cv. Casteltermini) Skin Confectionery By-Products: New Opportunity for the Development of a Functional Blackberry (Rubus ulmifo…
2021
This work proposes for the first time a model for reusing almond (Prunus dulcis cv. Casteltermini from Sicily, Southern Italy) skin to formulate a new functional blackberry (Rubus ulmifolius Schott) jam. For this purpose, blackberries were analysed fresh and as jam, traditionally prepared with a minimum fruit amount of 80%. Different percentages of almond skin (20, 15, and 10% w/w) were added to jam. The phytochemical profile of enriched jam was investigated by LC-ESI/LTQOrbitrap/MS analyses. Anthocyanins, hydrolysable tannins, and triterpenoids were identified in a blackberry extract, while proanthocyanidins, flavonoids, and oxylipins were identified in an almond extract. The n-hexane extr…
Effect of antibodies against cytochrome P-450 on demethylation and denitrosation of N-nitrosodimethylamine and N-nitrosomethylaniline.
1988
Rat liver microsomes which were induced either with ethanol or PB were incubated with NDMA or NMA. Formaldehyde generation and nitrite formation were measured as metabolic parameters for oxidative bioactivation and denitrosation, respectively. The influence of antiserum PB3a1 and PB22 containing antibodies against the corresponding cytochrome P-450 species on both metabolic functions was investigated. The results showed that the influence on formaldehyde production and denitrosation varied independently in that both parameters were either not affected, or influenced in an opposite way, or inhibited to a different degree. Especially remarkable was the 80% inhibition of formaldehyde generatio…
Glutamine synthetases of green and etiolated leaves ofSinapis alba : Evidence of the identity of the respective enzyme proteins.
1989
Studies on the glutamine synthetases (GS, EC 6.3.1.2) of green (GS2) and etiolated leaves (GSet) ofSinapis alba L. (cv. Steinacher) revealed striking similarities between the respective enzyme proteins. The enzymes showed corresponding chromatographic properties, both on dimethylaminoethyl-Sephacel and on hydroxylapatite columns. The purified GS proteins were also identical with regard to the molecular weight of their subunits. Isoelectrofocusing of pure GSet yielded two distinct polypeptide bands in the pH 5.6 region of the gels. This pattern corresponded to the two strong bands of GS2. Two charge variants of GS polypeptides could be detected by Western-blot analysis of the soluble protein…
Involvement of acyl coenzyme A oxidase isozymes in biotransformation of methyl ricinoleate into gamma-decalactone by Yarrowia lipolytica.
2000
ABSTRACT We reported previously on the function of acyl coenzyme A (acyl-CoA) oxidase isozymes in the yeast Yarrowia lipolytica by investigating strains disrupted in one or several acyl-CoA oxidase-encoding genes ( POX1 through POX5 ) (H. Wang et al., J. Bacteriol. 181:5140–5148, 1999). Here, these mutants were studied for lactone production. Monodisrupted strains produced similar levels of lactone as the wild-type strain (50 mg/liter) except for Δ pox3 , which produced 220 mg of γ-decalactone per liter after 24 h. The Δ pox2 Δpox3 double-disrupted strain, although slightly affected in growth, produced about 150 mg of lactone per liter, indicating that Aox2p was not essential for the biotra…
A simple model for barrier frequencies for enzymatic reactions.
2010
We present a simple model to rationalize the effects of environment on the reaction barrier frequencies derived from free energy profiles. These frequencies are relevant in deviations of a rate constant from its transition state theory value and in determining which environmental dynamics participate in the reaction. In particular, this simple model can be used to understand the changes in the reaction barrier frequencies of an enzymatic catalyzed reaction and the corresponding uncatalyzed process in aqueous solution, a change which has implications for dynamical environmental effects on the enzymatic reaction. Two possible cases are analyzed, in which the polarity (charge separation/locali…
Molecular and Functional Characterisation of Hemocyanin of the Giant African Millipede Archispirostreptus gigas
2013
SummaryIn contrast to other terrestrial arthropods where gaseous O2 that fuels aerobic metabolism diffuses to the tissues in tracheal tubes, and most other metazoans where O2 is transported to tissues by circulating respiratory proteins, the myriapods (millipedes and centipedes) strikingly have tracheal systems as well as circulating hemocyanin (Hc). In order to elucidate the evolutionary origin and biological significance of millipede Hc we report the molecular structure (subunit composition and amino acid sequence) of multimeric (36-mer) Hc from the forest-floor dwelling giant African millipede Archispirostreptus gigas and its allosteric oxygen binding properties under various physico-che…