Optimum Activity (optimum + activity)

Distribution by Scientific Domains


Selected Abstracts


PURIFICATION AND PROPERTIES OF CYCLODEXTRIN GLUCANOTRANSFERASE FROM AN ALKALOPHILIC BACILLUS sp.

JOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2004

ABSTRACT Cyclodextrin glucanotransferases (EC 2.4.1.19) (CGTase) are industrially important enzymes for production of cyclodextrin (CD) from starch. ,-CD yield of CGTase from alkalophilic Bacillus species is usually much lower than ,-CD, while from alkalophilic Bacillus sp. 7-12. ,-CD yield is close to ,-CD. A CGTase from alkalophilic Bacillus sp. 7-12 was purified and characterized. When purified by ammonium sulfate fractionation, DEAE-cellulose column chromatography and Sepharose CL-6B column chromatography, the enzyme obtained consisted of a single band that did not dissociate into subunits by SDS polyacrylamide gel electrophoresis. Molecular weight of the purified enzyme was determined to be 69,000 Da by SDS-PAGE. The enzyme showed a Kmof 1.24 mg/mL and Vmax0.101 µM/min when potato starch was used as substrate. The enzyme was stable below 70C with an optimum activity at 60C, and stable at pH range 6,10 with an optimum pH at 8.5. The enzyme activity was strongly inhibited by Ag+, Cu2+, Mg2+, Al3+, Co2+, Zn2+, Fe2+and slightly inhibited by Sn2+, Mn2+. The ions Ca2+and K+, EDTA and DTT had no influence on the enzyme activity. [source]


Insecticidal 2-hydroxy-3-alkyl-1,4-naphthoquinones: correlation of inhibition of ubiquinol cytochrome c oxidoreductase (complex III) with insecticidal activity

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 3 2002
Philip J Jewess
Abstract The insecticidal and in vitro activities of four homologous series of 2-hydroxy and acetoxy-3-substituted-1,4-naphthoquinones have been measured and correlated with their (Log) octanol/water partition coefficients (Log Ko/w). In vitro activity against mitochondrial complex III was only exhibited by 2-hydroxy-3-alkyl-1,4-naphthoquinones, indicating that the 2-acetoxy compounds act as pro-insecticides. Good correlation was observed between in vivo activity against the two-spotted spider mite, Tetranychus urticae and inhibition of complex III isolated from blowfly flight muscle. Both hydroxy and acetoxy analogues of individual compounds exhibited similar levels of in vivo activity with optimum activity for analogues with Log Ko/w values of 7,8. In contrast, the acetoxy derivatives showed superior in vivo activity against the tobacco whitefly, Bemisia tabaci. Complex III isolated from whitefly was optimally inhibited by hydroxy analogues with lower Log Ko/w values (6.0,6.5) and was also more sensitive than the blowfly enzyme to all the compounds tested. © 2002 Society of Chemical Industry [source]


Molecular cloning and characterization of OsCDase, a ceramidase enzyme from rice

THE PLANT JOURNAL, Issue 6 2008
Mickael O. Pata
Summary Sphingolipids are a structurally diverse group of molecules based on long-chain sphingoid bases that are found in animal, fungal and plant cells. In contrast to the situation in animals and yeast, much less is known about the spectrum of sphingolipid species in plants and the roles they play in mediating cellular processes. Here, we report the cloning and characterization of a plant ceramidase from rice (Oryza sativa spp. Japonica cv. Nipponbare). Sequence analysis suggests that the rice ceramidase (OsCDase) is similar to mammalian neutral ceramidases. We demonstrate that OsCDase is a bona fide ceramidase by heterologous expression in the yeast double knockout mutant ,ypc1,ydc1 that lacks the yeast ceramidases YPC1p and YDC1p. Biochemical characterization of OsCDase showed that it exhibited classical Michaelis,Menten kinetics, with optimum activity between pH 5.7 and 6.0. OsCDase activity was enhanced in the presence of Ca2+, Mg2+, Mn2+ and Zn2+, but inhibited in the presence of Fe2+. OsCDase appears to use ceramide instead of phytoceramide as a substrate. Subcellular localization showed that OsCDase is localized to the endoplasmic reticulum and Golgi, suggesting that these organelles are sites of ceramide metabolism in plants. [source]


Degradation of an Fc-fusion recombinant protein by host cell proteases: Identification of a CHO cathepsin D protease

BIOTECHNOLOGY & BIOENGINEERING, Issue 6 2009
Flavie Robert
Abstract A host-cell-related proteolytic activity was identified in a recombinant Fc-fusion protein production process. This report describes the strategy applied to characterize and isolate the enzyme responsible for this degradation by combining cell culture investigation and dedicated analytical tools. After isolation and sequencing of the clipped fragment generated in post-capture material, enzymatic activity was traced in different culture conditions, allowing identification of viable CHO cells as the source of protease. Inhibitors and pH screenings showed that the enzyme belongs to an aspartic protease family and is preferably active at acidic pH. The protease was isolated by purification on a pepstatin A column and characterized as a protein related to cathepsin D. An additional metallo-protease inhibited by EDTA was identified with an optimum activity at neutral pH. This study is an example of how quality and stability of therapeutic recombinant molecules are strongly influenced by cell culture parameters. Biotechnol. Bioeng. 2009; 104: 1132,1141. © 2009 Wiley Periodicals, Inc. [source]