22 research outputs found
Isolation and Characterization of EstC, a New Cold-Active Esterase from Streptomyces coelicolor A3(2)
The genome sequence of Streptomyces coelicolor A3(2) contains more than 50 genes coding for putative lipolytic enzymes. Many studies have shown the capacity of this actinomycete to store important reserves of intracellular triacylglycerols in nutrient depletion situations. In the present study, we used genome mining of S. coelicolor to identify genes coding for putative, non-secreted esterases/lipases. Two genes were cloned and successfully overexpressed in E. coli as His-tagged fusion proteins. One of the recombinant enzymes, EstC, showed interesting cold-active esterase activity with a strong potential for the production of valuable esters. The purified enzyme displayed optimal activity at 35°C and was cold-active with retention of 25% relative activity at 10°C. Its optimal pH was 8.5–9 but the enzyme kept more than 75% of its maximal activity between pH 7.5 and 10. EstC also showed remarkable tolerance over a wide range of pH values, retaining almost full residual activity between pH 6–11. The enzyme was active toward short-chain p-nitrophenyl esters (C2–C12), displaying optimal activity with the valerate (C5) ester (kcat/Km = 737±77 s−1 mM−1). The enzyme was also very active toward short chain triglycerides such as triacetin (C2:0) and tributyrin (C4:0), in addition to showing good primary alcohol and organic solvent tolerance, suggesting it could function as an interesting candidate for organic synthesis of short-chain esters such as flavors
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Measurement of the branching fraction ratios and CP asymmetries in B-→ D0 CP K-decays
We present a preliminary study of and decays, with the reconstructed in the CP-odd
eigenstates , , in the CP-even eigenstates ,
, and in the (non-CP) flavor eigenstate . Using a
sample of about 382 million Y(4S) decays into BBbar pairs, collected with the
BABAR detector operating at the PEP-II asymmetric-energy B Factory at SLAC, we
measure the ratios of the branching fractions R_CP+- and the direct CP
asymmetries A_CP+-. The results are:
R_CP- = 0.81 \pm 0.10 (stat) \pm 0.05 (syst)
R_CP+ = 1.07 \pm 0.10 (stat) \pm 0.04 (syst)
A_CP- = -0.19 \pm 0.12 (stat) \pm 0.02 (syst)
A_CP+ = 0.35 \pm 0.09 (stat) \pm 0.05 (syst
Detecting conservation benefits in spatially protected fish populations with meta-analysis of long-term monitoring data
Marine protected areas (MPA) produce a
positive effect on fish populations, but this may be difficult
to identify due to the high temporal variability of
populations. Meta-analysis is an option for analysing
data from different sources and sampling designs and it
can address problems related to temporal and spatial
variability in fish populations. We analysed fish abundance
data from visual counts conducted in summer,
from 1996 to 2002, in the MPA of Tabarca (Alicante,
Spain). The results showed an overall positive effect of
protection at the species and family levels. Overall
abundance of fishes inside the reserve was, on average,
1.22 times higher than outside the reserve boundaries.
Positive effect of protection was found for Boops
boops, Diplodus annularis, Diplodus cervinus, Epinephelus
marginatus, Epinephelus costae and Epinephelus
aenus. Species of Labrids were not affected by
protection, except for Thalassoma pavo and Symphodus
ocellatus. Meta-analysis of temporal data allows
evaluation of the protection MPA provide and is particularly
useful when data sources have different experimental
designs or sampling programs. The Tabarca
MPA has benefited fish populations by increasing their
abundance and we suggest that meta-analysis is a complementary
tool for the management of MPAs