Active transport of pyridoxine, pyridoxal, and pyridoxamine occurs in resting cells of Saccharomyces carlsbergensis 4228 and can lead to intracellular concentrations of free vitamin much higher than those supplied externally. The initial Km for pyridoxine uptake is 3.6 x 10(-7) M at 30 degrees and pH 4.5, which are optimum for growth. Transport is inhibited by many unphosphorylated vitamin anal...

A major obstacle to using widely available and low-cost lignocellulosic feedstocks to produce renewable fuels and chemicals is the high cost and low efficiency of the enzyme mixtures used to hydrolyze cellulose to fermentable sugars. One possible solution entails engineering current cellulases to function efficiently at elevated temperatures in order to boost reaction rates and exploit several ...

AIM This study aims to produce and assay cellulolytic enzyme activity (endo-(1,4)-β-D-glucanase, exo-(1,4)-β-D-glucanase, and β-glucosidase, at optimum temperature and optimum pH) of Enterobacter cloacae WPL 214 isolated from bovine rumen fluid waste of Surabaya Abbatoir, Indonesia. MATERIALS AND METHODS To produce enzyme from a single colony of E. cloacae WPL 214, 98 × 10(10) CFU/ml of isola...

Four different double-compression CO2 transcritical refrigeration cycles are studied: double-compression external intercooler cycle (DCEI), double-compression external intercooler cycle with an expander (DCEIE), double-compression flash intercooler cycle (DCFI), double-compression flash intercooler cycle with an expander (DCFIE). The results showed that the optimum gas cooler pressure and optim...

Alternating current threshold excitation of space-clamped squid giant axons was measured as a function of frequency, external calcium concentration, temperature (from 10 degrees to 35 degrees C), and hyper- and depolarizing steps. In normal axons there is usually an optimum frequency at about 120 Hz, at which the threshold is a minimum. The threshold rises at both lower and higher frequencies t...

Glutamine synthetase of roots, etiolated cotyledons and green leaves from mustard plants cannot all clearly be separated by DEAE-Sephacel chromatography. However, the enzyme of the roots, etiolated cotyledons and green leaves, respectively, differed in the kinetic properties deter­ mined in the crude extract. The root enzyme showed a pH-optimum of about 6.9, a Km value of 3 m M for glutamate an...

In this study, urease was isolated from Cicer arietinum and immobilized in calcium alginate beads. Various parameters, such as effect of thermal stability, temperature, optimum pH and pH stability, substrate concentration, reuse and storage stability were investigated and the results of the investigation were compared with the soluble enzyme. The activity yield of immobilization was calculated ...

The metagenomes of uncultured microbial communities are rich sources for novel biocatalysts. In this study, esterase EstA3 was derived from a drinking water metagenome, and esterase EstCE1 was derived from a soil metagenome. Both esterases are approximately 380 amino acids in size and show similarity to beta-lactamases, indicating that they belong to family VIII of the lipases/esterases. EstA3 ...

Starch phosphorylase has been isolated from cabbage (Elephantopus scabar) leaves and partially purified using ammonium sulfate fractionation. The partially purified enzyme was desalted using SephadexG-25 chromatography. In the direction of polysaccharide synthesis, the enzyme showed optimum activity at pH 6.0 with two half pH optima at pH 5.3 and pH 7.1 whereas in the direction of glucose-1-pho...

The storage of gases in porous adsorbents, such as activated carbon and carbon nanotubes, is examined here thermodynamically from a systems viewpoint, considering the entire adsorption-desorption cycle. The results provide concrete objective criteria to guide the search for the "Holy Grail" adsorbent, for which the adsorptive delivery is maximized. It is shown that, for ambient temperature stor...