Abstract:
:The effect of trehalose (0.5 M) on the thermal stability of cutinase in the alkaline pH range was studied. The thermal unfolding induced by increasing temperature was analyzed in the absence and in the presence of trehalose according to a two-state model (which assumes that only the folded and unfolded states of cutinase were present). Trehalose delays the reversible unfolding. The midpoint temperature of the unfolding transition (Tm) increases by 4.0 degrees C and 2. 6 degrees C at pH 9.2 and 10.5, respectively, in the presence of trehalose. At pH 9.2 the thermal unfolding occurs at higher temperatures (Tm is 52.6 degrees C compared to 42.0 degrees C at pH 10.5) and a refolding yield of around 80% was obtained upon cooling. This pH value was chosen to study the irreversible inactivation (long-term stability) of cutinase. Temperatures in the transition range from folded to unfolded state were selected and the rate constants of irreversible inactivation determined. Inactivation followed first-order kinetics and trehalose reduced the observed rate constants of inactivation, pointing to a stabilizing effect on the irreversible inactivation step of thermal denaturation. However, if the contribution of reversible unfolding on the irreversible inactivation of cutinase was taken into account, i.e., considering the fraction of cutinase molecules in the reversible unfolded conformation, the intrinsic rate constants can be calculated. Based on the intrinsic rate constants it was concluded that trehalose does not delay the irreversible inactivation. This conclusion was further supported by comparing the activation energy of the irreversible inactivation in the absence and in the presence of trehalose. The apparent activation energy in the absence and in the presence of trehalose were 67 and 99 Kcal/mol, respectively. The activation energy calculated from intrinsic rate constants was higher in the absence (30 Kcal/mol) than in the presence of trehalose (16 Kcal/mol), showing that kinetics of the irreversible inactivation step increased in the presence of trehalose. In fact, trehalose stabilized only the reversible step of thermal denaturation of cutinase.
journal_name
Biotechnol Bioengjournal_title
Biotechnology and bioengineeringauthors
Baptista RP,Cabral JM,Melo EPdoi
10.1002/1097-0290(20001220)70:6<699::aid-bit13>3.0subject
Has Abstractpub_date
2000-12-20 00:00:00pages
699-703issue
6eissn
0006-3592issn
1097-0290pii
10.1002/1097-0290(20001220)70:6<699::AID-BIT13>3.0journal_volume
70pub_type
杂志文章abstract::Enterokinase and recombinant enterokinase light chain (rEK(L)) have been used widely to cleave fusion proteins with the target sequence of (Asp)(4)-Lys. In this work, we show that their utility as a site-specific cleavage agent is compromised by sporadic cleavage at other sites, albeit at low levels. Further degradati...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.10082
更新日期:2001-12-20 00:00:00
abstract::For the commercial exploitation of lipase biocatalysis to be successful, it is essential that effective supports are selected for lipase immobilization. In this study hydrophobic controlled-pore glasses have been used as model systems for the immobilization of Rhizomucor miehei lipase. The effect of pore diameter and ...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260431006
更新日期:1994-04-25 00:00:00
abstract::Several researchers have demonstrated that the presence of a heterologous protein in recombinant Escherichia coli elicits a response similar to the heat-shock response, which includes enhanced protease expression. The present work detects, quantifies, and characterizes intracellular protease activity in E. coli that a...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260420602
更新日期:1993-09-05 00:00:00
abstract::Trichoplusia ni larvae were infected with baculoviruses containing genes for the expression of ultraviolet optimized green fluorescent protein (GFPuv) and several product proteins. A GFP-specific optical probe was used to both excite the green fluorescent protein (lambda(ex) = 385 nm), and subsequently monitor fluores...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.10668
更新日期:2003-07-20 00:00:00
abstract::A novel reaction system was developed to maximize the catalytic efficiency of chloroperoxidase (CPO, from Caldariomyces fumago) toward the oxidation of hydrocarbons. The reaction system consisted of an organic/aqueous emulsion comprising pure substrate and aqueous buffer supplemented with the surfactant dioctyl sulfos...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.20769
更新日期:2006-05-05 00:00:00
abstract::The antibiotic, difficidin, and its hydroxylated derivative oxydifficidin, were synthesized by cultures of Bacillus subtilis grown on a complex medium. Maximum titers of about 200 and 130 mg/L, respectively, were obtained. In fermentations where the dissolved oxygen tension (DOT) was controlled, the maximum specific g...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260440818
更新日期:1994-10-01 00:00:00
abstract::This article describes the synthesis and regulation of beta(1-3)glucanase and protease enzymes from the cell lytic system of Oerskovia xanthineolytica LL-G109 in continuous culture using different concentrations of carbon source (glucose) and inducer (glucan). These two enzyme activities are the main components of a l...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260300507
更新日期:1987-10-05 00:00:00
abstract::Power densities and oxidation-reduction potentials (ORPs) of MFCs containing a pure culture of Shewanella oneidensis MR-1 were compared to mixed cultures (wastewater inoculum) in cube shaped, 1-, 2-, and 3-bottle batch-fed MFC reactor configurations. The reactor architecture influenced the relative power produced by t...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.22556
更新日期:2010-02-15 00:00:00
abstract::Contactless simultaneous positioning of micrometer-sized particles in suspension (e.g., copolymer beads, living cells, silicon microparts) can be performed using ultrasound. Current devices are capable of collecting particles into planes or lines by exciting a resonance in the fluid by means of a piezoelectric transdu...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.21315
更新日期:2007-08-01 00:00:00
abstract::Working conditions of a biochemical fuel cell formed by an oxygen cathode and a platinum bioanode in a Saccharomyces cerevisiae suspension metabolizing glucose are described. The biocell response in terms of bioanode potential and current drainage under different fermentation conditions is reported. A kinetic equation...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260171011
更新日期:1975-10-01 00:00:00
abstract::Cells usually spread on a synthetic substrate through bonds between receptors and chemical groups on the substrate (ligands). Therefore, it is valuable to study the effects of the average number density of these chemical groups and the average distance between them to model and predict the cell behavior. Poly(ethylene...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.22889
更新日期:2011-02-01 00:00:00
abstract::A two-member methane-utilizing mixed culture of bacteria, formed by combining two pure cultures isolated from a naturally occurring methane-utilizing mixed culture, was studied in continuous culture. From the nutritional requirements and substrate ranges of the pure cultures, a mechanism for the interspecific interact...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260221010
更新日期:1980-10-01 00:00:00
abstract::Activation of lignin peroxidase (LIP) in an organic solvent by reversed micelles was investigated. Bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT) was used as a surfactant to form a reversed micelle. Lyophilized LIP from an optimized aqueous solution exhibited no enzymatic activity in any organic solvents examined i...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.20277
更新日期:2004-11-20 00:00:00
abstract::Non-autologous somatic gene therapy is an alternate approach to delivering recombinant gene products through implantation of a "universal" donor cell line engineered to produce a therapeutic gene product. The cells are immunologically isolated by enclosure in immunoprotective microcapsules fabricated from alginate-pol...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/(SICI)1097-0290(19961120)52:4<472::AID-BIT
更新日期:1996-11-20 00:00:00
abstract::A generic "system on a plate" modular multicompartmental bioreactor array which enables microwell protocols to be transferred directly to the bioreactor modules, without redesign of cell culture experiments or protocols is described. The modular bioreactors are simple to assemble and use and can be easily compared wit...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.22671
更新日期:2010-05-01 00:00:00
abstract::Cell morphology is an important macroscopic indicator of cellular physiology and is increasingly used as a mean of probing culture state in vitro. Phase contrast microscopy (PCM) is a valuable tool for observing live cells morphology over long periods of time with minimal culture artifact. Two general approaches are c...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.26064
更新日期:2017-01-01 00:00:00
abstract::High throughput pretreatment (HTPH) and enzymatic hydrolysis systems are now vital for screening large numbers of biomass samples to investigate biomass recalcitrance over various pretreatment and enzymatic hydrolysis conditions. Although hydrothermal pretreatment is currently being employed in most high throughput ap...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.24951
更新日期:2013-11-01 00:00:00
abstract::Molecular descriptors represent structural and physicochemical features of compounds. They have been extensively used for developing statistical models, such as quantitative structure activity relationship (QSAR) and artificial neural networks (NN), for computer prediction of the pharmacodynamic, pharmacokinetic, or t...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.21214
更新日期:2007-06-01 00:00:00
abstract::The release kinetics of beta-galactosidase protein have been determined during small-scale ultrasonication of E. coli cells. Among several studied parameters, ionic strength and cell concentration have the least influence on the rate of protein recovery, whereas sample volume and acoustic power dramatically affect the...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/(sici)1097-0290(19980605)58:5<536::aid-bit
更新日期:1998-06-05 00:00:00
abstract::The impact of process environment changes on process performance is one of the most crucial process safety issues when cultivating mammalian cells in a bioreactor. In contrast, directed shifting of process parameters can also be used as an optimization tool providing higher cell and product yields. Compared to other s...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.21013
更新日期:2006-08-20 00:00:00
abstract::In order to carry out an effective enzyme reaction, the preparation of soluble-insoluble immobilized enzyme was investigated. Proteases were selected as model enzymes, and their immobilization was carried out by using an enteric coating polymer as a carrier. Among the polymers tested, methacrylic acid-methylacrylate-m...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260290612
更新日期:1987-04-01 00:00:00
abstract::The enzymatic hydrolysis of olive oil using Chromobacterium viscosum lipase B encapsulated in reversed micelles of dioctyl sodium sulfosuccinate (AOT) in isooctane was investigated in an ultrafiltration ceramic membrane reactor of tubular type, operating in a batch mode. Water concentration was found to be a critical ...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260410802
更新日期:1993-04-05 00:00:00
abstract::The bacterial consortium MPD-M, isolated from sediment associated with Colombian mangrove roots, was effective in the treatment of hydrocarbons in water with salinities varying from 0 to 180 g L(-1). Where the salinity of the culture medium surpassed 20 g L(-1), its effectiveness increased when the cells were immobili...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.10318
更新日期:2002-07-20 00:00:00
abstract::A newly designed batch calorimeter was used to investigate the degradability of some celluloses having varying degrees of crystallinity. The PTC of an aerobic culture of Cellulomonas uda ATCC 21399 obtained revealed a diauxic growth which is attributed to the presence of hemicellulose contaminating Avicel and MN300 ce...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260270711
更新日期:1985-07-01 00:00:00
abstract::A desirable feature of many therapeutic glycoprotein production processes is to maximize the final sialic acid content. In this study, the effect of applying a novel chemical analog of the sialic acid precursor N-acetylmannosamine (ManNAc) on the sialic acid content of cellular proteins and a model recombinant glycopr...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.26291
更新日期:2017-08-01 00:00:00
abstract::Anerobic biofilms with dominantly acidogenic bacteria were grown in fixed-bed recycle reactors. The influence of calcium concentration in the culture medium on biofilm mass accumulation, immobilized calcium concentration, and biofilm-specific activity was investigated. The results indicate that the biofilm mass accumu...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260450305
更新日期:1995-02-05 00:00:00
abstract::Models for the known glucose transporters in Aspergillus niger and for simple diffusion of glucose through the hyphal membrane were prepared. The results from the models were compared with fermentation data from published studies on citric acid. It was found that the purely physical and uncontrolled process of diffusi...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/(sici)1097-0290(20000220)67:4<451::aid-bit
更新日期:2000-02-20 00:00:00
abstract::The effector functions elicited by IgG antibodies strongly depend on the carbohydrate moiety linked to the Fc region of the protein. Therefore several approaches have been developed to rationally manipulate these glycans and improve the biological functions of the antibody. Overexpression of recombinant beta1,4-N-acet...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.20777
更新日期:2006-04-05 00:00:00
abstract::Short-chain carboxylic acids generated by various mixed- or pure-culture fermentation processes have been considered valuable precursors for production of bioalcohols. While conversion of carboxylic acids into alcohols is routinely performed with catalytic hydrogenation or with strong chemical reducing agents, here, a...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.24786
更新日期:2013-04-01 00:00:00
abstract::With a view toward reduction of graft loss, we explored pancreatic islet transplantation within fibrin matrices rendered pro-angiogenic by incorporation of minimal doses of vascular endothelial growth factor-A165 and platelet-derived growth factor-BB presented complexed to a fibrin-bound integrin-binding fibronectin d...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.25589
更新日期:2015-09-01 00:00:00