Abstract:
:The addition of simple inorganic salts to aqueous enzyme solutions prior to lyophilization results in a dramatic activation of the dried powder in organic media relative to enzyme with no added salt. Activation of both the serine protease subtilisin Carlsberg and lipase from Mucor javanicus resulting from lyophilization in the presence of KCl was highly sensitive to the lyophilization time and water content of the sample. Specifically, for a preparation containing 98% (w/w) KCl, 1% (w/w) phosphate buffer, and 1% (w/w) enzyme, varying the lyophilization time showed a direct correlation between water content and activity up to an optimum, beyond which the activity decreased with increasing lyophilization time. The catalytic efficiency in hexane varied as much as 13-fold for subtilisin Carlsberg and 11-fold for lipase depending on the lyophilization time. This dependence was apparently a consequence of including the salt, as a similar result was not observed for the enzyme freeze-dried without KCl. In the case of subtilisin Carlsberg, the salt-induced optimum value of kcat/Km for transesterification in hexane was over 20,000-fold higher than that for salt-free enzyme, a substantial improvement over the previously reported enhancement of 3750-fold (Khmelnitsky, 1994). As was found previously for pure enzyme, the salt-activated enzyme exhibited greatest activity when lyophilized from a solution of pH equal to the pH for optimal activity in water. The active-site content of the lyophilized enzyme samples also depended upon lyophilization time and inclusion of salt, with opposite trends in this dependence observed for the solvents hexane and tetrahydrofuran. Finally, substrate selectivity experiments suggested that mechanism(s) other than selective partitioning of substrate into the enzyme-salt matrix are responsible for salt-induced activation of enzymes in organic solvents.
journal_name
Biotechnol Bioengjournal_title
Biotechnology and bioengineeringauthors
Ru MT,Dordick JS,Reimer JA,Clark DSdoi
10.1002/(sici)1097-0290(19990420)63:2<233::aid-bitsubject
Has Abstractpub_date
1999-04-20 00:00:00pages
233-41issue
2eissn
0006-3592issn
1097-0290pii
10.1002/(SICI)1097-0290(19990420)63:2<233::AID-BITjournal_volume
63pub_type
杂志文章abstract::A denitrifying consortium capable of transforming carbon tetrachloride (CCl(4)) was cultured from aquifer sediment from the U.S. Department of Energy's Hanford Site in southeastern Washington State. To understand the kinetics of the biological destruction of CCl(4) by these microbes, a set of experiments, the conditio...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260430613
更新日期:1994-03-15 00:00:00
abstract::Animal cell cultivation in vitro has been studied for more than 40 years. However, the culture medium composition has not been designed on the basis of the stoichiometric nutritional demands for animal cell growth. In this article, a model was developed to study the stoichiometric demands for nutrients (including gluc...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260431122
更新日期:1994-05-01 00:00:00
abstract::For all bacteria, nearly every antimicrobial fails since a subpopulation of the bacteria enter a dormant state known as persistence, in which the antimicrobials are rendered ineffective due to the lack of metabolism. This tolerance to antibiotics makes microbial infections the leading cause of death worldwide and make...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.25963
更新日期:2016-09-01 00:00:00
abstract::The yeast Pachysolen tannophilus was entrapped in calcium alginate beads to ferment D-xylose on a continous basis in the presence of high cell densities. Experimental operating variables included the feed D-xylose concentration, the dilution rate, and the fermentor biomass concentration. Under favorable operating cond...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260241010
更新日期:1982-10-01 00:00:00
abstract::Esters were prepared by acylation of hydroxypropyl cellulose with fatty acid catalyzed by immobilized lipase from Candida antarctica in tert-butanol. The nature of the substrates used, the initial water activity of the system, and the molecular weight of the hydroxypropyl cellulose were investigated. Moreover, Fourier...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/1097-0290(20010220)72:4<495::aid-bit1012>3
更新日期:2001-02-20 00:00:00
abstract::Modifications are made to an earlier thermodynamic model (TEEM1) for prediction of maximum microbial yields from aerobic and anaerobic as well as heterotrophic and autotrophic growth. The revised model (TEEM2) corrects for lower yields found with aerobic oxidations of organic compounds where an oxygenase is involved a...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.21250
更新日期:2007-06-01 00:00:00
abstract::A microarray presenting glycerol nanodroplets of fluorogenic peptide substrates was used as a biosensor for the detection of multiple enzyme activities within human plasma. Using 10 different plasma proteases (kallikrein, factor XIIa, factor XIa, factor IXa, factor VIIa, factor Xa, thrombin, activated protein C, uPA a...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.20927
更新日期:2006-08-20 00:00:00
abstract::We report the isolation of mutant strains of the methylotrophic yeast Hansenula polymorpha that are able to efficiently oxidize ethanol to acetaldehyde in an intact cell system. The oxidation reaction is catalyzed by alcohol oxidase (AOX), a key enzyme in the methanol metabolic pathway that is typically present only i...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/(sici)1097-0290(20000405)68:1<44::aid-bit5
更新日期:2000-04-05 00:00:00
abstract::Protein glycosylation, or the attachment of sugar moieties (glycans) to proteins, is important for protein stability, activity, and immunogenicity. However, understanding the roles and regulations of site-specific glycosylation events remains a significant challenge due to several technological limitations. These limi...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.26502
更新日期:2018-03-01 00:00:00
abstract::Copolymers of N-isopropylacrylamide and N-acryloyl amino acid spacers of varying chain length were synthesized. p-Aminobenzamidine (PABA) was chemically linked to the pendant carboxyl groups of these polymers to obtain thermoprecipitating affinity polymers. The inhibition constant (Ki) of these polymers for trypsin de...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/(sici)1097-0290(19990820)64:4<418::aid-bit
更新日期:1999-08-20 00:00:00
abstract::10-Deacetylabaccatin III (10 DAB), an important precursor for paclitaxel semisynthesis, is enhanced in yew extracts using C10-deacetylase and C13-deacylase enzymes.(4) C10-deacetylase is an intracellular enzyme produced by the fermentation of a soil microorganism, Nocardioides luteus (SC 13912). During the fermentatio...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260480518
更新日期:1995-12-05 00:00:00
abstract::Flocculation of yeast cells occurs during the fermentation of beer. Partway through the fermentation the cells become flocculent and start to form flocs. If the environmental conditions, such as medium composition and fluid velocities in the tank, are optimal, the flocs will grow in size large enough to settle. After ...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/(sici)1097-0290(19980205)57:3<330::aid-bit
更新日期:1998-02-05 00:00:00
abstract::Trypsin and alpha-chymotrypsin were immobilized by gelentrapment in polyacrylamide cross-linked with N,N(1)-methylenebisacrylamide. The immobilized enzymes are catalytically efficient in suspensions of reverse micelles formed in isooctane by bis(2-ethylhexyl) sodium sulfosuccinate (AOT) and water. Both entrapped enzym...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260331008
更新日期:1989-04-20 00:00:00
abstract::A model that portrays substrate profiles in a steady-state multispecies granular biofilm is developed and coupled with a biofilm detachment model. The model accounts for glucose, propionate, hydrogen, and acetate transformations performed by three bacterial trophic groups: acidogens, syntrophic bacterial consortia, an...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/(SICI)1097-0290(19970420)54:2<122::AID-BIT
更新日期:1997-04-20 00:00:00
abstract::Three-dimensional cell culture models, such as spheroids, can be used in the process of the development of new anticancer agents because they are able to closely mimic the main features of human solid tumors, namely their structural organization, cellular layered assembling, hypoxia, and nutrient gradients. These prop...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章,评审
doi:10.1002/bit.26845
更新日期:2019-01-01 00:00:00
abstract::The influence of microheterogeneity on enzyme inactivation kinetics is examined. A continuous normal distribution of the thermal activation energy is assumed, and using this, a simple mathematical model is developed to find the activity-time trajectories for a microheterogeneous enzyme. Using an example, the model is ...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260300116
更新日期:1987-07-01 00:00:00
abstract::The application of rational design in reallocating metabolic flux to accumulate desired chemicals is always restricted by the native regulatory network. In this study, recombinant Pichia pastoris was constructed for malic acid production from sole methanol through rational redistribution of metabolic flux. Different m...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.27575
更新日期:2021-01-01 00:00:00
abstract::An option for fertility preservation for women facing a cancer diagnosis involves the cryopreservation of ovarian tissue for later re-transplantation or in vitro culture, with in vitro culture preferred to avoid reintroduction of the cancer. Small, immature follicles survive the freeze-thaw process, and can be matured...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.22250
更新日期:2009-06-01 00:00:00
abstract::The gp41 polypeptide of human immunodeficiency virus (HIV) contains an immunosuppressive domain, an epitope which elicits specific cytolytic T cell responses to HIV, and a complement Clq interactive domain. In addition, a synthetic peptide called CS3, derived from gp41 (amino acids 576-593 of gp160) and contiguous wit...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260420111
更新日期:1993-06-05 00:00:00
abstract::This study conducted quantitative kinetic modeling and in situ and temporally resolved measurements of adsorption, desorption, and re-adsorption of a commercial endoglucanase in lignocellulosic suspensions. The study defined a cellulase adsorption and desorption competition parameter, a pseudo rate of binding and deso...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.24483
更新日期:2012-08-01 00:00:00
abstract::Modification of cellular functions by overexpression of genes is being increasingly practiced for tissue engineering. In the present study, we investigated whether transfection efficiency could be enhanced by magnetofection that involves the use of plasmid DNA (pDNA)/magnetite cationic liposomes (MCLs) complexes (pDNA...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.21738
更新日期:2008-05-01 00:00:00
abstract::In large-scale mammalian cell culture, the key toxic by-products assessed and monitored are lactate and ammonia. Often no distinction between the two isoforms of lactate is made. Here, we present profiles of both D- and L-lactate. D-Lactate is the end molecule of the methylglyoxal pathway. D-Lactate unlike L-lactate i...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.22757
更新日期:2010-09-01 00:00:00
abstract::Self-cycling fermentation (SCF), a cyclical, semi-continuous process that induces cell synchrony, was incorporated into a recombinant protein production scheme. Escherichia coli CY15050, a lac(-) mutant lysogenized with temperature-sensitive phage λ modified to over-express β-galactosidase, was used as a model system....
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.24492
更新日期:2012-09-01 00:00:00
abstract::The dissociation constant, K(d) , is an important parameter for characterizing protein-protein interaction affinities. SUMOylation is one of the important protein post-translational modifications and it involves a multi-step enzymatic cascade reaction, resulting in peptide activation and substrate conjugation. Multipl...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.24564
更新日期:2012-11-01 00:00:00
abstract::Five microbial inocula were evaluated in batch tests for the ability to remediate mine drainage (MD). Dairy manure (DM), anaerobic digester sludge, substrate from the Luttrell (LUTR) and Peerless Jenny King (PJK) sulfate-reducing permeable reactive zones (SR-PRZs) and material from an MD-treatment column that had been...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.21930
更新日期:2008-11-01 00:00:00
abstract::The feasibility of continuous production of proteins in chemostat cultures of Bacillus subtilis was investigated. An expression system consisting of the bacterium B. subtilis BR151 carrying plasmid p602/19 was used. The plasmid contains the cat (chioramphenicol acetyltrans-ferase) gene downstream of a strong vegetativ...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260470503
更新日期:1995-09-05 00:00:00
abstract::The effects of low intensity pulsed ultrasound (LIPUS) on proliferation and chondrogenic differentiation of human mesenchymal stem cells (hMSCs) seeded on 3D printed poly-(ethylene glycol)-diacrylate (PEG-DA) scaffolds with varying pore geometries (square and hexagonal channels) were investigated. The scaffold with sq...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.26480
更新日期:2018-02-01 00:00:00
abstract::The thermo-responsive polymer poly(N-isopropylacrylamide) has received widespread attention for its in vitro application in the non-invasive, non-destructive release of adherent cells on two dimensional surfaces. In this study, 3D non-woven scaffolds fabricated from poly(propylene) (PP), poly(ethylene terephthalate) (...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.24469
更新日期:2012-08-01 00:00:00
abstract::The effects of growing Clostridium acetobutylicum NCIB 8052 in a chemostat under conditions of glucose, NH(4) (+), PO(4) (3-), Mg(2+), and Fe(2+) limitation were examined. It was noted that limitation of any major nutrient resulted in the same fermentation pattern. Conditions where minor nutrient levels were reduced a...
journal_title:Biotechnology and bioengineering
pub_type: 杂志文章
doi:10.1002/bit.260290315
更新日期:1987-02-01 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