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1.
We have identified two types of invertases, one bound ionically and the other covalently to the particulate fraction in grains
of heat tolerant C 306 and heat susceptible WH 542 cultivars of wheat (Triticum aestivum L.). The cell walls contained a high level of invertase activity, of which 79.2–72.8% was extractable by 2 M NaCl and 14.9–21.1%
by 0.5% EDTA in C 306 and WH 542, respectively. The NaCl-released invertase constituted the predominant fraction. Using 5–100 mM
sucrose and pH range of 4.0–7.0, the apparent Michaelis constant (K
m, enzyme substrate affinity measure) of enzyme ranged from 5.73 to 16.06 mM for C 306 and from 6.08 to 19.86 mM for WH 542.
The V
max (maximum catalytic rate) values at these pH were higher in C 306 (0.63–11.04 μg sucrose hydrolysed min−1) than WH 542 (0.51–8.73 μg sucrose hydrolysed min−1). By employing photo-oxidation and by studying the effect of pH on K
m and V
max, the involvement of histidine and α-carboxyl groups at the active site of the enzyme was indicated. The two cultivars also
showed differential response in terms of thermodynamic properties of the enzyme i.e. energy of activation (E
a), enthalpy change (ΔH) and entropy change (ΔS). NaCl-released invertase showed differential response to metal ions in two cultivars suggesting their distinctive nature.
Mn2+, Cu2+, Hg2+, Mg2+, Zn2+ and Cd2+ were strong inhibitors in WH 542 as compared to C 306 while K+, Ca2+ were stimulators in both the cultivars. Overall the results suggest that genetic differences exist in wall bound invertase
properties of wheat grains as evident in its altered kinetic behaviour. 相似文献
2.
S. Tyagi R. R. Mir H. Kaur P. Chhuneja B. Ramesh H. S. Balyan P. K. Gupta 《Molecular breeding : new strategies in plant improvement》2014,34(1):167-175
Common wheat (Triticum aestivum L.) contributes substantially to global food and nutritional security. Thus, an important goal of wheat breeding is to develop high-yielding varieties with better nutritional quality and resistance to all major diseases. During the present study, in the background of a popular elite wheat cultivar PBW343, we pyramided eight quantitative trait loci (QTLs)/genes for four grain quality traits (high grain weight, high grain protein content, pre-harvest sprouting tolerance, and desirable high-molecular-weight glutenin subunits) and resistance against the three rusts. For pyramiding eight QTLs/genes, four improved PBW343 lines, each carrying different combinations of the desired QTLs/genes (developed by us earlier), were crossed in pairs to produce two single-cross F1 hybrids. The single-cross F1 hybrids were intercrossed to produce a double-cross hybrid (DCH). Using marker-assisted selection in five consecutive generations (DCHF1–DCHF5), four pyramided lines (PYLs) were selected, each with all the eight desired QTLs/genes in homozygous state. The phenotypic characterization of the progenies of these PYLs suggested that the genetic background of PBW343 was retained in all these four PYLs. Therefore, these PYLs should prove useful in future wheat breeding programs for improving not only the grain quality, but also the durability of resistance against all three rusts. Multi-year/multi-location trials are planned for these pyramided lines to evaluate their potential for release as a next-generation improved version of wheat cv. PBW343 for commercial cultivation. 相似文献
3.
The regulation of contents and activities of peroxidase (POX), diamine oxidase (DAO) and polyamine oxidase (PAO) were determined
in relation to polyamines and lignin content in wheat (Triticum aestivum L.) grains. Two cultivars WH 542 (heat susceptible) and PBW 343 (heat tolerant) were used. Activities of POX, DAO and PAO
were substantially higher in PBW 343 as compared with WH 542 and appeared to be independently regulated. POX and PAO showed
peak activities at mid-milky stage (15 d post anthesis) while the activity of DAO showed continuous decline. Histochemical
localization of POX and PAO in situ revealed their presence in the chalazal cell walls, crease and seed coat. Substantially higher activities of enzymes in PBW
343 correlated well with a higher degree of lignification in the chalazal cells as compared to WH 542. 相似文献
4.
In a multiple deletion mutanthxt1Δhxt2Δhxt3Δ hxt4Δsnf3Δ ofSaccharomyces cerevisiae growing on 2 % glucose, high-affinity glucose-uptake (lowK
m) was exhibited throughout growth on glucose in contrast to the wild-type, which exhibited the usual low-affinity to high-affinity
transition as the glucose in the medium was consumed. elevated levels of invertase activity throughout growth on glucose,
in this mutant as compared to the wild-type, indicate that glucose repression may be impaired. Howver, in a mutant containing
only theHXT2 gene (hxt1Δhxt3Δhxt4Δ snf3Δ), invertase levels were similar to those in the wild-type. It is likely, therefore, that some of these putative glucose transporters,
such asHXT2, also have regulatory roles in cellular metabolism. In triple hexose-kinase mutants, rapid (200-ms) measurements of initial
glucose-uptake revealed high-affinity glucose uptake (K
m approx. 2 mmol/L) while measurements on the slower 5-s scale clearly demonstrate that uptake is not linear over this longer
period. These results suggest that this high-affinity component does not require a functional hexose-kinase. 相似文献
5.
Effect of high temperature stress on polyamine catabolism and antioxidant enzyme activity in relation to glutathione, ascorbate
and proline accumulation was studied in five wheat (Triticum aestivum L.) genotypes (differently susceptible to temperature stress). High temperature significantly increased the activities of
superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), dehydroascorbate reductase
(DHAR), glutathione reductase (GR) and glutathione S-transferase (GST) in shoots of all genotypes. Higher activities of GPX in C 306, C 273 and APX in PBW 550, PBW 343 and PBW
534 demonstrate their important role in scavenging H2O2. Conversely, high temperature stress led to a significant decline in SOD, CAT, APX and GPX activities of roots with a subsequent
increase in diamine oxidase (DAO) and polyamine oxidase (PAO) activities especially in PBW 550 and PBW 343. The concentration
of ascorbic acid declined with the imposition of heat stress, however, polyamines responded to high temperature stress by
increasing spermidine and spermine levels and decreasing putrescine levels. After exposure to high temperature, proline accumulation
was significantly decreased in roots and increased in shoots though maximum concentration was achieved in C 306 genotype.
Apparently, the wheat seedlings respond to high temperature mediated increase in reactive oxygen species (ROS) production
by altering antioxidative defense mechanism and polyamine catabolism though differentially in five wheat genotypes. Among
five genotypes studied, C 306 and C 273 seem to be better protected against temperature stress. The results suggested that
shoots were more resistant against the destructive effects of ROS as is indicated by low levels of thiobarbituric acid reactive
substances under high temperature stress. 相似文献
6.
Effect of salicylic and abscisic acid administered through detached tillers on antioxidant system in developing wheat grains under heat stress 总被引:1,自引:0,他引:1
The mechanism imparting thermotolerance by salicylic acid (SA) and abscisic acid (ABA) is still unresolved using either spraying
technique or in vitro conditions. Alternative way of studying these effects under near in vivo conditions is through the use
of liquid culturing technique. Effects of SA and ABA (100 μM) on antioxidative enzymes, antioxidants and lipid peroxidation
were studied in detached tillers of three wheat (Triticum aestivum L.) cultivars PBW 343, C 306 (heat tolerant) and WH 542 (heat susceptible) cultured in a liquid medium. Ears were subjected
to heat shock treatment (45°C for 2 h) and then maintained at 25°C for 5 days. Heat shock treatment resulted in increased
peroxidase (POD) activity, while superoxide dismutase (SOD) and catalase (CAT) activities were reduced compared to control.
The decrease in CAT activity was more significant in susceptible cultivar WH 542. Concomitantly, content of α-tocopherol and
lipid peroxides increased in heat-treated wheat ears, whereas contents of total ascorbate level were reduced. Following treatment
with SA and ABA, activities of all three antioxidative enzymes increased in correspondence with an increase in ascorbate and
α-tocopherol content. Apparently, lipid peroxide content was reduced by SA in heat tolerant cultivars (PBW 343 and C 306)
whereas in susceptible cultivar it was decreased by ABA. The up-regulation of the antioxidant system by SA and ABA possibly
contributes to better tolerance against heat shock-induced oxidative damage in wheat grains. 相似文献
7.
Vishal Gupta Arun Khajuria V. K. Razdan Atul Kumar 《Archives Of Phytopathology And Plant Protection》2017,50(11-12):515-525
During last decades, stripe rust has emerged as a major disease of wheat causing considerable yield loss in northern western plain and northern hill zones of India. Considering significant impact of the disease on wheat crop, field experiments were conducted during rabi seasons of 2013 and 2015 to evaluate the effect of different abiotic factors in different varieties (HD 2967, RSP 561, Agra Local and PBW 343) on the progress and spread of the disease as well as development of a predictive model to predict the disease initiation and spread in the field. Statistical analysis of data revealed that existing of low temperature (10–12 °C), high relative humidity (90%) along with intermittent rainfall was found conducive for disease onset. Thermic variables (atmospheric, canopy and soil temperature) along with age of crop in the selected varieties showed significant positive correlation with disease severity. Step-wise regression showed high R2 of 0.919, 0.885, 0.967 and 0.956 for the predicative model of stripe rust in RSP 561, HD 2967, Agra Local and PBW 343, respectively. 相似文献
8.
Effects of putrescine (Put) on responses of wheat (Triticum aestivum) seedlings or detached tillers at mid-milky stage to high temperature (HT) stress were investigated. The heat tolerant cv. PBW 343 exhibited higher content of antioxidants and activities of antioxidative enzymes, while lower content of lipid peroxides as compared to the heat-sensitive cv. HD 2329. HT elevated peroxidase (POX) and superoxide dismutase (SOD) activities, while diamine oxidase (DAO) and polyamine oxidase (PAO) activities were reduced in roots, shoots and developing grains. Application of Put under HT further enhanced POX and SOD activities along with increased content of ascorbate and tocophereol in grains. Invariably POX and SOD revealed higher activities in roots while CAT, DAO and PAO activities were higher in shoots. The content of lipid peroxides was increased in roots and shoots of HT stressed seedlings but less in Put-treated cv. PBW 343. 相似文献
9.
The invertase of Lactobacillus reuteri CRL 1100 is a glycoprotein composed by a single subunit with a molecular weight of 58 kDa. The enzyme was stable below 45°C
over a wide pH range (4.5–7.0) with maximum activity at pH 6.0 and 37°C. The invertase activity was significantly inhibited
by bivalent metal ions (Ca++, Cu++, Cd++, and Hg++), β-mercaptoethanol, and dithiothreitol and partially improved by ethylenediaminetetraacetic acid. The enzyme was purified
32 times over the crude extract by gel filtration and ion-exchange chromatography with a recovery of 17%. The K
m
and Vmax values for sucrose were 6.66 mM and 0.028 μmol/min, respectively. An invertase is purified and characterized for the first
time in Lactobacillus, and it proved to be a β-fructofuranosidase.
Received: 13 August 1999 / Accepted: 15 September 1999 相似文献
10.
P. V. Ershov O. V. Gnedenko A. A. Molnar A. V. Lisitsa A. S. Ivanov A. I. Archakov 《Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry》2012,6(1):94-97
The analysis of kinetic and thermodynamic parameters of binding of peptide and nonpeptide dimerization inhibitors of HIV protease
(HIVp) to the enzyme monomers immobilized on an optical chip has been studied by surface plasmon resonance. The molecular
interactions were investigated at different inhibitor concentrations (0–80 μM) and temperatures (15–35°C). Determination of
kinetic (k
on, k
off), equilibrium (K
d), and thermodynamic (ΔG, ΔH, and -TΔS) has shown that both inhibitors are characterized by similar interaction parameters and the entropic term (-TΔS) of about −20 kcal/mol is the main driving force for the HIVp complex formation with the inhibitors, while the positive value
(14 kcal/mol) of the enthalpic term (ΔH) counteracted the complex formation. 相似文献
11.
The present study investigates the efficiency of Aspergillus niger to produce invertase, an industrially important enzyme by using powdered stem of Cympopogan caecius (Lemon grass) as sole substrate and sole carbon source for the microorganism. The molecular weight of invertase was estimated
to be 66–70 kDa by sodium do decyl sulphate poly acrylamide gel electrophoresis (SDS PAGE). The production of the enzyme was
studied at different pH scales ranging from pH 4.0 to 7.0 at a constant temperature of 30°C and 2% substrate concentration.
The maximum production of invertase (specific activity −0.0516 μk/mg protein) was obtained at pH 5.5 at 30°C temperature,
and incubation for 48 h. The activity was found to be stable at pH 5.5 for 30 min. The enzyme was found to be stable in the
temperature range of 20–55°C. The effect of divalent metal ions Cu2+, Fe2+, Co2+ on the activity of the enzyme invertase showed that these ions affected the activity by a certain factor. The study can be
further industrially exploited in a country-like India where lemon grass is found in plenty and can be used as substrate for
enzyme production. Moreover, the preparation of the substrate is also a simple process. 相似文献
12.
Syed Ali Imran Bokhari Farooq Latif Muhammad Ibrahim Rajoka 《World journal of microbiology & biotechnology》2009,25(3):493-502
Xylanases produced from a locally isolated strain of Thermomyces lanuginosus and its mutant derivative were purified to a yield of 39.1 and 42.83% with specific activities of 15,501 and 17,778 IU mg−1 protein, respectively. The purification consisted of two steps i.e., ammonium sulphate precipitation, and gel filtration
chromatography. The mutant enzyme showed high affinity for substrate, with a K
m of 0.098 mg ml−1 as compared to wild type enzyme showing K
m of not less than 0.112 mg ml−1. It was found that pH values of 8.1 and 7.3 were best for activity of the mutant and wild-type-derived enzymes, respectively.
The values of pK
a of the acidic limbs of both enzymes were the same (5.0 and 4.9, respectively) but the pK
a value of the basic limb was slightly increased, indicating the participation of a carboxyl group present in a non-polar environment.
Temperatures of 70 and 65°C were found optimal for mutant and wild-derived xylanase, respectively. Enzymes displayed a high
thermostability showing a half life of 31.79 and 6.0 min (5.3-fold improvement), enthalpy of denaturation (ΔH*) of 146.06 and 166.95 kJ mol−1, entropy of denaturation (ΔS*) of 101.44 and 174.67, and free energy of denaturation (ΔG*) of 110.25 and 105.29 kJ mol−1 for mutant- and wild-organism derived enzyme, respectively at 80°C. Studies on the folding and stability of cellulase-less
xylanases are important, since their biotechnological employments require them to function under extreme conditions of pH
and temperature. The kinetic and thermodynamic properties suggested that the xylanase from the mutant organism is better as
compared to xylanase produced from the wild type and previously reported strains of same species, and may have a potential
usage in various industrial fields. 相似文献
13.
Metabolic activities of different microorganisms (Bacillus subtilis, B. licheniformis and Aspergillus niger) and hydrolytic enzymes (concentrations: 1 to 200 mg enzyme solids g–1 feed) were studied individually and in combinations with respect to H2 and methane production from damaged wheat grains. Bacillus subtilis, B. licheniformis and pre-existing hydrogen producers (control) produced 45 to 64 l H2 kg–1 total solids and subsequently, with the help of added methanogens, 155 to 220 l methane kg–1 total solids could be produced. H2 production from damaged wheat grains could be decreased to 28% or enhanced up to 152% with respect to control, by employing various microbial and enzymatic treatments. Similarly, it has been made possible to vary methane production capacities from as low as 17% to as high as 110% with respect to control. 相似文献
14.
Jingyuan Ai John A. Broadwater Thomas M. Loehr Joann Sanders-Loehr B. G. Fox 《Journal of biological inorganic chemistry》1997,2(1):37-45
The stearoyl-acyl carrier protein Δ9 desaturase (Δ9D) uses an oxo-bridged diiron center to catalyze the NAD(P)H– and O2–dependent desaturation of stearoyl-ACP. Δ9D, ribonucleotide reductase, and methane monooxygenase have substantial similarities
in their amino acid primary sequences and the physical properties of their diiron centers. These three enzymes also appear
to share common features of their reaction cycles, including the binding of O2 to the diferrous state and the subsequent generation of transient diferric-peroxo and diferryl species. In order to investigate
the coordination environment of the proposed diferric-peroxo intermediate, we have studied the binding of azide to the diiron
center of Δ9D using optical, resonance Raman (RR), and transient kinetic spectroscopic methods. The addition of azide results
in the appearance of new absorption bands at 325 nm and 440 nm (k
app≈3.5 s–1 in 0.7 M NaN3, pH 7.8). RR experiments demonstrate the existence of two different adducts: an η1–terminal structure at pH 7.8 (14N3
– asymmetric stretch at 2073 cm–1, resolved into two bands with 15N14N2
–) and a μ-1,3 bridging structure at pH<7 (14N3
– asymmetric stretch at 2100 cm–1, shifted as a single band with 15N14N2
–). Both adducts also exhibit an Fe–N3 stretching mode at ≈380 cm–1, but no accompanying Fe–O–Fe stretching mode, presumably due to either protonation or loss of the oxo bridge. The ability
to form a μ-1,3 bridging azide supports the likelihood of a μ-1,2 bridging peroxide as a catalytic intermediate in the Δ9D
reaction cycle and underscores the adaptability of binuclear sites to different bridging geometries.
Received: 23 August 1996 / Accepted: 4 October 1996 相似文献
15.
Characean internodal cells generate receptor potential (ΔE
m) in response to mechanical stimuli. Upon a long-lasting stimulus, the cells generated ΔE
m at the moment of both compression and decompression, and the amplitude of ΔE
m at the moment of decompression, (ΔE
m)E, was larger than that at compression. The long-lasting stimulus caused a membrane deformation (ΔD
m) having two components, a rapid one, (ΔD
m)rapid, at the moment of compression and a slower one, (ΔD
m)slow, during the long-lasting compression. We assumed that (ΔD
m)slow might have some causal relation with the larger ΔE
m at (ΔE
m)E. We treated internodal cells with either HgCl2 or ZnCl2, water channel inhibitors, to decrease (ΔD
m)slow. Both inhibitors attenuated (ΔD
m)slow during compression. Cells treated with HgCl2 generated smaller (ΔE
m)E compared to nontreated cells. On the other hand, cells treated with ZnCl2 never attenuated (ΔE
m)E but, rather, amplified it. Thus, the amplitude of (ΔD
m)slow did not always show tight correlation with the amplitude of (ΔE
m)E. Furthermore, when a constant deformation was applied to an internodal cell in a medium with higher or lower osmotic value,
a cell having higher turgor always showed a larger (ΔE
m)E. Thus, we concluded that changes in tension at the membrane may be the most important factor to induce activation of mechanosensitive
Ca2+ channel. 相似文献
16.
Juan P. Ferrio José Luis Araus Ramon Buxó Jordi Voltas Jordi Bort 《Vegetation History and Archaeobotany》2005,14(4):510-517
Carbon isotope discrimination (Δ13C) in charred grains from archaeological sites provides reliable information about water availability of ancient crops. However,
as cereals are cultivated plants, they may reflect not only climatic fluctuations, but also the effect on water status of
certain agronomic practices, such as sowing in naturally wet soils or irrigation. In this work, we propose a methodological
approach to combine Δ13C data from different plant species, in order to discriminate between climate-derived and anthropogenic effects on ancient
crops. We updated previous models for estimating water inputs from Δ13C of cereal grains of Hordeum vulgare and Triticum aestivum/durum, and we applied them to published data from several archaeological sites, including samples from the Neolithic to the present
day in northeast and southeast Spain, as well as from the Neolithic site of Tell Halula (northwest Syria). We found an important
decrease in water availability from the Neolithic to the present time in the three areas of study, especially clear for the
two driest areas (southeast Spain and northwest Syria). Potential differences in water management practices between wheat
and barley, as well as between cereal and legume crops (Vicia faba and Lens culinaris), are also discussed on the basis of the comparison of Δ13C values across several archaeological sites. 相似文献
17.
18.
Claudia Hackenberg Annerose Engelhardt Hans C. P. Matthijs Floyd Wittink Hermann Bauwe Aaron Kaplan Martin Hagemann 《Planta》2009,230(4):625-637
In cyanobacteria, photorespiratory 2-phosphoglycolate (2PG) metabolism is mediated by three different routes, including one
route involving the glycine decarboxylase complex (Gcv). It has been suggested that, in addition to conversion of 2PG into
non-toxic intermediates, this pathway is important for acclimation to high-light. The photoreduction of O2 (Mehler reaction), which is mediated by two flavoproteins Flv1 and Flv3 in cyanobacteria, dissipates excess reductants under
high-light by the four electron-reduction of oxygen to water. Single and double mutants defective in these processes were
constructed to investigate the relation between photorespiratory 2PG-metabolism and the photoreduction of O2 in the cyanobacterium Synechocystis sp. PCC 6803. The single mutants Δflv1, Δflv3, and ΔgcvT, as well as the double mutant Δflv1/ΔgcvT, were completely segregated but not the double mutant Δflv3/ΔgcvT, suggesting that the T-protein subunit of the Gcv (GcvT) and Flv3 proteins cooperate in an essential process. This assumption
is supported by the following results: (1) The mutant Δflv3/ΔgcvT showed a considerable longer lag phase and sometimes bleached after shifts from slow (low light, air CO2) to rapid (standard light, 5% CO2) growing conditions. (2) Photoinhibition experiments indicated a decreased ability of the mutant Δflv3/ΔgcvT to cope with high-light. (3) Fluorescence measurements showed that the photosynthetic electron chain is reduced in this mutant.
Our data suggest that the photorespiratory 2PG-metabolism and the photoreduction of O2, particularly that catalyzed by Flv3, cooperate during acclimation to high-light stress in cyanobacteria.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Mitoraj MP Parafiniuk M Srebro M Handzlik M Buczek A Michalak A 《Journal of molecular modeling》2011,17(9):2337-2352
The present study characterizes changes in the electronic structure of reactants during chemical reactions based on the combined
charge and energy decomposition scheme, ETS-NOCV (extended transition state–natural orbitals for chemical valence). Decomposition
of the activation barrier, ΔE
#, into stabilizing (orbital interaction, ΔE
orb, and electrostatic, ΔE
elstat) and destabilizing (Pauli repulsion, ΔE
Pauli, and geometry distortion energy, ΔE
dist) factors is discussed in detail for the following reactions: (I) hydrogen cyanide to hydrogen isocyanide, HCN → CNH isomerization; (II) Diels-Alder cycloaddition of ethene to 1,3-butadiene; and two catalytic processes, i.e., (III) insertion of ethylene into the metal-alkyl bond using half-titanocene with phenyl-phenoxy ligand catalyst; and (IV) B–H bond activation catalyzed by an Ir-containing catalyst. Various reference states for fragments were applied in ETS-NOCV
analysis. We found that NOCV-based deformation densities (Δρ
i) and the corresponding energies ΔE
orb(i) obtained from the ETS-NOCV scheme provide a very useful picture, both qualitatively and quantitatively, of electronic
density reorganization along the considered reaction pathways. Decomposition of the barrier ΔE# into stabilizing and destabilizing contributions allowed us to conclude that the main factor responsible for the existence
of positive values of ΔE
# for all processes (I, II, III and IV) is Pauli interaction, which is the origin of steric repulsion. In addition, in the case of reactions II, III and IV, a significant degree of structural deformation of the reactants, as measured by the geometry distortion energy, plays an
important role. Depending on the reaction type, stabilization of the transition state (relatively to the reactants) originating
either from the orbital interaction term or from electrostatic attraction can be of vital importance. Finally, use of the
ETS-NOCV method to describe catalytic reactions allows extraction of information on the role of catalysts in determination
of ΔE
#. 相似文献
20.
Ying Zhou Takeshi Minami Kohsuke Honda Takeshi Omasa Hisao Ohtake 《Applied microbiology and biotechnology》2010,87(2):647-655
Systematic screening of single-gene knockout collection of Escherichia coli BW25113 (the Keio collection) was performed to select mutants that could enhance the deethylation of 7-ethoxycoumarin catalyzed
by CYP154A1. After 96-well plate high-throughput screening followed by test tube assays, four mutants (ΔcpxA, ΔgcvR, ΔglnL, and an unknown-gene-deleted one (Δuk)) were able to increase the CYP154A1 activity by approximately 1.4–1.7 times compared with that of the control strain. When
new mutants were constructed by disrupting individually the cpxA, gcvR, glnL, and uk genes in E. coli BW25113, three of them (ΔcpxA, ΔgcvR, and ΔglnL) showed high levels of CYP154A1 activity. However, the uk-disruptant failed to enhance the CYP154A1 activity, suggesting that the high CYP154A1 activity of the Δuk mutant in the Keio collection was due to a spontaneous mutation in the chromosome. In-frame deletion mutants of ΔcpxA, ΔgcvR, and ΔglnL also exhibited high enzyme activity, and complementation of these mutations could decrease CYP154A1 activity. These results
indicated that the enhancement of the enzyme activity was not caused by polar effects on their neighbor genes. To our knowledge,
this is the first report on a genome-wide screening of the genes for deletion to improve the activity of a recombinant whole-cell
biocatalyst. 相似文献