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1.
To investigate the production of cellulases and xylanases from Penicillium echinulatum 9A02S1, solid-state fermentation (SSF) was performed by using different ratios of sugar cane bagasse (SCB) and wheat bran
(WB). The greatest filter paper activity obtained was 45.82 ± 1.88 U gdm−1 in a culture containing 6SCB/4WB on the third day. The greatest β-glucosidase activities were 40.13 ± 5.10 U gdm−1 obtained on the third day for the 0SCB/10WB culture and 29.17 ± 1.06 U gdm−1 for the 2SCB/8WB culture. For endoglucanase, the greatest activities were 290.47 ± 43.57 and 276.84 ± 15.47 U gdm−1, for the culture 6SCB/4WB on the fourth and fifth days of cultivation, respectively. The greatest xylanase activities were
found on the third day for the cultures 6SCB/4WB (36.38 ± 5.38 U gdm−1) and 4SCB/6WB (37.87 ± 2.26 U gdm−1). In conclusion, the results presented in this article showed that it was possible to obtain large amounts of cellulases
and xylanases enzymes using low-cost substrates, such as SCB and WB. 相似文献
2.
A novel laccase producing Basidiomycete Peniophora sp. (NFCCI-2131) was isolated from pulp and paper mill effluent. The optimal temperature and initial pH for laccase production
by the isolate in submerged culture were found to be 30 and 4.6° C, respectively. Maltose (20 g l−1) and tryptone (1.0 g l−1) were the most suitable carbon and nitrogen sources for laccase production. Cu2+ (1.0 mM) and veratryl alcohol induced maximum laccase production giving 6.6 and 6.07 U/ml laccase activity, respectively.
Under optimised culture conditions, 7.6 U/ml activity was obtained, which was 2.4 times higher than that was achieved in basal
medium. An evaluation of the delignification efficiency of the crude enzyme in the presence of redox mediators [2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonic
acid) and (1-hydroxybenzotriazole)] revealed structural changes in lignin and existence of many active centres for both chemical
and biological degradation of lignin following enzymatic treatment. 相似文献
3.
A feeding technology that was suitable for improving the nisin production by Lactococcus lactis subsp. lactis W28 was established. The effects of initial sucrose concentration (ISC) in the fermentation broth, feeding time, and feeding
rate on the fermentation were studied. It was observed that a fed-batch culture (ISC = 10 g l−1) with 100 ml sucrose solution (190 g l−1) being evenly fed (9–10 ml h−1) into the fermenter after 3-h fermentation gave the best performance in terms of biomass and nisin yield. Under these conditions,
the total biomass and the total nisin yield were approximately 23% and 51% higher than those in batch fermentation, respectively.
When the sucrose concentration was controlled at 5–10 g l−1 in variable volume intermittent fed-batch fermentation (VVIF) with ISC = 10 g l−1, the total biomass and the total nisin yield were 29% and 60% above those in batch fermentation, respectively. The VVIF proved
to be effective to eliminate the substrate inhibition by maintaining sucrose at appropriate levels. It is also easy to be
scaled up, since various parameters involved in industrial production were taken into account. 相似文献
4.
Hong WK Rairakhwada D Seo PS Park SY Hur BK Kim CH Seo JW 《Applied biochemistry and biotechnology》2011,164(8):1468-1480
In the present study, a novel oleaginous Thraustochytrid containing a high content of docosahexaenoic acid (DHA) was isolated
from a mangrove ecosystem in Malaysia. The strain identified as an Aurantiochytrium sp. by 18S rRNA sequencing and named KRS101 used various carbon and nitrogen sources, indicating metabolic versatility. Optimal
culture conditions, thus maximizing cell growth, and high levels of lipid and DHA production, were attained using glucose
(60 g l−1) as carbon source, corn steep solid (10 g l−1) as nitrogen source, and sea salt (15 g l−1). The highest biomass, lipid, and DHA production of KRS101 upon fed-batch fermentation were 50.2 g l−1 (16.7 g l−1 day−1), 21.8 g l−1 (44% DCW), and 8.8 g l−1 (40% TFA), respectively. Similar values were obtained when a cheap substrate like molasses, rather than glucose, was used
as the carbon source (DCW of 52.44 g l−1, lipid and DHA levels of 20.2 and 8.83 g l−1, respectively), indicating that production of microbial oils containing high levels of DHA can be produced economically when
the novel strain is used. 相似文献
5.
Zhixin Wang Yujie Cai Xiangru Liao Feng Zhang Dabing Zhang Zhiling Li 《Applied biochemistry and biotechnology》2010,162(1):280-294
A new white-rot fungus SYBC-L1, which could produce an extracellular laccase, was isolated from a decayed Elaeocarpus sylvestris. The strain was identified as Pycnoporus sp. SYBC-L1 according to the morphological characteristics and ribosomal ITS1-5.8S-ITS2 RNA genomic sequence analysis. The
highest laccase activity of 24.1 U ml−1, which was approximately 40-fold than that in basal medium, was achieved in optimal culture medium in submerged fermentation.
The laccase produced by Pycnoporus sp. SYBC-L1 was not only a cold adaptation enzyme with a relative catalytic activity of 30.2% at 0°C but also a high thermostable
enzyme. The half-lives at 60, 70 and 80°C were 85.5, 37.2, and 2.6 h, respectively. The laccase could effectively decolorize
weak acid blue AS and diamond black PV up to 88% and 74.7%, respectively, within 2 h in the absence of any redox mediators.
The results suggested Pycnoporus sp. SYBC-L1 was a potential candidate for laccase production and industrial application. 相似文献
6.
Liu GQ Xiao HX Wang XL Zhao Y Zhang YG Ren GP 《Applied biochemistry and biotechnology》2011,165(1):87-97
The medicinal fungus Ganoderma lucidum was inoculated into the media with and without supplementation of medicinal insect extracts to screen stimulators from Chinese
medicinal insects for mycelial growth and triterpenoids production in submerged fermentation. The methanol and ether extracts
of the tested insects had no significant stimulatory effect on the mycelial biomass production (P > 0.05), and those of H. remigator and Mylabris phalerata markedly inhibited the mycelial growth. However, the ether extract of Catharsius molossus at a concentration of 200 mg l−1 led to a significant increase in triterpenoids concentration from 231.7 ± 9.77 to 313.7 ± 10.6 mg l−1 (P < 0.01). Analysis of fermentation kinetics of G. lucidum suggests that glucose concentration in the extract of C. molossus-added group decreased more quickly as compared to the control group from day 2 to day 7 of fermentation process, while the
triterpenoids biosynthesis was promoted at the same culture period. However, the culture pH profile was not affected by the
addition of the extract. Chemical study of the extract show that cis-9,10-methylenehexadecanoic acid (9,10-MEA) and hexadecanoic acid (especially 9,10-MEA) were the key active compounds of the
extract responsible for the stimulatory effect on the triterpenoids production. 相似文献
7.
D. T. Souza A. S. R. Bispo E. P. S. Bon R. R. R. Coelho R. P. Nascimento 《Applied biochemistry and biotechnology》2012,166(6):1575-1585
In the present paper, endo-β-1,4-xylanase production by Aspergillus fumigatus was evaluated in solid-state fermentation using low-cost substrates such as sugarcane bagasse (SCB), brewer’s spent grain
(BSG), and wheat bran (WB). The partial characterization of the crude enzyme was also performed. In the experimental conditions,
the highest levels of endo-β-1,4-xylanase production by A. fumigatus FBSPE-05 occurred within 8 days incubation when using SCB/liquid medium at 1:2 ratio (219.5 U g−1) and 4 days incubation when using WB/liquid medium at 1:1 ratio (215.6 U g−1). Crude enzyme from this last condition was used to enzyme characterization, showing best enzyme activity at 60 °C and pH 6.0,
which suggests a thermophilic endoxylanase. The crude enzyme retained 73% of its activity after 1 h at 60 °C, and zymogram
has shown three bands of endo-β-1,4-xylanase activity, with different molecular masses. A. fumigatus FBSPE-05 was able to grow and produce good levels of endo-β-1,4-xylanase using agro-industrial by-products, making this strain
worthy for further investigation. To our knowledge, this is the first study reporting the use of SCB and/or BSG as sole substrates
for endoxylanase production by solid-state fermentation using A. fumigatus. 相似文献
8.
Donata Iandolo Alessandra Piscitelli Giovanni Sannia Vincenza Faraco 《Applied biochemistry and biotechnology》2011,163(1):40-51
A process of solid state fermentation (SSF) on tomato pomace was developed with the white-rot fungi Pleurotus ostreatus and Trametes versicolor, using sorghum stalks as support. Operative parameters (humidity, water activity, and size of substrate particles) guaranteeing
a good colonization of tomato pomace by both fungi were defined and conditions for production at high titers of the industrially
relevant enzymes laccase, xylanase and protease were identified. Significant laccase activity levels (up to 36 U g−1 dry matter) were achieved without any optimization of culture conditions, neither by nutrient addition nor by O2 enrichment. Furthermore, protease activity levels up to 34,000 U g−1 dry matter were achieved, being higher than those reported for the fungi typically considered as the best protease producers
such as Aspergillus strains. Moreover, as one of the most significant results of this study, analysis of P. ostreatus tomato SSF samples by zymogram revealed two bands with laccase activity which had not been detected so far. 相似文献
9.
Wei Zhao Aisheng Xiong Xiaoyan Fu Feng Gao Yongsheng Tian Rihe Peng 《Applied biochemistry and biotechnology》2010,162(8):2157-2165
To obtain a high level expression of phytase with favorable characteristics, a codon-optimized phytase gene from Citrobacter freundii was synthesized and transferred into Pichia pastoris. Small-scale expression experiments and activity assays were used to screen positive colonies. After purified by Ni2+–NTA agarose affinity column, the characterizations of the recombinant phytase were determined. The recombinant phytase (r-phyC)
had two distinct pH optima at 2.5 and 4.5 and an optimal temperature at 50 °C. It retained more than 80% activity after being
incubated under various buffer (pH 1.5–8.0) at 37 °C for 1 h. The specific activity, Km, and Vmax values of r-phyC for sodium phytate were 2,072 ± 18 U mg−1, 0.52 ± 0.04 mM, and 2,380 ± 84 U mg−1 min−1, respectively. The enzyme activity was significantly improved by 1 mM of K+, Ca2+, and Mg2+. These characteristics contribute to its potential application in feed industry. 相似文献
10.
Mervat Morsy A. El-Gendy 《Applied biochemistry and biotechnology》2010,162(3):780-794
Among all endophytic keratinolytic fungal isolates recovered from marine soft coral Dendronephthya hemprichii, Penicillium spp. Morsy1 was selected as the hyperactive keratinolytic strain under solid substrate fermentation of different agriculture
and poultry wastes. The optimization of extraction process, physicochemical parameters affecting the keratinase production
in solid-state fermentation, and the purified keratinase parameters were studied. Maximum keratinase activity (1,600 U g−1, initial dry substrate) was recovered from moldy bran with 0.1% Tween 80. The optimized production conditions were rice straw
as carbon source, pH of medium 6, growth temperature 26 °C, initial moisture content of 80% (v/w), inoculum size of 105 spores ml−1, and an average particle size of the substrate 0.6 mm (3,560 U g−1, initial dry substrate after 5 days of fermentation). Two types of keratinase (Ahm1 and Ahm2) were purified from the culture
supernatant through ammonium sulfate precipitation, DEAE-Sepharose, and gel filtration chromatography. Enzyme molecular weights
were 19 kDa (Ahm1) and 40 kDa (Ahm2). The kinetic parameters of purified keratinases were optimized for the hydrolysis of
azokeratin by Ahm1 (pH 7.0–8.0, stable in pH range of 6.0 to 8.0 at 50 °C) and Ahm2 enzymes (pH 10.0–11.0, stable in pH range
of 6.0 to 11.0 at 60–65 °C). Whereas inhibitors of serine (phenylmethylsulfonyl fluoride) and cysteine (iodoacetamide) proteases
had minor effects on both Ahm1 and Ahm2 activity, both keratinases were strongly inhibited by chelating agents EDTA and EGTA.
These findings suggest that serine and cysteine residues are not involved in the catalytic mechanisms, and they are metalloproteases. 相似文献
11.
A laccase has been purified from the liquid culture growth medium containing bagasse particles of Fomes durissimus. The method involved concentration of the culture filtrate by ultrafiltration and anion exchange chromatography on diethyl
aminoethyl cellulose. The sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE) and native polyacrylamide
gel electrophoresis both gave single protein band indicating that the enzyme preparation was pure. The molecular mass of the
purified laccase determined from SDS-PAGE analysis was 75 kDa. Using 2,6-dimethoxyphenol as the substrate, the determined
K
m and k
cat values of the laccase are 182 μM and 0.35 s−1, respectively, giving a k
cat/K
m value of 1.92 × 103 M−1 s−1. The pH and temperature optimum were 4.0 and 35 °C, respectively. The purified laccase has yellow colour and does not show
absorption band around 610 nm found in blue laccases. Moreover, it transformed methylbenzene to benzaldehyde in the absence
of mediator molecules, property exhibited by yellow laccases. 相似文献
12.
Yun Wang Jin-Zhu Song Qian Yang Zhi-Hua Liu Xiao-Mei Huang Yan Chen 《Applied biochemistry and biotechnology》2010,162(3):843-854
A gene encoding chitin deacetylase was cloned by polymerase chain reaction from Aspergillus nidulans. Sequencing result showed 40% homology to the corresponding gene from Colletotrichum lindemuthianum. The complete gene contains an open reading frame of 747 nucleotides encoding a sequence of 249 amino acid residues. The
chitin deacetylase gene was subcloned into a pET28a expression vector and expressed in Escherichia coli BL21 and then purified by metal affinity chromatography using a His-bind column. The purified chitin deacetylase demonstrated
an activity of 0.77 U ml−1 for the glycol chitin substrates, and its specific activity was 4.17 U mg−1 for it. The optimal temperature and pH of the purified enzyme were 50 °C and 8.0, respectively. When glycol chitin was used
as the substrate, K
m was 4.92 mg ml−1, and K
cat showed 6.25 s−1, thus the ratio of K
cat and K
m was 1.27 ml s−1 mg−1. The activity of chitin deacetylase was affected by a range of metal ions and ethylenediaminetetraacetic acid. 相似文献
13.
Rodrigues TH Rocha MV de Macedo GR Gonçalves LR 《Applied biochemistry and biotechnology》2011,164(6):929-943
In this work, the potential of microwave-assisted alkali pretreatment in order to improve the rupture of the recalcitrant
structures of the cashew able bagasse (CAB), lignocellulosic by-product in Brazil with no commercial value, is obtained from
cashew apple process to juice production, was studied. First, biomass composition of CAB was determined, and the percentage
of glucan and lignin was 20.54 ± 0.70% and 33.80 ± 1.30%, respectively. CAB content in terms of cellulose, hemicelluloses,
and lignin, 19.21 ± 0.35%, 12.05 ± 0.37%, and 38.11 ± 0.08%, respectively, was also determined. Results showed that, after
enzymatic hydrolysis, alkali concentration exerted influence on glucose formation, after pretreatment with 0.2 and 1.0 mo L−1 of NaOH (372 ± 12 and 355 ± 37 mg gglucan−1) when 2% (w/v) of cashew apple bagasse pretreated by microwave-assisted alkali pretreatment (CAB-M) was used. On the other hand, pretreatment
time (15–30 min) and microwave power (600–900 W) exerted no significant effect on hydrolysis. On enzymatic hydrolysis step,
improvement on solid percentage (16% w/v) and enzyme load (30 FPU gCAB-M−1) increased glucose concentration to 15 g L−1. The fermentation of the hydrolyzate by Saccharomyces cerevesiae resulted in ethanol concentration and productivity of 5.6 g L−1 and 1.41 g L−1 h−1, respectively. 相似文献
14.
D. M. Ortega-Sotelo J. G. Gonzalez-Rodriguez M. A. Neri-Flores M. Casales L. Martinez A. Martinez-Villafañe 《Journal of Solid State Electrochemistry》2011,15(9):1997-2004
The corrosion inhibition of X-70 pipeline steel in saltwater saturated with CO2 at 50 °C with carboxyamido imidazoline has been evaluated by using electrochemical techniques. Techniques included polarization
curves, linear polarization resistance, electrochemical impedance, and electrochemical noise measurements. Inhibitor concentrations
were 0, 1.6 × 10−5, 3.32 × 10−5, 8.1 × 10−5, 1.6 × 10−4, and 3.32 × 10−4 mol l−1. All techniques showed that the best corrosion inhibition was obtained by adding 8.1 × 10−5 mol l−1 of carboxyamido imidazoline. For inhibitor concentrations higher than 8.1 × 10−5 mol l−1 a desorption process occurs, and an explanation has been given for this phenomenon. 相似文献
15.
Othman AM El-Houseini ME El-Sofy MS Aboul-Enein HY 《Analytical and bioanalytical chemistry》2011,400(3):787-795
The activity of the α-l-fucosidase (AFU) enzyme represents an excellent test for diagnosis of hepatocellular carcinoma (HCC) and fucosidosis recognized
in inborn disorder of metabolism and increases the sensitivity of detection to 95.5% in patients with HCC. Therefore, the
determination of the activity of AFU enzyme is very important and can be used as a screening tool for the early diagnosis
of tumors for HCC patients. A simple, accurate, and sensitive potentiometric method was developed for measuring the activity
of AFU. The method was based upon measuring the concentration of 2-chloro-4-nitrophenol (2-chloro-4-NP) using a 2-chloro-4-NP-rhodamine
B ion pair in a PVC membrane sensor. The electrode shows a linear, reproducible, and stable potentiometric response with an
anionic Nernstian slope of −51.13 ± 0.6 mV/decade over a wide range of concentrations 10−5–10−2 M and a detection limit of 1.0 × 10−6 M of 2-chloro-4-NP. The membrane exhibits a fast response time of 30 s, over a pH range of 4.0–6.5. The selectivity coefficients
indicate excellent selectivity for 2-chloro-4-NP over a number of interfering species, e.g., chloride, nitrate, sulfate, chromate
urea, albumin, glucose, uric acid, and total protein. The prepared sensor has been used successfully for the determination
of 2-chloro-4-NP produced from the hydrolysis of 2-chloro-4-NP-α-l-fucopyranoside substrate. It was also applied for the determination α-l-fucosidase enzyme of 33 serum samples of healthy subjects and patients. The average recoveries ± RSD for the healthy subjects,
cirrhosis of chronic hepatitis C and B, and HCC serum samples were 102.6 ± 1.01%, 101.5 ± 0.95%, and 100.1 ± 1.1%, respectively.
The results obtained are in good agreement with those obtained by standard methods. 相似文献
16.
The influence of ethanol on fermentation by Pachysolen tannophilus was studied. When xylose utilization rate was 80%, ethanol concentration began to decline. Fermentation of P. tannophilus was affected by ethanol addition in the beginning of fermentation; average xylose consumption rate was 0.065 g·l−1·h−1, and maximum specific growth rate was 0.07 h−1 at 28 g·l−1 ethanol, comparing with the average xylose consumption rate of 0.38 g·l−1·h−1 and maximum specific growth rate of 0.14 h−1 in fermentation with no ethanol addition; P. tannophilus stopped growth at 40 g·l−1 ethanol. When the initial ethanol concentration was 30 g·l−1, the addition of glucose in xylose media made the growth of P. tannophilus better, and the most favorable glucose concentration was 15 g·l−1 with the highest biomass of 1.51 g·l−1 as compared with that of 0.95 g·l−1 in pure xylose media. 相似文献
17.
Wanli Liu Pengjun Shi Qiang Chen Peilong Yang Guozeng Wang Yaru Wang Huiying Luo Bin Yao 《Applied biochemistry and biotechnology》2010,162(1):1-12
A xylanase-encoding gene, xyn11F63, was isolated from Penicillium sp. F63 CGMCC1669 using degenerated polymerase chain reaction (PCR) and thermal asymmetric interlaced (TAIL)-PCR techniques.
The full-length chromosomal gene consists of 724 bp, including a 73-bp intron, and encodes a 217 amino acid polypeptide. The
deduced amino acid sequence of xyn11F63 shows the highest identity of 70% to the xylanase from Penicillium sp. strain 40, which belongs to glycosyl hydrolases family 11. The gene was overexpressed in Pichia pastoris, and its activity in the culture medium reached 516 U ml−1. After purification to electrophoretic homogeneity, the enzyme showed maximal activity at pH 4.5 and 40°C, was stable at
acidic buffers of pH 4.5–9.0, and was resistant to proteases (proteinase K, trypsin, subtilisin A, and α-chymotrypsin). The
specific activity, K
m, and V
max for oat spelt xylan substrate was 7,988 U mg−1, 22.2 mg ml−1, and 15,105.7 μmol min−1 mg−1, respectively. These properties make XYN11F63 a potential economical candidate for use in feed and food industrial applications. 相似文献
18.
Wanwisa Moon-ai Ploypat Niyomploy Ruethairat Boonsombat Polkit Sangvanich Aphichart Karnchanatat 《Applied biochemistry and biotechnology》2012,166(8):2138-2155
Superoxide dismutase (SOD, EC 1.15.1.1) is a metalloenzyme or antioxidant enzyme that catalyzes the disproportionation of
the harmful superoxide anionic radical to hydrogen peroxide and molecular oxygen. Due to its antioxidative effects, SOD has
long been applied in medicinal treatment, cosmetic, and other chemical industries. Fifteen Zingiberaceae plants were tested
for SOD activity in their rhizome extracts. The crude homogenate and ammonium sulfate cut fraction of Curcuma aeruginosa were found to contain a significant level of SOD activity. The SOD enzyme was enriched 16.7-fold by sequential ammonium sulfate
precipitation, diethylaminoethyl cellulose ion exchange, and Superdex 75 gel filtration column chromatography. An overall
SOD yield of 2.51 % with a specific activity of 812.20 U/mg was obtained. The enriched SOD had an apparent MW of 31.5 kDa,
as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and a pH and temperature optima of 4.0 and 50 °C.
With nitroblue tetrazolium and riboflavin as substrates, the K
m values were 57.31 ± 0.012 and 1.51 ± 0.014 M, respectively, with corresponding V
max values of 333.7 ± 0.034 and 254.1 ± 0.022 μmol min−1 mg protein−1. This SOD likely belongs to the Fe- or Mn-SOD category due to the fact that it was insensitive to potassium cyanide or hydrogen
peroxide inhibition, but was potentially weakly stimulated by hydrogen peroxide, and stimulated by Mn2+and Fe2+ ions. Moreover, this purified SOD also exhibited inhibitory effects on lipopolysaccharide-induced nitric oxide production
in cultured mouse macrophage cell RAW 264.7 in a dose-dependent manner (IC50 = 14.36 ± 0.15 μg protein/ml). 相似文献
19.
Hossein Amani Mohammad Reza Mehrnia Mohammad Hossein Sarrafzadeh Manouchehr Haghighi Mohammad Reza Soudi 《Applied biochemistry and biotechnology》2010,162(2):510-523
There is a lack of fundamental knowledge about the scale up of biosurfactant production. In order to develop suitable technology
of commercialization, carrying out tests in shake flasks and bioreactors was essential. A reactor with integrated foam collector
was designed for biosurfactant production using Bacillus subtilis isolated from agricultural soil. The yield of biosurfactant on biomass (Y
p/x), biosurfactant on sucrose (Y
p/s), and the volumetric production rate (Y) for shake flask were obtained about 0.45 g g−1, 0.18 g g−1, and 0.03 g l−1 h−1, respectively. The best condition for bioreactor was 300 rpm and 1.5 vvm, giving Y
x/s, Y
p/x, Y
p/s, and Y of 0.42 g g−1, 0.595 g g−1, 0.25 g g−1, and 0.057 g l−1 h−1, respectively. The biosurfactant maximum production, 2.5 g l−1, was reached in 44 h of growth, which was 28% better than the shake flask. The obtained volumetric oxygen transfer coefficient
(K
L
a) values at optimum conditions in the shake flask and the bioreactor were found to be around 0.01 and 0.0117 s−1, respectively. Comparison of K
L
a values at optimum conditions shows that biosurfactant production scaling up from shake flask to bioreactor can be done with
K
L
a as scale up criterion very accurately. Nearly 8% of original oil in place was recovered using this biosurfactant after water
flooding in the sand pack. 相似文献
20.
A phosphite dehydrogenase gene (ptdhK) consisting of 1,011-bp nucleotides which encoding a peptide of 336 amino acid residues was cloned from Pseudomonas sp. K. gene ptdhK was expressed in Escherichia coli BL21 (DE3) and the corresponding recombinant enzyme was purified by metal affinity chromatography. The recombinant protein
is a homodimer with a monomeric molecular mass of 37.2 kDa. The specific activity of PTDH-K was 3.49 U mg−1 at 25 °C. The recombinant PTDH-K exhibited maximum activity at pH 3.0 and at 40 °C and displayed high stability within a
wide range of pHs (5.0 to 10.5). PTDH-K had a high affinity to its natural substrates, with K
m values for sodium phosphite and NAD of 0.475 ± 0.073 and 0.022 ± 0.007 mM, respectively. The activity of PTDH-K was enhanced
by Na+, NH4+, Mg2+, Fe2+, Fe3+, Co2+, and EDTA, and PTDH-K exhibited different tolerance to various organic solvents. 相似文献