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1.
The kinetic parameters Km and Vmax for urea uptake by Melosira italica were determined at 160 μeinsteins m−2 s−1 and in the dark. The transport systems showed an affinity for the substrate and a storing capacity in the dark (Km = 65.07 μM; Vmax = 2.18 nmoles 105 cells −1 h−1) greater than under 160 μE m−2 s −1 (Km = 111.2 μM; Vmax = 1.11 nmoles 105 cells−1 h−1). Similarly, a reduction in consumption rate of urea under increasing photon flux densities was observed. The use of an inhibitor
(potassium cyanide) indicated that the uptake process requires metabolic energy. That urea transport is more important in
darkness, may constitute a survival strategy in which this compound is utilized by cells mainly during heterotrophic growth. 相似文献
2.
Current enzymatic methods for the analysis of glycated proteins use flavoenzymes that catalyze the oxidative deglycation of
fructosyl peptides, designated as fructosyl peptidyl oxidases (FPOXs). However, as FPOXs are oxidases, the signals derived
from electron mediator-type electrochemical monitoring based on them are affected by dissolved O2. Improvement of dye-mediated dehydrogenase activity of FPOXs and its application to enzyme electrode construction were therefore
undertaken. Saturation mutagenesis study on Asn56 of FPOX from Phaeosphaeria nodorum, produced mutants with marked decreases in the catalytic ability to employ O2 as the electron acceptor, while showing higher dye-mediated dehydrogenase activity employing artificial electron acceptors
than the parental enzyme. Thus constructed virtually fructosyl peptide dehydrogenase, Asn56Ala, was then applied to produce
an enzyme electrode for the measurement of fructosyl-α
N-valyl-histidine (f-αVal-His), the protease-digested product of HbA1c. The enzyme electrode could measure f-αVal-His in the physiological target range in air. 相似文献
3.
M. Vanko D. Rauová L. Bezáková I. Holková F. Bilka M. Cupáková 《Biologia Plantarum》2012,56(1):105-110
Lipoxygenase (LOX) from opium poppy (Papaver somniferum L.) chloroplasts was isolated and 126.1-fold purified to electrophoretic homogeneity by combination of ion-exchange chromatography
on HA-Ultragel column and affinity chromatography on a linoleyl-aminopropyl agarose column. The relative molecular mass of the LOX determined
by SDS-PAGE was 92 kDa. Kinetic properties of purified LOX were determined in spectrophotometric assay by using of linoleic
acid (KM = 1.78 mM and Vmax = 11.4 μmol mg−1 min−1) and linolenic acid (KM = 1.27 mM and Vmax = 10.2 μmol mg−1 min−1). The optimum pH was 6.0 for both linoleic and linolenic acid dioxygenation catalyzed by LOX. HPLC analysis of the products
revealed a dual positional specificity of linoleic acid dioxygenation at pH 6.0 with ratio of 9- and 13-hydroperoxide products
being about 1:1. The activity of purified LOX was stimulated by Mg2+ and Ca2+. 相似文献
4.
To overcome the extracellular salt stress, Methanohalophilus portucalensis FDF1T synthesizes the compatible solute betaine through the methylation of glycine, sarcosine, and N,N-dimethylglycine. S-adenosylmethionine (AdoMet) is the methyl donor. The enzyme sarcosine dimethylglycine N-methyltransferase (SDMT) of M. portucalensis, that catalyzes the formation of N,N-dimethylglycine and glycine betaine, has been purified and characterized. SDMT, a monomer of 33 kDa with a pI at 5.03, has
a narrow substrate specificity limited to using only sarcosine and dimethylglycine as substrates for the methyl transferase
reaction. The K
m values for sarcosine and AdoMet were 2.29 and 0.21 mM, respectively, with a V
max of 0.83 μmol/mg-min (k
cat value of 0.44 s−1). The K
m values for dimethylglycine and AdoMet were 3.76 and 0.59 mM, respectively, with a V
max of 4.88 μmol/mg-min (k
cat of 2.68 s−1). A high concentration of the end product betaine (2.0 M) did not affect the SMT activity, but it slightly inhibited the
DMT activity. Both activities were also not affected by potassium or sodium ions in concentrations of 200–1,000 mM. We compared
this novel archaeal SDMT enzyme to other similar bacterial transferases as well as to the glycine sarcosine dimethylglycine
methyltransferase found also in M. portucalensis. 相似文献
5.
Basaran Pervin Basaran Nese Hang Yong D. 《World journal of microbiology & biotechnology》2000,16(6):545-550
Pichia stipitis strain NRRL Y-11,543 was mutagenized with N-methyl-N′-nitro-N-nitrosoguanidine (NTG) to improve xylanolytic activity. A total of 20,000 mutants were screened for xylanase overproduction
by observing the clear zones around the colonies on remazol-briliant-blue-xylan (RBB-xylan)-containing agar. Of 94 mutants
isolated 11 of them were found to have enhanced xylanase activity compared to the parental strain. The most active mutant
NP54376 had superior properties to the wild type which included: double the enzyme activity of wild type, a shorter generation
time of 2.22 h compared to 3.13 h when grown on xylan, and an enhanced growth and yield of xylanase when low levels of xylose
were added to the medium. Zymogram analysis of the crude enzyme preparations from both NP54376 and the wild type by isoelectric
focusing showed multiple bands ranging between pI 4.2 and 7.4. No significant difference was observed in the K
m and V
max values of the parental strain and NP54376. K
m and V
max values of xylanase for birchwood xylan were 4.2 mg ml−1 and 0.08 μmol min−1 mg−1 of protein, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
Purification and characterization of an ADP-dependent phosphofructokinase from Thermococcus zilligii 总被引:1,自引:0,他引:1
R. S. Ronimus Jurre Koning H. W. Morgan 《Extremophiles : life under extreme conditions》1999,3(2):121-129
The ADP-dependent phosphofructokinase (PFK) from Thermococcus zilligii has been purified 950 fold; it had a specific activity of 190 U mg−1. The enzyme required Mg2+ ions for optimal activity and was specific for ADP. The forward reaction kinetics were hyperbolic for both cosubstrates (pH
optimum of 6.4), and the apparent K
m values for ADP and fructose-6-phosphate were 0.6 mM (apparent V
max of 243 U mg−1) and 1.47 mM (apparent V
max of 197 U mg−1), respectively. Significantly, the enzyme is indicated to be nonallosteric but was slightly activated by some monovalent
cations including Na+ and K+. The protein had a subunit size of 42.2 kDa and an estimated native molecular weight of 66 kDa (gel filtration). Maximal
reaction rates for the reverse reaction were attained at pH 7.5–8.0, and the apparent K
m values for fructose-1,6-bisphosphate and AMP were 0.56 mM (apparent V
max of 2.9 U mg−1) and 12.5 mM, respectively. The biochemical characteristics of this unique ADP-dependent enzymatic activity are compared
to ATP and pyrophosphate-dependent phosphofructokinases.
Received: August 14, 1998 / Accepted: December 2, 1998 相似文献
7.
M.I. Rajoka Khalil-ur- Rehman Tehmina Tabish M.A. Zia 《World journal of microbiology & biotechnology》2006,22(3):289-291
Purified uricase from a caprine kidney, possessed K
m
and V
max values of 1.1 mg ml−1 and 3512 IU (mg protein)−1 for uric acid hydrolysis, respectively. The optimum temperature and pH for catalytic activity were 40 °C and 8.5, respectively.
The activation energy for formation of ES complex was 13.6 kJ mol−1. Enthalpy (ΔH*), entropy of activation (ΔS*) and Gibbs free energy demand of uricase inactivation were 62.8 kJ mol−1, −102 J mol−1 K−1 and 104.3 kJ mol−1, respectively. Gibbs free enrgy demand for substrate binding and transition state stabilization were also determined which
were comparable with those for themostable enzymes. 相似文献
8.
Summary Cells ofCandida shehatae repressed by growth in glucose- or D-xylose-medium produced a facilitated diffusion system that transported glucose (K
s±2 mM,V
max±2.3 mmoles g−1 h−1),d-xylose (K
s±125 mM,V
max±22.5 mmoles g−1 h−1) and D-mannose, but neither D-galactose norl-arabinose.
Cells derepressed by starvation formed several sugar-proton symports. One proton symport accumulated 3-0-methylglucose about
400-fold and transported glucose (K
s±0.12 mM,V
max ± 3.2 mmoles g−1 h−1) andd-mannose, a second proton symport transportedd-xylose (K
s± 1.0 mM,V
max 1.4 mmoles g−1 h−1) andd-galactose, whilel-arabinose apparently used a third proton symport. The stoicheiometry was one proton for each molecule of glucose or D-xylose
transported. Substrates of one sugar proton symport inhibited non-competitively the transport of substrates of the other symports.
Starvation, while inducing the sugar-proton symports, silenced the facilitated diffusion system with respect to glucose transport
but not with respect to the transport of D-xylose, facilitated diffusion functioning simultaneously with thed-xylose-proton symport. 相似文献
9.
Isochorismate hydroxymutase (i.e. isochorismate synthase, EC 5.4.99.6) was purified from an anthraquinone-producing cell-suspension
culture of Galium mollugo L. Although attempts to stabilize the labile enzyme met with little success, a substantial increase in enzyme activity was
observed in the presence of glycine betaine (500 mM). Column chromatography on solid supports other than diethylaminoethyl
(DEAE)-Sephacel, Phenylsepharose Cl-4B or Cibacron Blue 3G-A did not give active enzyme preparations. In spite of these drawbacks
the enzyme was purified 573-fold. Enzyme activity depended strictly on the presence of Mg2+. Kinetic data for chorismate in the forward reaction (K
m = 807 μM, V
max = 6.2 pkat · mg−1) and for isochorismate in the reverse reaction (K
m = 675 μM, V
max = 5.9 pkat · mg−1) were determined.
Received: 18 November 1996 / Accepted: 28 December 1996 相似文献
10.
Summary Putrescine-oxidase activity was found in fetal bovine serum (FBS) with a pH optimum of 8.0 and in adult bovine serum (ABS)
with a pH optimum of 9.8. The crude FBS enzyme had a KM for putrescine of 2.58×10−6
m and a Vmax of 0.53 nmol per hr per 50 μl serum. Aminoguanidine competitively inhibited the enzyme with a KI of 1.8×10−8
m. Spermidine and spermine proved competitive inhibitors of putrescine for both the FBS and the crude ABS putrescine oxidases.
The Vmax for the ABS putrescine oxidase was 2.10 nmol per hr per 50 μl serum, and the KM for putrescine, 50.3×10−6
m. The K1 of the ABS putrescine oxidase for aminoguanidine was 41×10−6
m. On the basis of both the KM and KI values, the adult serum enzyme, at its optimal pH of 9.8, bound spermidine and spermine more avidly than the smaller putrescine
and aminoguanidine; whereas the FBS enzyme, at pH 8.0, bound aminoguanidine and putrescine more tightly than the larger polyamines.
Each of the enzymes retained over 80% of its activity after heating at 56°C for 30 min. Applications of these data to the
study of polyamines in tissue culture and to the purification of diamine oxidases are discussed.
This work was supported in part by a grant from the Cystic Fibrosis Foundation. 相似文献
11.
Lipase-catalyzed synthesis of isoamyl acetate in hexane at 10–250 MPa at 80°C and 1–100 MPa at 40°C resulted in activation
volumes of −12.9 ± 1.7 and −21.6 ± 2.9 cm3 mol−1, respectively. Increasing pressure from 10 to 200 MPa resulted in approximately 10-fold increase in V
max at both 40 and 80°C. Pressure increased the K
m from 2.4 ± 0.004 to 38 ± 0.78 mM at 40°C. In contrast, at 80°C the pressure did not affect the K
m. 相似文献
12.
Corynebacterium glutamicum took up glutamine by a sodium-dependent secondary transport system. Both the membrane potential and the sodium gradient were
driving forces. Glutamine uptake showed Michaelis-Menten kinetics, with aK
m of 36 μM and aV
max of 12.5 nmol min−1 (mg dry weight)−1 at pH 7. Despite a pH optimum in the alkaline range around pH 9, it was shown that uncharged glutamine is the transported
species. The affinity for the cotransported sodium was relatively low; an apparentK
m of 1.4 mM was determined. Among various substrates tested, only asparagine, when added in 50-fold excess, led to an inhibition
of glutamine transport. It was concluded that glutamine uptake occurs via a specific transport system in symport with at least
one sodium ion. 相似文献
13.
S A Shaikh J M Khire M I Khan 《Journal of industrial microbiology & biotechnology》1997,19(4):239-245
A thermostable β-galactosidase was produced extracellularly by a thermophilic Rhizomucor sp, with maximum enzyme activity (0.21 U mg−1) after 4 days under submerged fermentation condition (SmF). Solid state fermentation (SSF) resulted in a nine-fold increase
in enzyme activity (2.04 U mg−1). The temperature range for production of the enzyme was 38–55°C with maximum activity at 45°C. The optimum pH and temperature
for the partially purified enzyme was 4.5 and 60°C, respectively. The enzyme retained its original activity on incubation
at 60°C up to 1 h. Divalent cations like Co2+, Mn2+, Fe2+ and Zn2+ had strong inhibitory effects on the enzyme activity. The K
m and V
max for p-nitrophenyl-β- D-galactopyranoside and o-nitrophenyl-β - D-galactopyranoside were 0.39 mM, 0.785 mM and 232.1 mmol min−1 mg−1 respectively. The K
m and V
max for the natural substrate lactose were 66.66 μM and 0.20 μ mol min−1 mg−1.
Received 10 March 1997/ Accepted in revised form 17 July 1997 相似文献
14.
In frog red blood cells, K-Cl cotransport (i.e., the difference between ouabain-resistant K fluxes in Cl and NO3) has been shown to mediate a large fraction of the total K+ transport. In the present study, Cl−-dependent and Cl−-independent K+ fluxes via frog erythrocyte membranes were investigated as a function of external and internal K+ ([K+]
e
and [K+]
i
) concentration. The dependence of ouabain-resistant Cl−-dependent K+ (86Rb) influx on [K+]
e
over the range 0–20 mm fitted the Michaelis-Menten equation, with an apparent affinity (K
m
) of 8.2 ± 1.3 mm and maximal velocity (V
max
) of 10.4 ± 1.6 mmol/l cells/hr under isotonic conditions. Hypotonic stimulation of the Cl−-dependent K+ influx increased both K
m
(12.8 ± 1.7 mm, P < 0.05) and V
max
(20.2 ± 2.9 mmol/l/hr, P < 0.001). Raising [K+]
e
above 20 mm in isotonic media significantly reduced the Cl−-dependent K+ influx due to a reciprocal decrease of the external Na+ ([Na+]
e
) concentration below 50 mm. Replacing [Na+]
e
by NMDG+ markedly decreased V
max
(3.2 ± 0.7 mmol/l/hr, P < 0.001) and increased K
m
(15.7 ± 2.1 mm, P < 0.03) of Cl−-dependent K+ influx. Moreover, NMDG+ Cl substitution for NaCl in isotonic and hypotonic media containing 10 mm RbCl significantly reduced both Rb+ uptake and K+ loss from red cells. Cell swelling did not affect the Na+-dependent changes in Rb+ uptake and K+ loss. In a nominally K+(Rb+)-free medium, net K+ loss was reduced after lowering [Na+]
e
below 50 mm. These results indicate that over 50 mm [Na+]
e
is required for complete activation of the K-Cl cotransporter. In nystatin-pretreated cells with various intracellular K+, Cl−-dependent K+ loss in K+-free media was a linear function of [K+]
i
, with a rate constant of 0.11 ± 0.01 and 0.18 ± 0.008 hr−1 (P < 0.001) in isotonic and hypotonic media, respectively. Thus K-Cl cotransport in frog erythrocytes exhibits a strong asymmetry
with respect to transported K+ ions. The residual, ouabain-resistant K+ fluxes in NO3 were only 5–10% of the total and were well fitted to linear regressions. The rate constants for the residual influxes were
not different from those for K+ effluxes in isotonic (∼0.014 hr−1) and hypotonic (∼0.022 hr−1) media, but cell swelling resulted in a significant increase in the rate constants.
Received: 19 November 1998/Revised: 23 August 1999 相似文献
15.
Björn Lindman 《Antonie van Leeuwenhoek》1981,47(4):297-306
The initial rate ofd-glucosamine uptake by the non-halotolerant yeastSaccharomyces cerevisiae was approximately halved as the apparent half saturation constant (Km) and the apparent maximum velocity (Vmax) changed from 6.6mm to 16.4mm and from 22 μmol · g−1 · min−1 to 16 μmol · g−1 · min−1, respectively, when the salinity in the medium was increased from zerom to 0.68m NaCl. Corresponding changes in a high affinity transport system in the halotolerant yeastDebaryomyces hansenii were from 1.1mm to 4.6mm and from 3.1 μmol · g−1 · min−1 to 4.5 μmol · g−1 · min−1, implying a practically unchanged transport capacity. In 2.7m NaCl, Km and Vmax in this system were 24.5mm and 1.1 μmol · g−1 · min−1, respectively, representing a marked decrease in transport capability. Nevertheless, the degree of affinity in this extreme
salinity must still be regarded as noteworthy. In addition to the high affinity transport system inD. hansenii, a low affinity system, presumably without relevance ind-glucosamine transport, was observed. 相似文献
16.
To study vacuolar chloride (Cl−) transport in the halophilic plant Mesembryanthemum crystallinum L., Cl− uptake into isolated tonoplast vesicles was measured using the Cl−-sensitive fluorescent dye lucigenin (N,N′-dimethyl-9,9′-bisacridinium dinitrate). Lucigenin was used at excitation and emission wavelengths of 433 nm and 506 nm,
respectively, and showed a high sensitivity towards Cl−, with a Stern-Volmer constant of 173 m
−1 in standard assay buffer. While lucigenin fluorescence was strongly quenched by all halides, it was only weakly quenched,
if at all, by other anions. However, the fluorescence intensity and Cl−-sensitivity of lucigenin was shown to be strongly affected by alkaline pH and was dependent on the conjugate base used as
the buffering ion. Chloride transport into tonoplast vesicles of M. crystallinum loaded with 10 mm lucigenin showed saturation-type kinetics with an apparent K
m
of 17.2 mm and a V
max
of 4.8 mm min−1. Vacuolar Cl− transport was not affected by sulfate, malate, or nitrate. In the presence of 250 μm
p-chloromercuribenzene sulfonate, a known anion-transport inhibitor, vacuolar Cl− transport was actually significantly increased by 24%. To determine absolute fluxes of Cl− using this method, the average surface to volume ratio of the tonoplast vesicles was measured by electron microscopy to be
1.13 × 107 m−1. After correcting for a 4.4-fold lower apparent Stern-Volmer constant for intravesicular lucigenin, a maximum rate of Cl− transport of 31 nmol m−2 sec−1 was calculated, in good agreement with values obtained for the plant vacuolar membrane using other techniques.
Received: 18 February 2000/Revised: 30 June 2000 相似文献
17.
Seungsu Kim Stefano Ferri Wakako Tsugawa Kazushige Mori Koji Sode 《Biotechnology and bioengineering》2010,106(3):358-366
The measurement of glycated hemoglobin A1c (HbA1c) has important implications for diagnosis of diabetes and assessment of treatment effectiveness. We proposed specific sequence motifs to identify enzymes that oxidize glycated compounds from genome database searches. The gene encoding a putative fructosyl amino acid oxidase was found in the Phaeosphaeria nodorum SN15 genome and successfully expressed in Escherichia coli. The recombinant protein (XP_001798711) was confirmed to be a novel fructosyl peptide oxidase (FPOX) with high specificity for α‐glycated compounds, such as HbA1c model compounds fructosyl‐αN‐valine (f‐αVal) and fructosyl‐αN‐valyl‐histidine (f‐αVal‐His). Unlike previously reported FPOXs, the P. nodorum FPOX has a Km value for f‐αVal‐His (0.185 mM) that is considerably lower than that for f‐αVal (0.458 mM). Based on amino acid sequence alignment, three dimensional structural modeling, and site‐directed mutagenesis, Gly60 was found to be a determining residue for the activity towards f‐αVal‐His. A flexible surface loop region was also found to likely play an important role in accepting f‐αVal‐His. Biotechnol. Bioeng. 2010; 106: 358–366. © 2010 Wiley Periodicals, Inc. 相似文献
18.
d-Aspartate (d-Asp) uptake by suspensions of cerebral rat brain astrocytes (RBA) maintained in long-term culture was studied as a means
of characterizing function and regulation of Glutamate/Aspartate (Glu/Asp) transporter isoforms in the cells. d-Asp influx is Na+-dependent with K
m
= 5 μm and V
max= 0.7 nmoles · min−1· mg protein−1. Influx is sigmoidal as f[Na+] with Na+
K
m
∼ 12 μm and Hill coefficient of 1.9. The cells establish steady-state d-Asp gradients >3,000-fold. Phorbol ester (PMA) enhances uptake, and gradients near 6,000-fold are achieved due to a 2-fold
increase in V
max, with no change in K
m
. At initial [d-Asp] = 10 μm, RBA take up more than 90% of total d-Asp, and extracellular levels are reduced to levels below 1 μm. Ionophores that dissipate the ΔμNa+ inhibit gradient formation. Genistein (GEN, 100 μm), a PTK inhibitor, causes a 40% decrease in d-Asp. Inactive analogs of PMA (4α-PMA) and GEN (daidzein) have no detectable effect, although the stimulatory PMA response
still occurs when GEN is present. Further specificity of action is indicated by the fact that PMA has no effect on Na+-coupled ALA uptake, but GEN is stimulatory. d-Asp uptake is strongly inhibited by serine-O-sulfate (S-O-S), threohydroxy-aspartate (THA), l-Asp, and l-Glu, but not by d-Glu, kainic acid (KA), or dihydrokainate (DHK), an inhibition pattern characteristic of GLAST and EAAC1 transporter isoforms.
mRNA for both isoforms was detected by RT-PCR, and Western blotting with appropriate antibodies shows that both proteins are
expressed in these cells.
Received: 11 January 2001/Revised: 26 March 2001 相似文献
19.
Dihydroorotase was purified to homogeneity fromPseudomonas putida. The relative molecular mass of the native enzyme was 82 kDa and the enzyme consisted of two identical subunits with a relative
molecular mass of 41 kDa. The enzyme only hydrolyzed dihydro-l-orotate and its methyl ester, and the reactions were reversible. The apparentK
m andV
max values for dihydro-l-orotate hydrolysis (at pH 7.4) were 0.081 mM and 18 μmol min−1 mg−1, respectively; and those forN-carbamoyl-dl-aspartate (at pH 6.0) were 2.2 mM and 68 μmol min−1 mg−1, respectively. The enzyme was inhibited by metal ion chelators and activated by Zn2+. However, excessive Zn2+ was inhibitory. The enzyme was inhibited by sulfhydryl reagents, and competitively inhibited byN-carbamoylamino acids such asN-carbamoylglycine, with aK
i value of 2.7 mM. The enzyme was also inhibited noncompetitively by pyrimidine-metabolism intermediates such as dihydrouracil
and orotate, with aK
i value of 3.4 and 0.75 mM, respectively, suggesting that the enzyme activity is regulated by pyrimidine-metabolism intermediates
and that dihydroorotase plays a role in the control of pyrimidine biosynthesis. 相似文献
20.
Clostridium acetobutylicum P262 cells that were
growing on lactate and acetate had an NAD-independent lactate dehydrogenase
(iLDH) activity of 200 nmol mg protein−1 min−1.
Ammonium sulfate precipitation and DEAE cellulose caused a 35-fold
purification. Gel filtration indicated that the iLDH had a molecular weight
of approximately 55 kDa, but two bands were always observed. Phenyl sepharose
could not separate the two proteins, and hydroxyapatite caused a complete
loss of activity. The semi-purified iLDH had a Vmax of 13,000 nmol
mg protein−1 min−1 and a K
m
value of 3.5 mM for D-lactate. The Vmax and K
m
values for L-lactate were 300 nmol mg protein−1
min−1 and 0.7 mM. The iLDH had a pH optimum of 7.5, was not
activated by fructose-1,6-bisphosphate (FDP), and could be coupled to either
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) or
dichlorophenol-indophenol (DCPIP), but not methyl viologen (MV) or benzyl
viologen (BV). The iLDH did not have strong absorbance between 500 and 300
nm, and trichloroacetic acid or acid ammonium sulfate extracts had virtually
no fluorescence at 450 nm. The crude extracts also had MTT-linked butyryl-CoA
dehydrogenase activity (60 nmol mg protein−1
min−1). The NAD-independent butyryl-CoA dehydrogenase eluted
from DEAE-cellulose as two fractions. The yellow fraction was extremely
unstable, but the green fraction could be stored for short periods of time at
5°C. The green-colored butyryl-CoA dehydrogenase had strong absorption at
450 nm, and gel filtration indicated that it had a molecular weight of 90
kDa. The NAD-independent butyryl-CoA dehydrogenase could be coupled to MTT,
DCPIP, or MV, but not BV. Because the NAD-independent lactate and butyryl-CoA
dehydrogenase could both be linked to low potential carriers, these two
enzymes may function as oxidation-reduction system in vivo.
Received: 24 July 1996 / Accepted: 10 September 1996 相似文献