共查询到20条相似文献,搜索用时 453 毫秒
1.
It was found that low oxytetracycline (OTC) concentrations inhibited malic dehydrogenase (MDH) and lactic dehydrogenase (LDH)
inStaphylococcus aureus andEscherichia coli (1–5 μg/ml for MDH and 10 μg/ml for LDH). Inhibition of these enzymes occurred almost instantaneously and could be demonstrated
after 3–4 minutes. No MDH activity was found in OTC-resistant variants of these microorganisms, but LDH activity was not lowered.
The inhibitory effect of OTC is specific for bacterial MDH and LDH. The same enzymes of mammalian origin are not inhibitedin vitro even by high OTC concentrations (100 μg/ml). 相似文献
2.
The aldo-keto reductase enzymes comprise a functionally diverse gene family which catalyze the NADPH-dependant reduction
of a variety of carbonyl compounds. The protein sequences of 45 members of this family were aligned and phylogenetic trees
were deduced from this alignment using the neighbor-joining and Fitch algorithms. The branching order of these trees indicates
that the vertebrate enzymes cluster in three groups, which have a monophyletic origin distinct from the bacterial, plant,
and invertebrate enzymes. A high level of conservation was observed between the vertebrate hydroxysteroid dehydrogenase enzymes,
prostaglandin F synthase, and ρ-crystallin of Xenopus laevis. We infer from the phylogenetic analysis that prostaglandin F synthase may represent a recent recruit to the eicosanoid biosynthetic
pathway from the hydroxysteroid dehydrogenase pathway and furthermore that, in the context of gene recruitment, Xenopus laevisρ-crystallin may represent a shared gene.
Received: 26 August 1996 / Accepted: 5 June 1997 相似文献
3.
The present study was undertaken to examine the influence of toxic levels of Ni and Al, on the activities of key nitrogen
assimilatory enzymes in roots and shoots of growing rice seedlings. When seedlings of two inbred rice (Oryza sativa L.) cvs. Malviya-36 and Pant-12, sensitive to both Ni and Al, were raised in sand cultures containing 200 and 400 μM NiSO4 or 80 and 160 μM Al2(SO4)3, a marked inhibition in the activities of NO3
− assimilatory enzymes NR and GS was observed in roots as well as shoots during a 5–20 day growth period. Both Ni and Al treatments,
in growth medium, stimulated the activity of aminating glutamate dehydrogenase (NADH-GDH) whereas the activity of deaminating
GDH (NAD+-GDH) decreased under metal toxicities. The activities of the aminotransferases studied; alanine aminotransferase (AlaAT)
and aspartate amino transferase (AspAT) increased due to Ni and Al treatments. Results suggest that both Ni and Al treatments
impair N assimilation in rice seedlings by inhibiting the activities of NR and GS and that GDH appears to play a role in assimilation
of NH4
+ in metal stress conditions. Further, higher activity of aminotransferases in metal stressed seedlings might be helpful in
meeting higher demand of amino acids under stressed conditions. 相似文献
4.
Tanner JJ 《Amino acids》2008,35(4):719-730
The proline catabolic enzymes proline dehydrogenase and Δ1-pyrroline-5-carboxylate dehydrogenase catalyze the 4-electron oxidation of proline to glutamate. These enzymes play important
roles in cellular redox control, superoxide generation, apoptosis and cancer. In some bacteria, the two enzymes are fused
into the bifunctional enzyme, proline utilization A. Here we review the three-dimensional structural information that is currently
available for proline catabolic enzymes. Crystal structures have been determined for bacterial monofunctional proline dehydrogenase
and Δ1-pyrroline-5-carboxylate dehydrogenase, as well as the proline dehydrogenase and DNA-binding domains of proline utilization
A. Some of the functional insights provided by analyses of these structures are discussed, including substrate recognition,
catalytic mechanism, biochemical basis of inherited proline catabolic disorders and DNA recognition by proline utilization
A. 相似文献
5.
α-Crystallin is known to act as a molecular chaperone by preventing the aggregation of partially unfolded substrate proteins.
It is also known to assist the refolding of a number of denatured enzymes, but the activity yield is often less than 20%.
In this paper, we have tried to tune the refolding ability of α-crystallin in vitro by optimizing various external parameters. We wanted to find out the best possible condition under which it can exhibit maximum refolding capacity. We found that under
suitable condition in vitro α-crystallin can refold denatured malate dehydrogenase, carbonic anhydrase and lactate dehydrogenase to recover more than
40% activity. We also measured the effect of several external factors such as nucleotides, osmolytes, electrolytes, temperature
etc. on the in vitro α-crystallin mediated reactivation of above stated enzymes. We found that nucleotides and electrolytes had little effect
on the refolding ability of α-crystallin. However, in presence of different osmolytes, we found that its ability to reactivate
denatured substrate proteins enhanced significantly. Refolding in presence of pre-incubated α-crystallin reveals that hydrophobicity
had stronger influence on the refolding capacity of α-crystallin than its oligomeric size. 相似文献
6.
Assembly of graphene oxide‐formate dehydrogenase composites by nickel‐coordination with enhanced stability and reusability 下载免费PDF全文
Featuring unique planar structure, large surface area and biocompatibility, graphene oxide (GO) has been widely taken as an ideal scaffold for the immobilization of various enzymes. In this regard, nickel‐coordinated graphene oxide composites (GO‐Ni) were prepared as novel supporters for the immobilization of formate dehydrogenase. The catalytic activity, stability and morphology were studied. Compared with GO, the enzyme loading capacity of GO‐Ni was enhanced by 5.2‐fold, besides the immobilized enzyme GO‐Ni‐FDH exhibited better thermostability, storage stability and reuse stability than GO‐FDH. GO‐Ni‐FDH retained 40.9% of its initial activity after 3 h at 60°C, and retained 31.4% of its initial relative activity after 20 days’ storage at 4°C. After eight times usages, GO‐Ni‐FDH maintained 63.8% of its initial activity. Mechanism insights of the multiple interactions of enzyme with the GO‐Ni were studied, considering coordination bonds, hydrogen bonds, electrostatic forces, coordination bonds, and etc. A practical and simple immobilization strategy by metal ions coordination for multimeric dehydrogenase was developed. 相似文献
7.
Short-chain acyl-CoA dehydrogenase (SCAD) is one of four straight-chain length specific enzymes involved in the first step
of fatty acid β-oxidation. To further understand the similarities between the members of this gene family, to characterize
how the gene is regulated, and to determine if there is coordinate regulation between these similar genes, we have isolated
genomic clones containing the mouse Acads gene. We show that Acads is a compact, single-copy gene approximately 5000 bp in size. We sequenced the entire coding portion of the gene, all of
the intron/exon junctions, and an 850-bp segment upstream of the translation start site. We have determined that the gene
consists of 10 exons ranging in size from 57 bp to 703 bp, and 9 introns ranging in size from 80 bp to approximately 700 bp.
The 5′ region of the mouse Acads gene lacks a TATA box or a CAAT box, is GC rich, and also lacks any similarity to the related gene, medium-chain acyl-CoA
dehydrogenase. This is the initial report of the gene structure and 5′ regulatory sequence of the short-chain acyl-CoA dehydrogenase
gene in any species.
Received: 20 September 1995 / Accepted: 4 December 1995 相似文献
8.
S. M. Ghaderian A. Mohtadi R. Rahiminejad R. D. Reeves A. J. M. Baker 《Plant and Soil》2007,293(1-2):91-97
Serpentine soils, which contain relatively high concentrations of nickel and some other metals, are the preferred substrate
for some plants, especially those that accumulate Ni in their tissues. In temperate regions more Ni-hyperaccumulator plants
are found in Alyssum than in any other genus. In this study, serpentine soils of two areas (Marivan and Dizaj) in the west/northwest of Iran and
also perennial Alyssum plants growing on these soils were analyzed for Ni and some other metals. The highest concentrations of total metals in the
soils of these areas for Ni, Cr, Co and Mn were 1,350, 265, 94 and 1,150 μg g−1, respectively, while concentrations of Fe, Mg and Ca reached 3.55%, 16.8% and 0.585% respectively. The concentration of exchangeable
Ni in these soils is up to 4.5 μg g−1. In this study two Alyssum species, A. inflatum and A. longistylum, have been collected from Marivan and Dizaj, respectively. Analysis of leaf dry matter shows that they can contain up to
3,700 and 8,100 μg Ni g−1, respectively. This is the first time that such high Ni concentrations have been found in these species. The concentrations
of other metals determined in these species were in the normal range for serpentine plants, except for Ca, which was higher,
up to 5.3% and 3.5%, respectively 相似文献
9.
Békésiová B Hraska S Libantová J Moravcíková J Matusíková I 《Molecular biology reports》2008,35(4):579-588
Plant chitinases belong to so-called pathogenesis related proteins and have mostly been detected in plants exposed to phytopathogenic
viruses, bacteria or fungi. A few studies revealed that they might also be involved in plant defence against heavy metals.
This work was undertaken to monitor the accumulation of chitinases in a set of heavy-metal stressed plants and bring evidence
on their involvement during this kind of stress. Roots of different plant species including Vicia faba cvs. Aštar and Piešťansky, Pisum sativum, Hordeum vulgare, Zea mays and Glycine max were exposed to different concentrations of lead (300 and 500 mg l−1 Pb2+), cadmium (100 and 300 mg l−1 Cd2+) and arsenic (50 and 100 mg l−1 As3+). In each case, the toxicity effects were reflected in root growth retardation to 80–10% of control values. The most tolerant
were beans, most sensitive was barley. Extracts from the most stressed roots were further assayed for chitinase activity upon
separation on polyacrylamide gels. Our data showed that in each combination of genotype and metal ion there were 2–5 different
chitinase isoforms significantly responsive to toxic environment when compared with water-treated controls. This confirms
that chitinases are components of plant defence against higher concentrations of heavy metals. In addition, accumulation of
some isoforms in response to one but not to other metal ions suggests that these enzymes might also be involved in a more
(metal) specific mechanism in affected plants and their biological role is more complex than expected. 相似文献
10.
The hypothesis that hyperaccumulation of certain metals in plants may play a role in osmotic adjustment under water stress (drought) was tested in the context of nickel hyperaccumulator Stackhousia tryonii. Field-collected mature plants of S. tryonii, grown in native ultramafic soil, were pruned to soil level and the re-growth exposed to five levels of water stress (20, 40, 60, 80 and 100% field capacity; FC) for 20 weeks. Water stress had significant (P<0.05) influence on growth (biomass), water potential and shoot Ni concentrations, with progressively more impact as water stress was increased from 80 to 40% FC. Shoot Ni concentration increased significantly from 3,400 μg g−1 dry weight (at 100% FC) to 9,400 μg g−1 dry weight (at 20% FC). Assuming that Ni is uniformly distributed through the shoot tissue, the Ni concentration could account for 100% at the 80 and 60% FC conditions, and 50% at the 40 and 20% FC conditions of plant osmotic regulation. The results are consistent with a role of Ni in osmotic adjustment and protection of S. tryonii plants against drought. 相似文献
11.
U. Oluoha 《Biologia Plantarum》1988,30(3):210-218
Physiological regions of yam tubers were morphologically defined in different specie into ‘Head’, ‘Middle’ and ‘Tail’, while
the limits of these regions were studied using phosphorylase activity. Variation in enzyme activity, pH and protein concentration
was found in different regions of the tubers. Old yam tubers had significantly higher activities of saccharide degrading enzymes,
hexokinase, phosphorylase, glucose-6-phosphate dehydrogenase, phosphofructokinase and pyruvate kinase, than the new tubers.
However, activity of phosphofructokinase in newD. rotundata was higher than that of old tuber. The high activity of phosphorylase in different regions of all the yam tubers examined
indicates a very important role of this enzyme in starch degradation inDioscorea species. The measured pH and protein concentration were also higher in old yam tubers. Except for phosphorylase, these enzymes
had alkaline pH optima. 相似文献
12.
The study of free amino acid content in Yarrowia lipolytica cells grown on ethanol under thiamine deficiency showed that glutamate, alanine, and γ-aminobutyric acid (γ-ABA) occurred
in the highest concentrations among the present 17 free amino acids. The culture liquid contained no amino acids. Analysis
of the enzymes of oxidative metabolism in the yeast grown under these conditions showed that the cell-free homogenate contained
substantial activity of glutamate decarboxylase, γ-ABA transaminase, and succinyl semialdehyde dehydrogenase. This result
indicated the formation of succinate from glutamate in a reaction catalyzed by 4-aminobutyrate aminotransferase (γ-aminobutyrate
bypass) under severe thiamine deficiency. These studies lead to the conclusion that cultivation of the yeast Y. lipolytica on ethanol under thiamine deficiency causes adaptive stress-induced metabolic changes. Increase of ammonium nitrogen consumption
and excretion of α-ketoglutaric acid are indicative of physiological changes, the functioning of the γ-aminobutyrate bypass
and high activity of malate dehydrogenase are manifestations of metabolic changes, and increased activities of the transamination
reactions reflect the changes in nitrogen metabolism. 相似文献
13.
Kavitha P Ramesh R Bupesh G Stalin A Subramanian P 《In vitro cellular & developmental biology. Animal》2011,47(10):698-706
The potential protective role of Tribulus terrestris in acetaminophen-induced hepatotoxicity in Oreochromis mossambicus was investigated. The effect of oral exposure of acetaminophen (500 mg/kg) in O. mossambicus at 24-h duration was evaluated. The plant extract (250 mg/kg) showed a remarkable hepatoprotective activity against acetaminophen-induced
hepatotoxicity. It was judged from the tissue-damaging level and antioxidant levels in liver, gill, muscle and kidney tissues.
Further acetaminophen impact induced a significant rise in the tissue-damaging level, and the antioxidant level was discernible
from the enzyme activity modulations such as glutamate oxaloacetic transaminase, glutamate pyruvic transaminase, alkaline
phosphatase, acid phosphatase, glucose-6-phosphate dehydrogenase, lactate dehydrogenase, superoxide dismutase, catalase, glutathione
peroxidase, glutathione reductase, glutathione S-transferase, lipid peroxidase and reduced glutathione. The levels of all
these enzymes have significantly (p < 0.05) increased in acetaminophen-treated fish tissues. The elevated levels of these enzymes were significantly controlled
by the treatment of T. terrestris extract (250 kg/mg). Histopathological changes of liver, gill and muscle samples were compared with respective controls.
The results of the present study specify the hepatoprotective and antioxidant properties of T. terrestris against acetaminophen-induced toxicity in freshwater fish, O. mossambicus. 相似文献
14.
Pathways of autotrophic CO2 fixation and of dissimilatory nitrate reduction to N2O in Ferroglobus placidus 总被引:1,自引:0,他引:1
J. A. Vorholt Doris Hafenbradl Karl O. Stetter Rudolf K. Thauer 《Archives of microbiology》1997,167(1):19-23
The strictly anaerobic Archaeon Ferroglobus placidus was grown chemolithoautotrophically on H2 and nitrate and analyzed for enzymes and coenzymes possibly involved in autotrophic CO2 fixation. The following enzymes were found [values in parentheses = μmol min–1 (mg protein)–1]: formylmethanofuran dehydrogenase (0.2), formylmethanofuran:tetrahydromethanopterin formyltransferase (0.6), methenyltetrahydromethanopterin
cyclohydrolase (10), F420-dependent methylenetetrahydromethanopterin dehydrogenase (1.5), F420-dependent methylenetetrahydromethanopterin reductase (0.4), and carbon monoxide dehydrogenase (0.1). The cells contained
coenzyme F420 (0.4 nmol/mg protein), tetrahydromethanopterin (0.9 nmol/ mg protein), and cytochrome b (4 nmol/mg membrane protein). From the enzyme and coenzyme composition of the cells, we deduced that autotrophic CO2 fixation in F. placidus proceeds via the carbon monoxide dehydrogenase pathway as in autotrophically growing Archaeoglobus and Methanoarchaea species. Evidence is also presented that cell extracts of F. placidus catalyze the reduction of two molecules of nitrite to 1 N2O with NO as intermediate (0.1 μmol N2O formed per min and mg protein), showing that – at least in principle –F. placidus has a denitrifying capacity.
Received: 23 August 1996 / Accepted: 6 November 1996 相似文献
15.
Galdieria sulphuraria (Galdieri) Merola can grow heterotrophically on at least ten different polyols. We investigated their metabolic path to glycolysis/gluconeogenesis
and identified two NAD-dependent polyol dehydrogenases. Activity of other enzymes metabolizing mannitol or sorbitol could
not be detected. The two dehydrogenases had a broad substrate specificity and were termed xylitol dehydrogenase (EC 1.1.1.14;
substrate specificity: xylitol > d-sorbitol > d-mannitol > l-arabitol) and d-arabitol dehydrogenase (EC 1.1.1.11; substrate specificity: d-arabitol > l-fucitol > d-mannitol > d-threitol) according to the substrate with the lowest K
m value. The xylitol dehydrogenase was stable during purification. In contrast, the d-arabitol dehydrogenase was thermolabile and depended on divalent ions for stability and activity, preferentially Mn2+ and Ni2+. The molecular mass of the xylitol dehydrogenase was estimated to be 295 kDa by size-exclusion chromatography and 220 kDa
by rate-sedimentation centrifugation. The d-arabitol dehydrogenase had a molecular mass of 105 kDa as determined by rate-sedimentation centrifugation. The specific activity
of both enzymes increased about fourfold when cells were transferred from autotrophic to heterotrophic conditions regardless
of whether sugars or polyols were supplied as substrates. The significance of polyol metabolism in Galdieria sulphuraria with regard to the natural habitat of the alga is discussed.
Received: 15 January 1997 / Accepted: 12 February 1997 相似文献
16.
Kaur R. and Sood M. L. 1982. Haemonchus contortus: the in vitro effects of dl-tetramisole and rafoxanide on glycolytic enzymes. International Journal for Parasitology 12: 585–588. Various enzymes of glycolysis (hexokinase, phosphoglucomutase, phosphoglucoisomerase, adolase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, phosphoglyceromutase-enolase-pyruvate kinase and lactate dehydrogenase) have been detected in adult Haemonchus contortus. Low pyruvate kinase and lactate dehydrogenase activities suggested an alternate pathway from phosphoenolpyruvate. In vitro incubation had no significant effects on these enzymes and the worm was able to maintain normal metabolism for 12 h. Varying degrees of inhibition of glycolytic enzymes were observed with 50 μg/ml of dl-tetramisole and rafoxanide. The enzymes were inhibited to a greater extent by dl-tetramisole. These effects may block the glycolytic pathway and deprive the parasite of its ATP production. 相似文献
17.
T. P. Pirog T. A. Shevchuk Yu. A. Klimenko 《Applied Biochemistry and Microbiology》2010,46(6):599-606
Activity of key enzymes of n-alkane metabolism was determined in cells of Rhodococcus erythropolis EK-1, a surfactant producer grown on n-hexadecane. Potassium cations were found to inhibit alkane hydroxylase and NADP+-dependent aldehyde dehydrogenase, while sodium cations were found to activate these enzymes. Decreased potassium concentration
(to 1 mM), increased sodium concentration (to 35 mM), and addition of 36 μmol/l Fe(II), required for alkane hydroxylase activity,
resulted in increased activity of the enzymes of n-hexadecane metabolism and in a fourfold increase of surfactant synthesis. A 1.5–1.7-fold increase in surfactant concentration
after addition of 0.2% fumarate (gluconeogenesis precursor) and 0.1% citrate (lipid synthesis regulator) to the medium with
n-hexadecane results from enhanced synthesis of trehalose mycolates, as evidenced by a 3–5-fold increase in phosphoenolpyruvate
synthetase and trehalose phosphate synthase, respectively. 相似文献
18.
J. F. Martín 《Applied microbiology and biotechnology》1998,50(1):1-15
Penicillins, cephalosporins and cephamycins are peptide antibiotics synthesized by condensation of l-α-aminoadipic acid, l-cysteine and l-valine to form the tripeptide δ(l-α-aminoadipyl)-l-cysteinyl-d-valine (Aad-Cys-Val) by a non-ribosomal peptide synthetase. The genes pcbAB and pcbC, common to all penicillin and cephalosporin producers, that encode the Aad-Cys-Val synthetase1 and isopenicillin N (IPN) synthase1 respectively, have been cloned and the encoded enzymes studied in detail. The IPN synthase has been crystallized and its
active center identified, providing evidence for the molecular mechanism of cyclization of the tripeptide Aad-Cys-Val to isopenicillin
N. The late genes of the penicillin and cephalosporin pathways have also been characterized although some of the molecular
mechanisms catalyzed by the encoded enzymes (e.g. IPN acyltransferase) are still obscure. In cephamycin-producing organisms,
biosynthesis of the α-aminoadipic acid precursor proceeds in two steps catalyzed by lysine 6-aminotransferase and piperideine-6-carboxylic
acid dehydrogenase. The gene lat for the first of these enzymes is located in the cephamycin gene cluster, providing an interesting example of association
of genes encoding enzymes for the formation of a precursor with genes involved in assembly of the antibiotics. Novel enzymes
involved in methoxylation at C-7 and carbamoylation at C-3′ of the cephem nucleus were isolated from Nocardia lactamdurans and Streptomyces clavuligerus. The methoxylation system is encoded by two linked genes cmcI-cmcJ and their products (proteins P7 and P8) form a complex that is required for hydroxylation at C-7 and for the subsequent methylation of the 7-hydroxycephem derivative
to form the methoxyl group. Carbamoylation at the C-3′-hydroxyl group of the cephem nucleus is catalyzed by a specific carbamoyltransferase
encoded by the gene cmcH. Finally, genes for a β-lactamase (bla), a penicillin-binding protein (pbp) and a transmembrane protein (cmcT) that appears to be involved in cephamycin exportation, are clustered together with the biosynthetic genes in the cephamycin
clusters of S. clavuligerus and N. lactamdurans. Availability of the cloned genes allows metabolic engineering of the β-lactam biosynthetic pathways such as a channelling
precursors and directed removal of bottlenecks in the β-lactam biosynthetic pathways. Several new β-lactam antibiotics have
been discovered in gram-positive and gram-negative bacteria that will provide new genes for combinatorial synthesis of new
molecules.
Received: 2 December 1997 / Received revision: 20 February 1998 / Accepted: 24 February 1998 相似文献
19.
Yoval-Sánchez B Jasso-Chávez R Lira-Silva E Moreno-Sánchez R Rodríguez-Zavala JS 《Journal of bioenergetics and biomembranes》2011,43(5):519-530
Ethanol is one of the most efficient carbon sources for Euglena gracilis. Thus, an in-depth investigation of the distribution of ethanol metabolizing enzymes in this organism was conducted. Cellular
fractionation indicated localization of the ethanol metabolizing enzymes in both cytosol and mitochondria. Isolated mitochondria
were able to generate a transmembrane electrical gradient (Δψ) after the addition of ethanol. However, upon the addition of
acetaldehyde no Δψ was formed. Furthermore, acetaldehyde collapsed Δψ generated by ethanol or malate but not by D-lactate.
Pyrazole, a specific inhibitor of alcohol dehydrogenase (ADH), abolished the effect of acetaldehyde on Δψ, suggesting that
the mitochondrial ADH, by actively consuming NADH to reduce acetaldehyde to ethanol, was able to collapse Δψ. When mitochondria
were fractionated, 27% and 60% of ADH and aldehyde dehydrogenase (ALDH) activities were found in the inner membrane fraction.
ADH activity showed two kinetic components, suggesting the presence of two isozymes in the membrane fraction, while ALDH kinetics
was monotonic. The ADH Km values were 0.64–6.5 mM for ethanol, and 0.16–0.88 mM for NAD+, while the ALDH Km values were 1.7–5.3 μM for acetaldehyde and 33–47 μM for NAD+. These novel enzymes were also able to use aliphatic substrates of different chain length and could be involved in the metabolism
of fatty alcohol and aldehydes released from wax esters stored by this microorganism. 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