共查询到20条相似文献,搜索用时 31 毫秒
1.
The reductant of ferricytochrome c2 in Rhodopseudomonas sphaeroides is a component, Z, which has an equilibrium oxidation-reduction reaction involving two electrons and two protons with a midpoint potential of 155 mV at pH 7. Under energy coupled conditions, the reduction of ferricytochrome c2 by ZH2 is obligatorily coupled to an apparently electrogenic reaction which is monitored by a red shift of the endogeneous carotenoids. Both ferricytochrome c2 reduction and the associated carotenoid bandshift are similarly affected by the concentrations of ZH2 and ferricytochrome c2, pH, temperature the inhibitors diphenylamine and antimycin, and the presence of ubiquinone. The second-order rate constant for ferricytochrome c2 reduction at pH 7.0 and at 24°C was 2 · 109 M?1 · s?1, but this varied with pH, being 5.1 · 108 M?1 · s?1 at pH 5.2 and 4.3 · 109 M?1 · s?1 at pH 9.3. At pH 7 the reaction had an activation energy of 10.3 kcal/mol. 相似文献
2.
Toru Shimizu Masahiro Hatano Seiji Nagao Yoshinori Nozawa 《Biochemical and biophysical research communications》1982,106(4):1112-1118
43Ca NMR spectra of Ca2+-Tetrahymena calmodulin(Tet. CaM.) complexes have been observed under various conditions. Off-rate of Ca2+ from Tet. CaM. is estimated to be approx. 2.7 × 103 s?1 under a certain assumption. Relaxation rates of 43Ca NMR of Ca2+-Tet. CaM. are remarkably increased(by one order in magnitude) by adding trifluoperazine(TFP), a potent calmodulin antagonist. Relaxation parameters estimated suggest that Ca2+ mobility is reduced by the TFP binding. A stoichiometry of TFP is two moles per Tet. CaM. molecule. The relaxation rates of 43Ca NMR signals are increased by adding excessive Mg2+ to the Ca2+-Tet. CaM. solutions. The addition of Mg2+ to the Ca2+-Tet. CaM. complex decreases apparent pKa value of the complex as well. 相似文献
3.
Complexes of the types cis- and trans-Pt(amine)2I2 were studied by spectroscopic methods, especially by multinuclear NMR spectroscopy. In 195Pt NMR, the cis diiodo compounds with primary amines were observed between −3342 and −3357 ppm in acetone, while the trans compounds were found between −3336 and −3372 ppm. For the secondary amines, the chemical shifts were observed at lower fields. In 1H NMR, the trans complexes were observed at higher fields than the cis compounds, while in 13C NMR, the reverse was observed. The 2J(195Pt-1H) and 3J(195Pt-1H) coupling constants are larger for the cis compounds (ave. 67 and 45 Hz, respectively) than for the trans isomers (ave. 59 and 38 Hz). In 13C NMR, the values of 2J(195Pt-13C) and 3J(195Pt-13C) were also found to be larger for the cis complexes (ave. 17 and 39 Hz versus 11 and 28 Hz). There seems to be a slight dependence of the pKa values of the protonated amines or the proton affinity in the gas phase with the δ(Pt) chemical shifts. The crystal structures of eight diiodo complexes were determined. These compounds are cis-Pt(CH3NH2)2I2, cis-Pt(n-C4H9NH2)2I2, cis-Pt(Et2NH)2I2, trans-Pt(n-C3H7NH2)2I2, trans-Pt(iso-C3H7NH2)2I2, trans-Pt(n-C4H9NH2)2I2, trans-Pt(t-C4H9NH2)2I2 and trans-Pt(Me2NH)2I2. The Pt-N bond distances located in trans position to the iodo ligands were compared to those located in trans position to the amines. The Pt-N bond in cis-Pt(Et2NH)2I2 are much longer than the others, probably caused by the steric hindrance of the two very bulky ligands located in cis positions. 相似文献
4.
Complexes of the types cis- and trans-Pt(amine)2I2 containing cyclic amines were synthesized and studied mainly by IR and multinuclear NMR spectroscopies. The compounds were converted to cis- and trans-Pt(amine)2(NO3)2, which were also investigated. The hydrolysis and the aquation reactions of the latter compounds were then studied in D2O in different conditions of pH. In acidic medium, the aqueous product is [Pt(amine)2(D2O)2]2+ and for a few amines, [Pt(amine)2(D2O)(NO3)]+ was detected. In basic pH, the main product is Pt(amine)2(OD)2 and Pt(amine)2(OD)(NO3) was detected for several compounds. In neutral pH, the cis isomers form between two and four species in fresh solutions. The most shielded species in 195Pt NMR is the monoaqua-monohydroxo complex cis-[Pt(amine)2(D2O)(OD)]+ and the less shielded compound is the dihydroxo-bridged dimer [Pt(amine)2(μ-OD)2Pt(amine)2]2+, which were observed for all the compounds. For a few amines, the monohydroxo-bridged dimer [Pt(D2O)(amine)2(μ-OD)Pt(OD)(amine)2]2+ was detected and for cyclohexylamine, a fourth signal was assigned to a cyclic hydroxo-bridged trimer [(Pt(amine)2(μ-OD))3]3+. 195Pt NMR spectroscopy has shown that the concentration of the monomer decreases with time, while the concentration of the dimers increases. Only one product was observed for the trans isomers in neutral pH. The signal was assigned to the monoaqua-monohydroxo species trans-[Pt(amine)2(D2O)(OD)]+. The 13C and 1H NMR spectra of most of the complexes were measured. All the coupling constants 2,3J(195Pt-1H) and 2,3J(195Pt-13C) are larger in the cis compounds than in the trans isomers. 相似文献
5.
Hubert L. Dulieu 《Mutation research》1974,25(3):289-304
A greenish-yellow mutant was obtained after treatment of seeds of Nicotiana tabacum L. var. Xanthi n.c. with ethyl methanesulfonate (EMS). Two genetically independent mutations (a1 and a2) were isolated. The first mutation (a1) antagonizes the function of its partially dominant a1+ allele. The second mutation (a2) is amorphous but strongly interacts with a1.Among the nine possible genotypes at the two loci, five varied in somatic cells. The heterozygous state a1+/a1 strongly increased the frequency of both spontaneous and induced variations. However, two homozygotes also showed variations.Variants were isolated from induced and spontaneous non-reciprocal and reciprocal variations within paliside tissues by bud induction in vitro. They were genetically tested. In this first paper, only non-reciprocal variations are reported.Green variants from the greenish-yellow (J1) dihybrid a1+/a1a2+/a2 clone had two genotypes: the first was due to true reversions of a1 to a1+, whereas the second was due to amorphous a10 mutations from a1. These a10 mutations may well be deletions.The lightest yellow variants from J1 were due to mutations either from a1+ into a1 or from a2+ into a2.Deletions at the a1+?a1 locus led to either yellow variations when a1+ was lost, or to false reversions when the antagonistic allele a1 was lost.Amorphous alleles at the a1+?a1 locus were also isolated from tissues other than J+. They gave zygotic lethality (s) that probably varied with the size of the deletions. Thus, true reversions and deletions at the a1+?a1 locus could be distinguished from one another by progeny tests.Other variants showed higher frequencies of spontaneous variations (instability). Somatic changes observed in these unstable systems were due to modifications at the marker loci. The genetic nature of this instability is not yet known.There is strong evidence that the genetic events involved in these non-reciprocal variations were deletions, conversions and point mutations. True reversions from a1 into a1+ and new mutations from a1+ into a1 were obtained only from a1+/a1. It was therefore supposed that the changes observed took place only in heterozygotes, and the conversion hypothesis was made. Attempts are being made to prove that conversions do exist in higher plants, and to find out if this process, as deletions, is induced by radiation. 相似文献
6.
Two equivalents of 2-diphenylphosphinobenzoic acid react with 1,2-ethanedithiol and 1,8-diaminonaphthalene under peptidic coupling conditions to give the new ligands 1,2-bis-S-[2′-(diphenylphosphino)benzoyl]dithioethane (dppte) (1) and 1,2-bis-N-[2′-(diphenylphosphino)benzoyl]diaminonaphthalene (dppan) (2), respectively. 1 and 2 have been characterised by mass spectrometry, elemental analysis, NMR, IR spectroscopy, and by single-crystal X-ray structure analysis. 2 is easily oxidised by air to give the monophosphine oxide derivatives (3). Single-crystal X-ray structure analysis of 3 shows an intramolecular hydrogen bond between an amido and the phosphoryl oxygen atom. Compounds 1 and 2 react with [RuCl2(η6-p-cymene)]2 to give the dinuclear complexes [RuCl(η6-p-cymene)(dppte)RuCl(η6-p-cymene)]2+ (4) and [RuCl(η6-p-cymene)(dppan)RuCl(η6-p-cymene)]2+ (5). As determined by single-crystal X-ray structure analysis, 4 and 5 adopt different coordination modes to the ruthenium atoms. In 4 the symmetric dppte ligand is P,S coordinated to the ruthenium atom, whereas in 5 the dppan ligand prefers a P,O coordination mode. 相似文献
7.
1. Using stopped-flow technique we have investigated the electron transfer form cytochrome c to cytochrome aa3 and to the (porphyrin) cytochrome c-cytochromeaa3 complex.2. In a low ionic strength medium, the pre-steady state reaction occurs in a biphasic way with rate constants of at least 2 · 108 M?1 · s?1 and about 107 M?1 · s?1 (I = 8.8 mM, pH 7.0, 10° C), respectively.3. A comparison of the rate constants, determined in the presence of an excess of cytochrome c with those found in the presence of an excess of cytochrome aa3 reveals the existence of two slower reacting sites on the functional unit (2 hemes and 2 coppers) of cytochrome aa3. On basis of these results we discuss various models. If no site-site interactions are assumed (non-cooperative model) cytochrome aa3 has 2 high and 2 low affinity sites available for the reaction with ferrocytochrome c. If negative cooperativity occurs, cytochrome aa3 has 2 high affinity sites which change into 2 low affinity sites upon binding of one cytochrome c molecule. The latter model is favoured. 相似文献
8.
Geoffrey R. Bedford Peter J. Sadler 《Biochimica et Biophysica Acta (BBA)/General Subjects》1974,343(3):656-662
NMR titration curves have been recorded for all the 13C resonances of cis and trans in 2H2O. the measured pK2H values are 3.4 ± 0.8 and 4.13 ± 0.08 respectively; the free energy of ionization for the trans isomer being (3.8 kJ/mole) greater than for the cis. The ionization shifts of the two isomers differ significantly only at the acetyl carbonyl and Cγ positions. It is suggested that these are related to conformational changes which stabilize the trans form at low p2H. 相似文献
9.
Min Sang Fei Ma Jie Xie Xiao-Bo Chen Ke-Bin Wang Xiao-Chun Qin Wen-Da Wang Jing-Quan Zhao Liang-Bi Li Jian-Ping Zhang Ting-Yun Kuang 《Biophysical chemistry》2010
Electron paramagnetic resonance (EPR) spectroscopy was used to detect the light-induced formation of singlet oxygen (1O2*) in the intact and the Rieske-depleted cytochrome b6f complexes (Cyt b6f) from Bryopsis corticulans, as well as in the isolated Rieske Fe–S protein. It is shown that, under white-light illumination and aerobic conditions, chlorophyll a (Chl a) bound in the intact Cyt b6f can be bleached by light-induced 1O2*, and that the 1O2* production can be promoted by D2O or scavenged by extraneous antioxidants such as l-histidine, ascorbate, β-carotene and glutathione. Under similar experimental conditions, 1O2* was also detected in the Rieske-depleted Cyt b6f complex, but not in the isolated Rieske Fe–S protein. The results prove that Chl a cofactor, rather than Rieske Fe–S protein, is the specific site of 1O2* formation, a conclusion which draws further support from the generation of 1O2* with selective excitation of Chl a using monocolor red light. 相似文献
10.
Aryna V. Lado Alexander V. Piskunov Georgy K. Fukin Vladimir N. Ikorskii Vladimir K. Cherkasov 《Inorganica chimica acta》2005,358(15):4443-4450
Addition of 3,6-di-tert-butyl-o-benzoquinone (3,6-DBBQ) to SnCl2 in THF leads to the oxidation of Sn(II) to Sn(IV) with formation of catecholate complex (3,6-DBCat)SnCl2 · 2THF (1), where 3,6-DBCat is 3,6-di-tert-butyl-catecholate dianion. The reaction of 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzoquinone (IBQ-Pri) also proceeds on the oxidative-addition mechanism yielding bis-iminosemiquinonato species (ISQ-Pri)2SnCl2(2), where ISQ-Pri is anion-radical 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzosemiquinolate. The complexes have been characterized by IR, X-band EPR, 1H NMR (for 1) spectroscopy and magnetochemistry (for 2). X-ray analysis data show the distorted octahedral environment of tin(IV) for both complexes. Complex 1 is diamagnetic (ground state S = 0), while 2 has triplet ground state (S = 1, biradical). Catecholate complex 1 is able to be a spin trap for different organic radicals. 相似文献
11.
George A. Orr Donald T. Elmore 《Biochemical and biophysical research communications》1977,74(2):755-761
Several (N2-acetyl-N1-arylmethylcarbazoyl)-α-chymotrypsins with p-substituents in the N1-arylmethyl group have been prepared. Measurements of (a) accessibility of tryptophyl residues to modification by 2-hydroxy-5-nitrobenzyl bromide, (b) intrinsic fluorescence spectra in the absence and presence of sodium dodecyl sulphate, (c) thermal perturbation spectra indicate that, in general, tryptophyl residues are less accessible to solvent than in the free enzyme and the modified enzymes are more stable than α-chymotrypsin to denaturation by heat or sodium dodecyl sulphate. N2-Acetyl-N1-p-dimethylaminobenzylcarbazoyl-α-chymotrypsin, however, contains more accessible tryptophyl residues than the other derivatives and is thermally less stable although it is more stable than the free enzyme. 相似文献
12.
U. Casellato D. Fregona S. Tamburini P.A. Vigato R. Graziani 《Inorganica chimica acta》1985,110(1):41-46
Uranyl(VI) and thorium(IV) complexes of the type UO2(NO3)2(L1)2, UO2(NO3)2(L2)2, UO2(CH3COO)2L1, UO2(CH3COO)2L2, Th(NO3)4(L1)2 and Th(NO3)4(L2)2 (L1 = (2-nitro)phenyl-bis-phenyl phosphine oxide, L2 = triferrocenylphosphine oxide) are reported, together with their physico-chemical properties.The crystal structure of UO2(NO3)2(L1)2 is also reported. The crystals are monoclinic, space group P21/n with a = 17.78(1), b = 13.88(1), c = 17.37(1) Å, β = 114.8(1)° for Z = 4. The uranium atom is 8-coordinated, the uranyl(VI) group being equatorially surrounded by an irregular hexagon of six oxygen atoms from two trans neutral ligands and two nitrato groups. 相似文献
13.
Felix D. Sokolov Valery G. Shtyrlin Vasily V. Brusko Sergey V. Baranov Tadeusz Glowiak 《Inorganica chimica acta》2006,359(7):2087-2096
Thiourea, PhNHC(S)NHP(O)(OPri)2 (LH) chelates of CoII, NiII, and PdII ions have been obtained and investigated by single-crystal X-ray diffraction, UV, IR, NMR spectroscopy, and EI mass-spectrometry. The unusual 1,3-N,S-coordination via sulfur and NP(O) nitrogen atoms has been found in the trans-square-planar NiL2 and PdL2 complexes, whereas the 1,5-O,S-coordination is realized in the tetrahedral CoL2 complex. DFT calculations have revealed significant stabilization of the 1,3-N,S-structures due to stronger crystal field and the NH-OP hydrogen bonds. 相似文献
14.
Yusuke Kinoshita Motoki Kayama Yuichiro Kashiyama Hitoshi Tamiaki 《Bioorganic & medicinal chemistry letters》2018,28(6):1090-1092
Divinyl-132,173-cyclopheophorbide-a enol was in vivo produced as a metabolite of divinyl-chlorophyll-a by protists and in vitro prepared by the intramolecular cyclization of methyl divinyl-pyropheophorbide-a, one of the divinyl-chlorophyll-a derivatives. The 1H NMR spectra in CDCl3 showed that the obtained product took exclusively its enol form in the solution. The intramolecular cyclization of chlorin π-system at the C132 and C173 positions affected the optical properties of such chlorophyll derivatives including the non-fluorescent emission of the enol. 相似文献
15.
Current MR methods use T2? relaxation time as a surrogate measure of ligament strength. Currently, a multi-echo voxel-wise least squares fit is the gold standard to create T2? maps; however, the post-processing is time-intensive and serves as a stopgap for clinical use. The study objective was to determine if an alternative method could improve post-processing time without sacrificing fidelity of T2? values for eventual translational use in the clinic. Using a 6 echo FLASH sequence, three different methods were used to determine intact posterior cruciate ligament (PCL) median T2? Two of these methods utilized a voxel-wise method to establish T2? maps: (1) a current “gold standard” method using a voxel-wise 6 echo least-squares fit (6LS) and (2) a voxel-wise 2 echo point T2? determination (2MM). The third method used median ligament signal intensity and a single nonlinear least-squares fit (6LSROI) instead of a voxel-wise basis. The resulting median T2? values of the PCL and computational time were compared. The median T2? values were 42% higher using the 2MM compared to the 6LS method (p<0.0001). However, a strong correlation was found for the median T2? values between the 2MM and 6LS methods (R2=0.80). The median T2? values were not significantly different between the 6LS and 6LSROI methods (p=0.519). Using the 2MM (which provides a regional map) and the 6LSROI (which efficiently provides the median T2? value) methods in tandem would take only minutes of post-processing computational time compared to the 6LS method (~540 min), and hence would facilitate clinical application of T2? maps to predict ligament structural properties as a patient outcome measure. 相似文献
16.
Zahir Hussain Toru Uyama Katsuhisa Kawai Smriti Sultana Binte Mustafiz Kazuhito Tsuboi Nobukazu Araki Natsuo Ueda 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2018,1863(5):493-502
N-acyl-phosphatidylethanolamine (NAPE) is known to be a precursor for various bioactive N-acylethanolamines including the endocannabinoid anandamide. NAPE is produced in mammals through the transfer of an acyl chain from certain glycerophospholipids to phosphatidylethanolamine (PE) by Ca2+-dependent or -independent N-acyltransferases. The ε isoform of mouse cytosolic phospholipase A2 (cPLA2ε) was recently identified as a Ca2+-dependent N-acyltransferase (Ca-NAT). In the present study, we first showed that two isoforms of human cPLA2ε function as Ca-NAT. We next purified both mouse recombinant cPLA2ε and its two human orthologues to examine their catalytic properties. The enzyme absolutely required Ca2+ for its activity and the activity was enhanced by phosphatidylserine (PS). PS enhanced the activity 25-fold in the presence of 1?mM CaCl2 and lowered the EC50 value of Ca2+ >8-fold. Using a PS probe, we showed that cPLA2ε largely co-localizes with PS in plasma membrane and organelles involved in the endocytic pathway, further supporting the interaction of cPLA2ε with PS in living cells. Finally, we found that the Ca2+-ionophore ionomycin increased [14C]NAPE levels >10-fold in [14C]ethanolamine-labeled cPLA2ε-expressing cells while phospholipase A/acyltransferase-1, acting as a Ca2+-independent N-acyltransferase, was insensitive to ionomycin for full activity. In conclusion, PS potently stimulated the Ca2+-dependent activity and human cPLA2ε isoforms also functioned as Ca-NAT. 相似文献
17.
Gleb A. Abakumov Michail P. Bubnov Ludmila G. Abakumova Vladimir K. Cherkasov 《Inorganica chimica acta》2005,358(13):3829-3840
Four-coordinate complex MnIII(ISQ-Pri)(AP-Pri) (1), where ISQ-Pri = 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzosemiquinonate anion-radical, AP-Pri = 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-amidophenolate dianion, has been prepared by the reaction of Mn2(CO)10 with free 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzoquinone (IBQ-Pri) in the molar ratio 1:4 in toluene. In contrast to manganese, rhenium carbonyl reacts with o-iminobenzoquinone to form complex ReII(ISQ-Pri)2(CO)2 (2) with the retention of two carbonyls in coordination sphere of rhenium. The complexes have been characterized by IR, UV-Vis, and EPR spectroscopies. Molecular structures of compounds 1 and 2 have been determined by single-crystal X-ray crystallography. Compound 1 is centro-symmetric square-planar molecule with delocalized mixed valent state of AP-Pri and ISQ-Pri ligands. EPR spectrum of 1 in solid at 300-77 K is typical for manganese complexes with S = 3/2 state. The effective magnetic moment of 1 is 1.96 μB at temperature 5 K as it was established by variable-temperature magnetic susceptibility measurements. Six-coordinate octahedral complex 2 possesses an S = 1/2 ground state, which is attained via strong intramolecular antiferromagnetic interaction between t2g orbital unpaired electron of the low spin ReII ion and the unpaired electron on π-orbital of the radical ligand. 相似文献
18.
Complexes of the type [Pt(amine)4]I2 were synthesized and characterized mainly by multinuclear (195Pt, 1H and 13C) magnetic resonance spectroscopy. The compounds were prepared with different primary amines, but not with bulky amines, due to steric hindrance. In 195Pt NMR, the signals were observed between −2715 and −2769 ppm in D2O. The coupling constant 3J(195Pt-1H) for the MeNH2 complex is 42 Hz. In 13C NMR, the average values of the coupling constants 2J(195Pt-13C) and 3J(195Pt-13C) are 18 and 30 Hz, respectively. The crystal structure of [Pt(EtNH2)4]I2 was determined by X-ray diffraction methods. The Pt atom is located on an inversion center. The structure is stabilized by H-bonding between the amines and the iodide ions. The compound with n-BuNH2 was found by crystallographic methods to be [Pt(n-BuNH2)4]2I3(n-BuNHCOO). The crystal contains two independent [Pt(CH3NH2)4]2+ cations, three iodide ions and a carbamate ion formed from the reaction of butylamine with CO2 from the air. When the compound [Pt(CH3NH2)4]I2 was dissolved in acetone, crystals identified as trans-[Pt(CH3NH2)2(H3CNC(CH3)2)2]I2 were isolated and characterized by crystallographic methods. Two trans bonded MeNH2 ligands had reacted with acetone to produce the two N-bonded Schiff base Pt(II) compound. 相似文献
19.
Suzanne L. Shea 《Inorganica chimica acta》2005,358(5):1709-1714
Reaction of [{RuCl2(η6-MeC6H4isoPr)}2] with syn-[B18H22] and non-nucleophilic base results in [8-(η6-MeC6H4isoPr)-8-RuB17H21], of 18-vertex anti 10-vertex-nido-10-vertex-nido configuration, as the predominant product. The syn → anti configurational change arises from a trans-cluster pseudo-vertex-substitution of a {BH} vertex by the {Ru2(η6-MeC6H4isoPr)} centre. 相似文献
20.
Ca2+ regulates cell differentiation and morphogenesis in a diversity of organisms and dysregulation of Ca2+ signal transduction pathways leads to many cellular pathologies. In Dictyostelium Ca2+ induces ecmB expression and stalk cell differentiation in vitro. Here we have analyzed the pattern of ecmB expression in intact and bisected slugs and the effect of agents that affect Ca2+ levels or antagonize calmodulin (CaM) on this expression pattern. We have shown that Ca2+ and CaM regulate ecmB expression and pstAB/pstB cell differentiation in vivo. Agents that increase intracellular Ca2+ levels increased ecmB expression and/or pstAB and pstB cell differentiation, while agents that decrease intracellular Ca2+ or antagonize CaM decreased it. In isolated slug tips agents that affect Ca2+ levels and antagonize CaM had differential effect on ecmB expression and cell differentiation in the anterior versus posterior zones. Agents that increase intracellular Ca2+ levels increased the number of ecmB expressing cells in the anterior region of slugs, while agents that decrease intracellular Ca2+ levels or antagonize CaM activity increased the number of ecmB expressing cells in the posterior. We have also demonstrated that agents that affect Ca2+ levels or antagonize CaM affect cells motility and regeneration of shape in isolated slug tips and backs and regeneration of tips in isolated slug backs. To our knowledge, this is the first study detailing the pattern of ecmB expression in regenerating slugs as well as the role of Ca2+ and CaM in the regeneration process and ecmB expression. 相似文献