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1.
Formation of a Tree having a Low Lignin Content 总被引:2,自引:0,他引:2
Received 30 September 2001/ Accepted in revised form 26 October 2001 相似文献
2.
Summary The horseradish-peroxidase (HRP) technique was used to visualize the cell bodies of axons projecting to the goldfish pituitary. Following intravenous injections of HRP, HRP reaction products were observed in axons of the rostral pars distalis, proximal pars distalis, neurointermediate lobe, pituitary stalk and in axons coursing from the pituitary into the hypothalamus. HRP-labelled cells in the brain were localized in two regions only — the nucleus preopticus (NPO) pars magnocellularis and pars parvocellularis, and the nucleus lateralis tuberis (NLT) of the hypothalamus. These observations suggest that the NPO and NLT are the source of the neurosecretory innervation of the goldfish pituitary. 相似文献
3.
The photosynthetic membranes of Anacystis nidulans R2 were examined electrophoretically following solubilization with lithium dodecyl sulfate. Electrophoresis yielded six prominent chlorophyll-containing bands. In addition, five polypeptides were observed which possessed heme-dependent peroxidase activity, monitored by incubating gels with 3,3′,5,5′-tetramethylbenzidine plus hydrogen peroxide. One such polypeptide, at 105 kdaltons, was removed by repeated washing of the membranes. Four remaining peroxidase-active polypeptides were observed at 7.2, 13.5, 18.5 and 33 kdaltons. Further examination of these four polypeptides yielded the following results. (1) The mobility of the 33 kdalton polypeptide was altered from 29 to 33 kdaltons upon heating (70°C) during membrane solubilization. (2) All four polypeptides showed stable heme-protein associations in the presence of 8 M urea; however, in the presence of urea, alterations in protein mobility were observed for each poly-peptide and only two (at 13.5 and 33 kdaltons) showed peroxidase activity following heating (70°C) during membrane solubilization. (3) The presence of thiols during membrane solubilization at 0°C was required to observe peroxidase activity at 7.2 kdaltons. These results, when compared to known properties of isolated cytochromes, suggest that the four polypeptides characterized here correspond to the subunits of photosynthetic cytochromes. Electrophoretic assessment of maize mutants lacking cytochrome f and b6 activity supports this suggestion. 相似文献
4.
Aquaspirillum magnetotacticum MS-1 cells cultured microaerobically (dissolved O2 tension 1% of saturation), expressed proteins with superoxide dismutase (SOD) activity. The majority (roughly 95%) of total cell superoxide dismutase activity was located in the cell periplasm with little or no activity in the cell cytoplasm. Irontype SOD (FeSOD) contributed 88% of the total activity activity detected, although a manganese-type SOD (MnSOD) was present in the periplasm as well. Cells cultured at a higher dissolved O2 tension (10% of saturation) expressed increased activity of the MnSOD relative to that of the FeSOD. 相似文献
5.
An analysis of substrate binding interactions in the heme peroxidase enzymes: A structural perspective 总被引:1,自引:0,他引:1
Andrea Gumiero Clive L. Metcalfe Emma Lloyd Raven 《Archives of biochemistry and biophysics》2010,500(1):13-14484
The interactions of heme peroxidase enzymes with their substrates have been studied for many years, but only in the last decade or so has structural information begun to appear. This review looks at crystal structures for a number of heme peroxidases in complex with a number of (mainly organic) substrates. It examines the nature and location of the binding interaction, and explores functional similarities and differences across the family. 相似文献
6.
Genetic analysis of a proposed cis-acting temporal locus ( Adh-3t ), which regulates alcohol dehydrogenase C2 (ADH-C2 ) acitivity in mouse epididymis extracts, among F1 (ddN × BALB/c) × ddN male backcross progeny provided evidence for genetic distinctness between the structural ( Adh-3 ) and temporal ( Adh-3t ) loci on chromosome 3. Genetic analysis also confirmed the close, linkage of Adh-1 (encoding liver and kidney ADH-A2 ) and Adh-3 (encoding stomach ADH-C2 ) to within 0.3 centimorgans on the mouse genome. Evidence is presented for a proposed closely linked cis-acting temporal locus (designated Adh-1t ) for the A2 isozyme (encoded by Adh-1 ) controlling the activity of this enzyme in mouse kidney extracts, but having no apparent affect on liver and intestine ADH-A2 activities. An extensive survey of the distribution of Adh-1, Adh-3 and Adh-3t alleles among 65 strains of mice is reported — with the exception of two Japanese strains (ddN and KF), linkage disequilibrium between Adh-3 and Adh-3t was observed. Sex differences in mouse liver and kidney ADH-A2 activities were observed, with male/female ratios of approximately 0.6 and 3 respectively for these tissue extracts. 相似文献
7.
J.Keith McClung Rolf F. Keltzien 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,678(1):106-114
Native polyacrylamide gels have been used to resolve protein kinase isoenzymes from cultured cells and the protein kinases have been identified by carrying out phosphorylation reactions in the gel. Following electrophoresis, the gels were incubated with histome and [γ-32P]ATP. The gels were then thoroughly washed and dried down, and the protein kinases were located by autoradiography. Protein kinase activity as measured in the gel system was a linear function of cytosol protein concentration up to about 100 μg per channel and incorporation of 32P into histone was time dependent. Three bands of protein kinase activity were resolved in cytosol samples from baby hamster kidney (BHK) fibroblasts. The band with the lowest relative mobility utilized histone IIA or casein equally well as substrate protein whereas bands 2 and 3 demonstrated a clear preference for histone. Bands 2 and 3 displayed a relative mobility in electrophoresis that was identical to that observed for cyclic AMP-dependent protein kinases I and II from rat liver. Treatment of cyctosol samples with cyclic AMP prior to electrophoresis resulted in the disappearance of cyclic AMP-dependent protein kinases from the gel profile. This method was employed to identify bands 2 and 3 as cyclic AMP-dependent protein kinases. The protein kinases in growth-arrested cells were compared with proliferating cells. We have observed a 3.5-fold increase in the activity of Type II protein kinase as the cells arrest growth in G1 phase of the cell cycle. This increase in Type II is correlated with the increase in cells blocked in G1 and a decrease in II Type activity appears to be an early event in permitting cells to leave G1 and resume growth. 相似文献
8.
Michaela Patila Ioannis V. Pavlidis Evmorfia K. Diamanti Petros Katapodis Dimitrios Gournis Haralampos Stamatis 《Process Biochemistry》2013,48(7):1010-1017
The effect of carbon-based nanomaterials (CBNs), such as multi-wall carbon nanotubes (CNTs) and graphene oxide (GO) nanomaterials functionalized with carboxyl, alkyl and amine groups, on the peroxidase-like activity and structure of cytochrome c (cyt c) was investigated. The catalytic efficiency of cyt c increases up to 78-fold in the presence of graphene oxide and up to 2.5-fold in the presence of other functionalized CBNs. Moreover, the use of functionalized CBNs enhances the thermal stability of the protein as well as its tolerance against hydrogen peroxide up to 2.5-fold. UV–vis and circular dichroism spectroscopy studies suggest that the increase in the peroxidase activity of cyt c in the presence of some functionalized GO nanomaterials, correlates to perturbations of the heme microenvironment, while the secondary structure of the enzyme remains intact. These results indicate that the beneficial effect the functionalized CBNs have on the activity and on the stability of cyt c depends on CBNs geometry and surface functionalization. 相似文献
9.
10.
Isolation of soil Streptomyces strains capable of degrading humic acids and analysis of their peroxidase activity 总被引:8,自引:0,他引:8
Abstract Fifteen Streptomyces strains capable of decolorizing humic acids in presence of glucose were isolated from soil samples using the dilute suspension technique and spread on agar plates. Six strains, displaying a significant and stable activity, were selected for further characterization. Some features of these isolates (carbon source utilization, enzyme production, antibiotic resistance) were compared with those of the reference strain Streptomyces viridosporus ATCC 39115. Degradation properties studied in batch cultures at pH 7.0 showed that the catabolic activity on humic acids was generally stimulated by incubation with 100% oxygen and was cell surface-associated. Peroxidase activity from cell-free extracts was analysed by using the oxidation of N,N,N′,N′-tetramethyl-phenylene-diamine. PAGE analysis revealed the existence of two major types of peroxidases (molecular mass: about 39.2 and 61.6 kDa), dividing the strains into two groups. The role of cell surface-associated peroxidase activity in the breakdown of humic acids is discussed. 相似文献