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991.
K. Kitamura C. S. Davies N. C. Nielsen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1984,68(3):253-257
Summary A cultivar lacking the glycinin subunit A5A4B3 (Raiden) was crossed with one lacking the -subunit of -conglycinin (Keburi). Analysis of F2 and F3 progeny indicated that the missing bands of the A5A4B3 and the -subunit were each controlled by a recessive allele of two independently segregating genes. Gene symbols Gy
4/gy
4 and Cgy
1/cgy
1 were proposed for the genes which confer the presence or absence of the glycinin and conglycinin subunits, respectively.Cooperative research of USDA-ARS and the Indiana Agric. Exp. Stn., Purdue Univ., West Lafayette, IN 47907, USA. Indiana Agric. Exp. Stn. Journal Article 9675. Financial support from the American Soybean Association Research Foundation is gratefully acknowledged 相似文献
992.
Bergmann Pascale Seyer Patrick Burkard Gérard Weil Jacques-Henri 《Plant molecular biology》1984,3(1):29-36
Tobacco chloroplast tRNAs have been purified by two-dimensional polyacrylamide gel electrophoresis, identified by aminoacylation, labelled at their 3-end and hybridized to tobacco chloroplast DNA restriction fragments, in order to establish a tRNA gene map. These hybridization studies have revealed the localization of at least seven genes in each inverted repeat region, a minimum of 22 tRNA genes in the large single copy region and one tRNA gene in the small single copy region. Comparison of the tobacco chloroplast tRNA gene map to that of maize shows many similarities, but also some differences suggesting that DNA sequence rearrangements have occurred in the chloroplast genome during evolution. 相似文献
993.
Photoconversion of protochlorophyllide650 form was observed in etiolated leaves illuminated with long-wavelength—690 nm—light. This process showed Shibata shift and was found to have a strong temperature dependence between 20 and –40°C. The low rate of reaction, the strong temperature dependence and calculations on the spectral overlap integral of absorption and fluorescence bands in this spectral region indicate that the phototransformation of the 650 nm form of protochlorophyllide may be caused by a back energy migration from a long-wavelength pigment form absorbing around 690 nm; this pigment form is probably a long-wavelength form of protochlorophyll/ide. 相似文献
994.
Purified maize leaf phosphoenolpyruvate carboxylase (EC 4.1.1.31) was completely inactivated by several thiol-modifying reagents, including, CuCl2, CdCl2 and N-ethylmaleimide. The inactivation by CuCl2 could be reversed by dithiothreitol, suggesting the involvement of vicinal dithiols in the inactivation process.Complete inactivation of phosphoenolpyruvate carboxylase was correlated with the incorporation of two mol (3H)N-ethylmaleimide per 100-kilodalton subunit. The total protection of the enzyme against N-ethylmaleimide inactivation afforded by the substrate, phosphoenolpyruvate, was correlated with the protection of one mol (3H)N-ethylmaleimide reactive residue per mol subunit.The complete inactivation of phosphoenolpyruvate carboxylase by N-ethylmaleimide and the protection afforded by phosphoenolpyruvate against modification suggest the presence of an essential cysteine residue in the catalytic site of the C4 leaf enzyme.Abbreviations PEP,
phosphoenolpyruvate
- Mops,
4-morpholinepropanesulphonic acid
(Consejo Nacional de Investigaciones Científicas y Técnicas, Fundación M. Lillo y U.N. de Rosario). 相似文献
995.
H.James Harwood Marita Schneider Peter W. Stacpoole 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1984,805(3):245-251
The activity of microsomal 3-hydroxy-3-methylglutaryl coenzyme A reductase (EC 1.1.1.34), obtained from cultured human IM-9 lymphoid cells or freshly isolated human peripheral blood leukocytes, is modulated by a phosphorylation/dephosphorylation mechanism. Addition of MgATP + ADP to IM-9 cell microsomal reductase leads to a time-dependent loss of enzyme activity. Inactivated reductase is reactivated by rat liver reductase phosphatase. Kinase-dependent IM-9 cell microsomal reductase, prepared by heating IM-9 microsomes for 15 min at 50°C, is inactivated in the presence of MgATP and ADP only after addition of cytosolic reductase kinase from either IM-9 cells, freshly isolated leukocytes or rat liver. Inactivation is time-dependent and dependent on the cytosolic protein concentration. Inactivated reductase is reactivated by rat liver reductase phosphatase. For cultured IM-9 cells and freshly isolated leukocytes incubated with culture medium for 2 h, the ratios of active (unphosphorylated) to total (phosphorylated + unphosphorylated) reductase activity are 0.22 and 0.43, respectively. Thus, in addition to its regulation by changes in the amount of total enzyme protein, human leukocyte reductase activity is also modulated by a phosphorylation/dephosphorylation mechanism. 相似文献
996.
Properties of phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) obtained from isolated guard-cell protoplasts of Vicia faba L. were determined following rapidly desalting of the extract on a Sephadex G 25 column. The activity of PEP carboxylase was measured as a function of PEP and malate concentration, pH and K+ concentration within 2–3 min after homogenization of the guard-cell protoplasts. The activity of this enzyme was stimulated by PEP concentrations of 0.1 to 0.75 mM and by K+ ions (12 mM), but inhibited by PEP concentrations above 1 mM and by malate. Changes in the Km(PEP) and Vmax values with increasing malate concentrations (2.5 and 5 mM) indicate that the malate level, varying in relation to the physiological state of guard cells, plays an important role in regulating the properties of phosphoenolpyruvate carboxylase.Abbreviations CAM
Crassulacean acid metabolism
- GCP
guard-cell protoplast
- PEP
phosphoenolpyruvate
Dedicated to Professor Dr. Hubert Ziegler on the occasion of his 60th birthday 相似文献
997.
In etiolated corn (Zea mays L.) and etiolated pea (Pisum sativum L.) seedlings, a gravitropic stimulation induces the deposition of callose. In the corn coleoptiles this occurs within 5 min of gravity stimulation, and prior to the beginning of curvature. Both gravitropic curvature and callose deposition reach their maxima by 12 h. Within the first 2 h more callose is deposited on the upper (concave) side, but after 2–3 h, this deposition pattern is reversed. An inhibitor of protein glycosylation, 2-deoxy-d-glucose (DDG), inhibits callose production and considerably retards gravitropic bending in both species of plants. Mannose can relieve the inhibition of gravitropic bending by DDG. The pea mutant Ageotropum, which does not respond to gravity when etiolated, also fails to produce callose in response to a gravitic stimulus. These correlations indicate that callose deposition may be a biochemical component of gravitropism in plant shoots.Abbreviation DDG
2-deoxy-d-glucose 相似文献
998.
Meiheng Yang Howard Allen Hisao Fukushima Richard A. DiCioccio 《Glycoconjugate journal》1984,1(1):15-19
Fucosidosis is an autosomal recessive lysosomal storage disease resulting from the absence of -l-fucosidase activity. Two natural missense mutations (G197A) and (A860G) within the -l-fucosidase gene have been reported to be homozygous in four patients with fucosidosis. Expression of wild-type and mutated -l-fucosidase cDNAs in COS-1 cells revealed complete deficiency of -l-fucosidase for the G197A transition and a normal level of enzyme for A860G. We therefore conclude that the change of G197A is responsible for fucosidosis in the patients while A860G is a normal polymorphic variant of -l-fucosidase. 相似文献
999.
Experimental support for the use of fluid aqueous organic solvent systems and subzero temperatures in mechanistic studies of -galactosidase is presented. The enzyme was stable and retained catalytic activity and structural integrity in 50% aqueous dimethyl sulfoxide and 60% aqueous methanol at 0°C; at lower temperatures higher concentrations of cosolvent may be successfully used. The effects of dimethyl sulfoxide on the catalytic and structural properties of the enzyme were investigated in detail. For the -galactoside-catalyzed h ydrolysis ofo-nitrophenyl--D-galactoside the value ofk
cat decreased in a linear manner with increasing cosolvent concentration, whereasK
m increased exponentially. The decrease ink
cat paralleled the decrease in water concentration, consistent with rate-limiting hydrolysis of a galactosylenzyme intermediate. The increase inK
m is attributed to less favorable partitioning of the substrate to the active site in the cryosolvent compared to aqueous solution. ThepH*-rate profile for this reaction at 0°C in 50% dimethyl sulfoxide was similar to that in aqueous solution, withpK*1=5.8 andpK*2=8.0. Linear Arrhenius plots, with energies of activation of 13.9 and 16.0 kcal mol–1, respectively, were obtained for the -galactosidase-catalyzed hydrolysis ofo-nitrophenyl- andp-nitrophenyl--D-galactosides in 50% dimethyl sulfoxide at temperatures to –57°C. Examination of the intrinsic fluorescence and ultraviolet spectra of the enzyme as a function of increasing cosolvent concentration showed no evidence for structural perturbation up to and including 50% dimethyl sulfoxide at 0°C. We conclude that these cryosolvent systems are suitable for mechanistic investigations of -galactosidase, in particular for trapping intermediates at subzero temperatures. 相似文献
1000.
Interactions of U1 RNP with heterogeneous nuclear RNA in rat Novikoff hepatoma nuclei 总被引:1,自引:0,他引:1
Fred R. Harmon Chirala S. Subrahmanyam Harris Busch 《Molecular and cellular biochemistry》1984,65(1):45-55
Summary The nature of the association of U1 RNA with rapidly sedimenting RNP structures in rat hepatoma nuclei was investigated. The effects of salt and proteinase K treatment on the stability of this bound form of U1 RNA were studied using sucrose density gradient analyses. Quantitation of the amount of U1 RNA remaining associated with large structures after treatment was used to assess the relative contribution of protein-protein(and protein-RNA) versus RNA-RNA interactions. Forty-eight percent of the total nuclear U1 RNA released by sonication was found in a bound form when the sonicate was centrifuged through gradients containing 50 mM NaCl. Fifty percent of this bound U1 RNA remained associated with rapidly sedimenting RNPs when the NaCl concentration was raised to 500 mM. To assess the contribution of protein independent interactions, large RNPs were completely deproteinized and their RNA moieties were then recentrifuged on gradients. By this analysis, 27% of the U1 RNA originally bound to hnRNPs was associated with rapidly sedimenting (>30 S) RNA (at 50 mM NaCl) suggesting their association by RNA-RNA hydrogen bonds. When the concentration of NaCl was 500 mM, 31% of the U1 RNA was associated with large RNA. Hence, approximately 30% of the U1 RNA molecules originally bound (or about 15% of the total nuclear U1 RNA) were found to be associated by RNA-RNA hydrogen bonds while the remainder of the binding of U1 RNP to hnRNP was by protein-protein and/or protein-RNA interactions. 相似文献