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71.
Rifampin and chloramphenicol inhibited the synthesis of collagenase of Streptomyces sp. A8, suggesting de novo synthesis. The collagenase was induced by insoluble collagen, its macromolecular fragments, gelatin, peptone, hide powder and yeast extract. Growth as well as collagenase synthesis were dependent on substrate availability. Purification of collagenase by DEAE-cellulose chromatography resulted in approximately 25-fold increase in activity (268.6 μmol glycine equivalents min?1 mg?1 protein) relative to the activity of the culture filtrate (10.5 μmol glycine equivalents min?1 mg?1 protein). 相似文献
72.
Y. Chandra Sekharudu V.S.R. Rao 《International journal of biological macromolecules》1984,6(6):337-347
The possible modes of binding for , , , and to concanavalin A have been investigated using theoretical methods. All these sugars, except , reach the active site of concanavalin A with a highly restricted number of binding orientations. Present investigations suggest that the failure of to bind to concanavalin A is not so much due to steric factors as to repulsive electrostatic interactions. can bind to concanavalin A in one mode whereas the other sugars can bind in more than one mode. The high potency of over is mainly due to the possibility of hydrophobic interactions of the α-methoxy group with Leu(99) or Tyr(100) and also due to the possibility of formation of better and more hydrogen bonds with the protein. A comparison of these data with those for the d-glucopyranosides suggests that the change of the hydroxyl at the C-2 atom from equatorial to axial orientation increases the stereochemically allowed region as well as the possible binding modes. From these studies it is also suggested that the overall shape of the oligosaccharides rather than the terminal or internal mannose alone affects the binding potency of saccharides to concanavalin A. 相似文献
73.
The possible modes of binding for methyl-α-d-mannopyranoside, methyl-β-d-mannopyranoside, 2-O-methyl-α-d-mannopyranoside, methyl-2-O-methyl-α-d-mannopyranoside and methyl-α-d-N-acetylmannosamine to concanavalin A have been investigated using theoretical methods. All these sugars, except methyl-α-d-N-acetylmannosamine, reach the active site of concanavalin A with a highly restricted number of binding orientations. Present investigations suggest that the failure of methyl-α-d-N-acetylmannosamine to bind to concanavalin A is not so much due to steric factors as to repulsive electrostatic interactions. Methyl-2-O-methyl-α-d-mannopyranoside can bind to concanavalin A in one mode whereas the other sugars can bind in more than one mode. The high potency of methyl-α-d-mannopyranoside over methyl-β-d-mannopyranoside is mainly due to the possibility of hydrophobic interactions of the α-methoxy group with Leu(99) or Tyr(100) and also due to the possibility of formation of better and more hydrogen bonds with the protein. A comparison of these data with those for the d-glucopyranosides suggests that the change of the hydroxyl at the C-2 atom from equatorial to axial orientation increases the stereochemically allowed region as well as the possible binding modes. From these studies it is also suggested that the overall shape of the oligosaccharides rather than the terminal or internal mannose alone affects the binding potency of saccharides to concanavalin A. 相似文献
74.
Prolific shoot bud differentiation was induced in callus and suspension cultures of hypocotyl origin in Brassica campestris cv. Yellow Sarson on MS medium supplemented with K (13.9–23.2 M) or BA (13.3–22.1 M). Plantlets were obtained by rooting the in vitro differentiated shoots. Histological studies revealed a unique mode of meristemoid formation.Abbreviations MS
Murashige and Skoog (1962)
- 2,4-D
2,4-dichlorophenoxyacetic acid
- BA
Benzyladenine
- IAA
Indole-3-acetic acid
- IBA
Indolebutyric acid
- K
Kinetin
- NAA
Naphthalene acetic acid 相似文献
75.
The rates of Cl? absorption and HCO?3 secretion were not different in turtle urinary bladders bathed in Na+-containing and solutions.These results in turtle bladder are inconsistent with Na+-anion cotransport but can be accounted for by a Cl?/HCO?3 exchange system. 相似文献
76.
Glutamine synthetase I fromRhizobium meliloti was found to be inhibited by adenosine 5-monophosphate, alanine, glycine, carbamyl phosphate, cytidine 5-triphosphate, tryptophan, histidine, and glucosamine-6-phosphate. Each inhibitor was independent in its action and the effect was cumulative when more than one inhibitor was added. 相似文献
77.
Precipitation of charged particles in a tube by their own space charge is investigated theoretically, when the number density
of the particles is large enough so that the potential is a smooth function given by Poisson’s equation, and when the number
density is small so that only the image force is important. These two approaches have been applied to the data given by Weibel
for the human lung, to determine the deposition probabibilities at different generations for submicron particles when the
particle density is 1×105 particles/cm3. The results indicate that the electrostatic dispersion can only lead to a small effect on the lung deposition, the predominant
effect is due to the image force exerted on the particles. 相似文献
78.
79.
80.
Callus cultures of two cultivars of Vigna aconitifolia (IPCMO-926, RDM-120) were raised and their growth and differentiation studied. In IPCMO-926 callus cultures, numerous shoot buds differentiated on MS medium with BA (0.4–22.2 μM) alone or in combination with IAA (5.7 μM). In RDM-120 best differentiation of shoot buds was observed on a medium with K (23.2 μM) and IAA (5.7 μM). Kinetin alone, however, induced rhizogenesis in callus cultures. In suspension cultures of IPCMO-926 embryoids differentiated on MS medium with K (0.5 μM) and 2,4-D (0.4 and 0.9 μM). 相似文献