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21.
J. H. M. Hovenkamp-Hermelink E. Jacobsen A. S. Ponstein R. G. F. Visser G. H. Vos-Scheperkeuter E. W. Bijmolt J. N. de Vries B. Witholt W. J. Feenstra 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,75(1):217-221
Summary An amylose-free potato mutant was isolated after screening 12,000 minitubers. These minitubers had been induced on stem segments of adventitious shoots, which had been regenerated on leaf explants of a monoploid potato clone after Röntgen-irradiation. The mutant character is also expressed in subterranean tubers and in microspores. Starch granules from the mutant showed a strongly reduced activity of the granule bound starch synthase and loss of the major 60 kd protein from the starch granules. 相似文献
22.
Activity of key nitrogen assimilating enzymes was studied in developing grains of high-lysine opaque sorghum P-721 and normal
sorghum CSV-5. The higher percentage of protein in opaque sorghum was mainly due to lower starch content since protein per
grain was less than in CSV-5. During grain development, albufn and globulin decreased while prolafne and glutelin increased.
Prolafne content in CSV-5 was higher than in opaque sorghum. Average nitrate reductase activity in flag and long leaf were
similar in both the varieties. The nitrate reductase activity decreased during grain development. Glutamate dehydrogenase
activity was higher during early development and lower at later stages in opaque sorghum than in CSV-5. Glutamate oxaloacetate
transaminase activity was higher and glutamine synthetase lower in opaque sorghum than in CSV-5 grains during development.
Glutamate synthase activity was higher in opaque sorghum up to day 20 and lower thereafter than in CSV-5. It is suggested
that reduced activities of glutamine synthetase as well as glutamate synthase in opaque sorghum as compared to CSV-5 during
later stages of development may restrict protein accumulation in the former. 相似文献
23.
D. Landowne 《The Journal of membrane biology》1987,96(3):277-281
Summary In 10 K artificial seawater (ASW). D2O replacement reduced the Na efflux of squid axons by about one third. In 0 K ASW, D2O replacement had little effect. D2O reduced the K+ sensitivity of the efllux but increased the affinity for K+. A 4° decrease in temperature mimicked the effects of D2O. When axons were injected with arginine, to decrease the ATP/ADP ratio, they lost K+ sensitivity in normal ASW, as expected. Their efflux into 0 K ASW became D2O sensitive. The results are discussed in terms of conformational changes in the Na pump molecular complex. 相似文献
24.
Phosphorylation and Inactivation of Brain Glycogen Synthase by a Multifunctional Calmodulin-Dependent Protein Kinase 总被引:1,自引:1,他引:0
Nobuhiro Inoue Takafumi Iwasa Kohji Fukunaga Yasuhiko Matsukado Eishichi Miyamoto 《Journal of neurochemistry》1987,48(3):981-988
Glycogen synthase was partially purified from canine brain to about 70% purity. The purified enzyme showed differences from the properties of the skeletal muscle enzyme with respect to molecular weights of the holoenzyme and subunit and phosphopeptide mapping. The multifunctional calmodulin-dependent protein kinase from the brain phosphorylated brain glycogen synthase with concomitant inactivation of the enzyme. Although about 1.3 mol of phosphate/mol subunit was maximally incorporated into glycogen synthase, 0.4 mol of phosphate/mol subunit was sufficient for the maximal inactivation of the enzyme. The results indicate that brain glycogen synthase is regulated in a calmodulin-dependent manner similarly to the skeletal muscle enzyme, but that the brain enzyme is different from the skeletal muscle enzyme. 相似文献
25.
S. L. Macaulay Julie D. Newman J. D. Mc Armstrong J. Bornstein 《Molecular and cellular biochemistry》1987,74(1):95-101
The N-terminal part sequences of pituitary growth hormone, N-acetyl-hGH 7–13 and hGH 6–13, promoted conversion of glycogen synthase b to glycogen synthase a in skeletal muscle and adipose tissue when injected intravenously. The peptides also caused conversion of phosphorylase a to phosphorylase b in liver and adipose tissue, but not in muscle, where the peptides antagonised activation of phosphorylase. Synthase phosphatase activity in muscle and phosphorylase phosphatase activity in liver increased after injection of peptide, with time courses of change similar to those seen for muscle synthase and liver phosphorylase activities. Injection of peptide also decreased both the cyclic AMP dependent and independent synthase kinase activities in muscle. These results show that the insulin-like activities of these peptides on glycogen synthase and phosphorylase involve both increases in protein phosphatase activities and inhibition of protein kinase activities. These results are discussed in relation to the insulin-like activities of growth hormone. 相似文献
26.
S. Kauffer R. Schmid K. Steffens G. Deckers-Hebestreit K. Altendorf 《Archives of microbiology》1987,148(3):187-192
The ATP synthase complex of Klebsiella pneumoniae (KF1F0) has been purified and characterized. SDS-gel electrophoresis of the purified F1F0 complexes revealed an identical subunit pattern for E. coli (EF1F0) and K. pneumoniae. Antibodies raised against EF1 complex and purified EF0 subunits recognized the corresponding polypeptides of EF1F0 and KF1F0 in immunoblot analysis. Protease digestion of the individual subunits generated an identical cleavage pattern for subunits , , , , a, and c of both enzymes. Only for subunit different cleavage products were obtained. The isolated subunit c of both organisms showed only a slight deviation in the amino acid composition. These data suggest that extensive homologies exist in primary and secondary structure of both ATP synthase complexes reflecting a close phylogenetic relationship between the two enterobacteric tribes.Abbreviations ACMA
9-amino-6-chloro-2-methoxyacridine
- DCCD
N,N-dicyclohexylcarbodiimide
- FITC
fluorescein isothiocyanate
- SDS
sodium dodecyl sulfate
- TTFB
4,5,6,7-tetrachloro-2-trifluoromethylbenzimidazole 相似文献
27.
P. Pellerin B. Gruson G. Prensier G. Albagnac P. Debeire 《Archives of microbiology》1987,146(4):377-381
An intracellular glycogen was purified and characterized from the acetoclastic bacteria Methanothrix str. FE, its average chain length was about 13 glucose residues. Acetyl-CoA was shown to be synthesized by the action of acetate thiokinase; in addition pyruvate synthase, phosphoenolpyruvate synthetase and enzymes of gluconeogenesis were detected in cell extracts. For glycogen synthase activity, both adenosine diphosphate glucose and uridine diphosphate glucose were used as glycosyl donors, apparent K
m were, respectively, 8 M for ADPGlc and 625 M for UDPGLe, at the opposite the V
m were the same for both precursors. This was in accordance with competition experiments and strongly suggested that only one glucosyl transferase was involved and that ADPGlc was the physiological glycosyl donor in Methanothrix str. FE. In addition branching enzyme activity (1-4-glucan-6-glucosyl transferase) was detected in cell extracts.Abbreviations ADPGlc
adenosine diphosphate glucose
- UDPGlc
uridine diphosphate glucose 相似文献
28.
29.
Three distinct regulatory elements comprise the upstream promoter region of the nopaline synthase gene 总被引:5,自引:0,他引:5
Summary Fine deletion mutants were generated in the upstream control region of the nopaline synthase (nos) promoter to define the position and role of upstream regulatory elements. The results indicated that the 8 bp sequence (CAGAAACC) at -106/-113 and its inverted repeat (GGTTTCTG) at -140/-147 are important for promoter function. The downstream element appears more important than the upstream element since deletion of the former reduced promoter activity more significantly than deletion of the latter. Deletion of the element alone, however, did not abolish promoter function, whereas, deletion of the 10 bp potential Z-DNA-forming (Z) element located between the repeat elements nullified promoter activity. Therefore, it appears that the Z element is an essential upstream regulator and the repeated elements are upstream modulators of the nos promoter. These elements are functionally distinct since alteration of stereospecificity or insertion of short oligonucleotides between the elements did not significantly influence promoter activity. These regulatory elements were unable to function from 200 bp upstream of the CCAAT-TATA box region. 相似文献
30.
The two isoenzymes of NADH-dependent glutamate synthase (NADH-GOGAT; EC 1.4.1.14), previously identified in root nodules of Phaseolus vulgaris L., have both been shown to be located in root-nodule plastids. The nodule specific NADH-GOGAT II accounts for the majority of the activity in root nodules, and is present almost exclusively in the central tissue of the nodule. However about 20% of NADH-GOGAT I activity is present in the nodule cortex, at about the same specific activity as this isoenzyme is found in the central tissue. Glutamine synthetase (GS; EC 6.3.1.2) occurs predominantly as the polypeptide in the central tissue, whereas in the cortex, the enzyme is represented mainly by the polypeptide. Over 90% of both GS and NADH-GOGAT activities are located in the central tissue of the nodule and GS activity exceeds NADH-GOGAT activity by about twofold in this region. Using the above information, a model for the subcellular location and stoichiometry of nitrogen metabolism in the central tissue of P. vulgaris root nodules is presented.Abbreviations Fd-GOGAT
ferredoxin-dependent glutamate synthase
- GOGAT
glutamate synthase
- GS
glutamine synthetase
- NADH-GOGAT
NADH-dependent glutamate synthase
- IEX-HPLC
ion-exchange high-performance liquid chromatography 相似文献