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141.
Phosphoglycerate mutase and bisphosphoglycerate synthase (mutase) can both be phosphorylated by either glycerate-1,3-P2 or glycerate-2,3-P2 to form phosphohistidine enzymes. The present study uses a rapid quench procedure to determine if, for each enzyme, the formation of the phosphorylated enzyme and phosphate transfer from the enzyme can occur at rates consistent with the overall reactions. With bisphosphoglycerate synthase from horse red blood cells (glycerate-1,3-P2 leads to glycerate-2,3-P2) at pH 7.5, 25 degrees, phosphorylation of the enzyme appears rate-limiting, k = 13.5 s-1, compared with kcat = 12.5 s-1 for the overall synthase rate. Phosphoryl transfer from the enzyme to phosphoglycerate occurs at 38 s-1 at 4 degrees and was too fast to measure at 25 degrees. With chicken muscle phosphoglycerate mutase the half-times were too short to measure under optimal conditions. The rate of enzyme phosphorylation by glycerate-2,3-P2 at pH 5.5, 4 degrees, could account for the overall reaction rate of 170 s-1. The rate of phosphoryl transfer from the enzyme to glycerate-3-P was too rapid to measure under the same conditions. It is concluded that the phosphorylated enzymes have kinetic properties consistent with their participation as intermediates in the reactions catalyzed by these enzymes. 相似文献
142.
143.
S Srimatkandada B I Schweitzer B A Moroson S Dube J R Bertino 《The Journal of biological chemistry》1989,264(6):3524-3528
144.
145.
Tn5-induced tra mutations were localized on the physical map of a broad host range plasmid pBS1001. Mutations were united into three clusters covering 25% of plasmid DNA. They were distributed in 7 groups by complementation analysis. It was shown that coexistence of tra mutants of pBS1001 and RP4 within the same cell did not restore conjugation properties of both plasmids. High frequency mobilization of some known vectors by pBS1001 was demonstrated. 相似文献
146.
I S Sever Z A Dube?kovskaia A F Trofimenko E M Aslanian S V Khachaturian A P Dobritsa 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》1990,(6):24-28
Effects of the structure of plasmids carrying the cloned delta-endotoxin gene (tox) ot Bacillus thuringiensis and of the culture media on the expression of the gene have been studied. The DNA region located upstream from the crystal protein gene promoter inhibited the expression of the tox gene in Escherichia coli cells, but enhanced the expression in Bacillus megaterium cells grown in LB medium. The upstream DNA region did not affect the tox gene expression when Bacillus megaterium cells were grown in SSM medium. 相似文献
147.
148.
N. Kluge G. Gaedicke G. Steinheider S. Dube W. Ostertag 《Experimental cell research》1974,88(2):257-262
A cell clone of erythroleukemic mouse cells transformed by the spleen focus forming virus (SFFV) was adapted to growth in serum-free medium. The cells show induced erythroid differentiation if dimethylsulfoxide (DMSO) and iron are added to the serum-free medium. No serum constituents or macromolecules are required for induced differentiation. Serum enhances the capacity of the cells to differentiate. Erythropoietin is ineffective in promoting erythroid differentiation or an increased rate of cell division. Transferrin is not necessary for transport of iron into these cells. 相似文献
149.
Biswendu B. Goswami Symamalima Chakrabarti Dipak K. Dube S. C. Roy 《The Biochemical journal》1973,134(3):815-816
A mitochondrial system from 48h-germinating seeds of Vigna sinensis (Linn.) Savi is capable of incorporating l-[U-(14)C]valine into proteins and is practically insensitve to cycloheximide, but highly sensitive to chloramphenicol and fusidic acid, a potent inhibitor of peptide-chain elongation factor. A system consisting of mitochondrial S-100 fraction and ribosomes from the same source and other cofactors is capable of polyphenylalanine synthesis and behaves similarly with respect to these inhibitors. 相似文献
150.
The effect of Mn2+, a known mutagen, on the fidelity of DNA synthesis by avian myeloblastosis DNA polymerase has been determined. Substitution of Mn2+ for Mg2+ leads to an enhanced incorporation of noncomplementary deoxynucleotides as well as complementary ribonucleotides with either poly (A) or poly (C) as templates. Since this polymerase lacks any detectable deoxyribonuclease activity, the mutagenic effect of Mn2+ in promoting errors in base-pairing does not result from any diminished proof-reading function. 相似文献