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1.
Gabriele Mezzetti Mariastella Moruzzi Maria G. Monti Giorgio Piccinini Bruno Barbiroli 《Molecular and cellular biochemistry》1985,66(2):175-183
Summary A cyclic nucleotide-independent protein kinase which phoshorylates preferentially acidic proteins such as casein or phosvitin was isolated from cytosol of chick duodenal mucosa. The enzyme was purified more than 633 fold to apparent homogeneity by ammonium sulfate fractionation, column chromatography on DEAE-cellulose, phosphocellulose, hydroxylapatite and by sucrose density gradient centrifugation. The native enzyme has a molecular weight of 131000 as measured by gel filtration. The enzyme is a complex protein containing three polypeptides of molecular weight of 39 000, 36 000 and 27 000. It behaves as a complex throughout its purification and gel filtration but its components are readily separated by electrophoresis in denaturing buffer. The 27 000 molecular weight band was selectively autophosphorylated when the enzyme was incubated in the presence of [-32P]ATP.When casein was used as substrate, physiological concentrations of naturally occurring polyamines such as spermine and spermidine markedly stimulated enzyme activity. However with phosvitin as substrate polyamines were strong inhibitors of the enzyme activity. This contrasting effect on intestinal kinase activity was also apparent using cytoplasmic proteins as endogenous phosphate acceptors. A characterization of this differential effect is presented and some possible physiological implications are discussed. 相似文献
2.
Gabriele Mezzetti Mariastella Moruzzi Giorgio Piccinini Maria G. Monti Bruno Barbiroli 《Molecular and cellular biochemistry》1986,70(2):141-149
Summary Chick duodenal mucosa contains an endogenous factor which is capable to inhibit selectively a homologous polyamine-sensitive protein kinase. The inhibitor was partially purified and characterized, and it was found to contain typical mucopolysaccharidic components.Glycosidases digestion studies, selective degradation analysis and spectrophotometric titrations with metachromatic dyes indicated that the inhibitor preparation contained two major moieties identified as heparin-like and heparan sulfate-like structures. In chick intestine the inhibitor was specific for polyamine-sensitive protein kinase since selectively interacted with it and was inert towards other cAMP-independent and cAMP-dependent protein kinases. The inhibitory effect of the endogenous factor was counteracted by naturally occurring polyamines such as spermine. The order of potency of various polyamines was: spermine > thermine spermidine diamines. The release of inhibition by addition of physiological concentrations of spermine was also apparent when using cytosolic proteins as endogenous phosphate acceptors. These results suggest that a possible role of polyamine in the regulation of polyamine-sensitive protein kinase in the intestine is to protect the enzyme from the inhibitory action of endogenous heparinoids. 相似文献
3.
Diurnal rhythmicity of mammalian DNA-dependent RNA polymerase activities I and II: dependence on food intake 总被引:3,自引:0,他引:3
B Barbiroli M S Moruzzi M G Monti B Tadolini 《Biochemical and biophysical research communications》1973,54(1):62-68
Diurnal variations of DNA-dependent RNA polymerase activities I and II have been found in rats maintained under controlled feeding schedules. RNA polymerase I has two peaks of activity in a 24-hours cycle: one 6 hours after the onset of dark period and a second one in the middle of the light period. Polymerase II shows only one peak coinciding with the first one of polymerase I. These diurnal fluctuations are not present in the liver of rats denied food on the day of the experiment. Both polymerases do not exibit different optima for divalent metal ions and ionic strength in the different feeding conditions studied. 相似文献
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Trond P. Leren Kari Solberg Olaug K. Rødningen Oddveig Røsby Serena Tonstad Leiv Ose Kåre Berg 《Human genetics》1993,92(1):6-10
DNA from 40 unrelated familial hypercholesterolemia (FH) heterozygotes were subjected to analyses of single-strand conformation polymorphisms (SSCPs) of exon 10 of the low density lipoprotein receptor (LDLR) gene. Four different SSCP patterns were observed. The underlying mutations were characterized by DNA sequencing. Three of the patterns represented the three genotypes of a recently described sense mutation in codon 450. A method based upon the polymerase chain reaction (PCR) was developed to analyze this mutation. The frequencies of the wild-type (G at nucleotide 1413) and mutant (A at nucleotide 1413) alleles were 0.56 and 0.44, respectively. The fourth pattern was found in only one FH heterozygote and was caused by heterozygosity at nucleotide 1469 (G/A). Nucleotide 1469 is the second base of codon 469Trp(TGG). The GA mutation changes this codon into the amber stop codon, and is referred to as FH469Stop. The mutant receptor consists of the amino terminal 468 amino acids. Because the truncated receptor has lost the membrane-spanning domain, it will not be anchored in the cell membrane. FH469Stop destroys an AvaII restriction site, and this characteristic was used to develop a PCR method to establish its frequency in Norwegian FH subjects. Two out of 204 (1%) unrelated FH heterozygotes possessed the mutation. 相似文献
8.
Fiorito Serena Collevecchio Chiara Epifano Francesco Genovese Salvatore Palumbo Lucia 《Phytochemistry Reviews》2023,22(1):73-84
Phytochemistry Reviews - Oxyprenylated secondary metabolites of plant, fungal, and microbial origin have emerged as biologically active natural compounds with a great potential for the next future.... 相似文献
9.
Dissociated cells of middle-to-late blastulae were exposed to 0.1 mg colchicine/ml and achieved 92% metaphase arrest. These cells contained a haploid set of Bombina maxima (Anura:Discoglossidae) chromosomes. When transplanted into the enucleated eggs of B. orientalis, some donor cells stimulated development to the late blastula and middle gastrula stages. — Most (17/20) of the embryos resulting from chromosomal transplantation were nonmosaic aneuploids. A high percentage of recipient egg enucleation (93%), the ratio of long-to-short chromosomes, and the presence of species-specific marker chromosomes proved that chromosomes were transplanted from the donor cells. Therefore, metaphase chromosomes lacking intact spindle apparatuses were injected into and incorporated by amphibian eggs. These chromosomes were replicated in all cells of the resulting embryos. The aneuploidy of these embryos is explained by an inability of the recipient egg to locate and replicate many transplanted chromosomes (44%) before first cleavage. 相似文献
10.
G. Mezzetti M.S. Moruzzi B. Barbiroli 《Biochemical and biophysical research communications》1981,102(1):287-294
The spermine-binding activity of a cytosol protein fraction from chick duodenal mucosa changes in relation to the circulating level of 1,25-dihydroxycholecalciferol. The spermine-binding activity increases very rapidly within 1–2 hours after the rachitic chick was dosed intracardially with 1,25-dihydroxycholecalciferol. The clear and reproducible response is prevented by actinomycin D and cycloheximide. This increase is one of the earliest events induced by the active form of vitamin D3 in the duodenal cell of rachitic chicks. 相似文献