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991.
This paper describes an approach to seek for mouse c-Myc/Myn proteins-bound specific sequences among genomic DNA.cDNA fragment of myn gene was obtained through RT-PCR technique from RNA of NIH3T3 cells.DNA fragments encoding BR/HLH/LZ structure of Myc and Myn proteins were cloned in frame into pGEX-2T vector respectively.Fusion GST-Myc and GST-Myn synthesized in E.coli hosts showed affinity to CACGTG E-box DNA and subsequently interacted with genomic fragments prepared through whole-genome-PCR.A PCR-assisted procedure which combines protein-DNA interaction and affinity chromatography was designed to enrich Myc/Myn bound DNA.At least two genomic DNA fragments obtained exhibit specifical binding capacity to Myc/Myn complex but not to GST alone.Significance of the work and of the technique itself as well asidentification of the DNAs are discussed. 相似文献
992.
利用大鼠肝脏线粒体为材料,以琥珀酸为底物,研究了不同浓度的丹参酮Ⅱ-A磺酸钠对线粒体态4、态3呼吸及呼吸控制率,线粒体跨膜电位,线粒体呼吸链复合体(Ⅱ+Ⅲ)电子传递及质子转移活性的影响。结果证明丹参酮ⅡA-磺酸钠是线粒体呼吸链复合体(Ⅱ+Ⅲ)的有效抑制剂。文中对丹参酮ⅡA-磺酸钠在心肌缺血再灌注过程中的保护作用的分子机理进行了讨论。 相似文献
993.
A vestigiferan species commonly referred to as Pyramimonas obovata N. Carter has been redescribed as P. melkonianii sp, nov. Characters of this species and a further six (P. disomata Butcher ex McFadden, Hill et Wetherbee, P. mantoniae Moestrup et Hill, P. mitra Moestrup et Hill. P. moestrupii McFadden, P. aff. nephroidea McFadden, P. orientalis Butcher ex McFadden, Hill et Wetherbee) isolated from South African waters are used to define further the subgenus Vestigifera McFadden. This includes a unique chloroplast shape and basal hyaline region with stellate or cruciform vacuoles, a transitional plate-like structure in the flagellum, and a different microtubular root system. The proximal set of basal body connectives were found to be remarkably symmetrical and like those of the subgenus Trichocystis McFadden, and a duct fibre was found associated with the Id root in all currently investigated species. The validity of the larger body (box and crown) scales as taxonomic markers at a fine level is also questioned. 相似文献
994.
Immunoreactivity of the arginine/aspartic acid (RD) repeats of the 70K protein of U1 small nuclear ribonucleoprotein (snRNP) was determined to be conformationally dependent. The monoclonal autoantibody 2.73, isolated from a lupus-prone MRL/n mouse model, is reactive with the RD repeat regions of U1 snRNP 70K protein. Immunochemical analysis of the antigenic determinants with use of chemically synthesized peptides characterized the 2.73 epitope as the RD repeat [Pelsue, S.,et al. (1993)Autoimmunity,15, 231–236] Analysis by circular dichroism (CD) and nuclear magnetic resonance spectroscopy indicates conformational preferences in the immunoreactive peptides. Computer analyses of CD spectra obtained on the RD-containing peptides predict-turns and-sheet to be the preferred conformations of the RD repeats. This structure was also predicted by the Chou-Fasman algorithm. The RD repeat is believed to be a conserved structural motif; however, the biological function is still unclear. Immunological and biochemical analysis of autoimmune antibodies and their respective antigenic determinants has helped to characterize the possible mechanisms that lead to autoimmune diseases. This is the first report of a conformationally dependent, linear epitope of an autoantibody. 相似文献
995.
To study the mechanism of protein carboxyl methyltransferase-driven repair of age-damaged sites in polypeptides, a modell-isoaspartyl peptide,l-isotetragastrin, was enzymatically repaired to normall-tetragastrin in the presence of18O-enriched water. By this design, the enrichment of18O atoms in the peptide would reflect the number of passages through a hydrolyzable succinimide intermediate during formation of the repaired product. Mass determinations by FAB mass spectrometry revealed repaired peptide with two18O atoms incorporated, demonstrating that more than a single cycle of methylation and demethylation is necessary to ensure stoichiometric repair.Abbreviations HPLC
high-pressure liquid chromatography
- FAB
fast atom bombardment
- TFA
trifluoroacetic acid
- PCM
proteind-aspartyl/L-isoaspartyl carboxyl methyltransfer-ase
-
l-Normal
[l-Asp3]tetragastrin
-
l-Iso
[L-isoAsp3]tetragastrin
-
d-Normal
[d-Asp3]tetragastrin
-
d-Iso
[d-isoAsp3]tetragastrin 相似文献
996.
Eric Dufour Paul Robert Dominique Bertrand Tomasz Haertlé 《Journal of Protein Chemistry》1994,13(2):143-149
Fourier transform infrared spectroscopy has been applied to investigate the secondary structural changes of-lactoglobulin in water/ethanol mixtures. The studies were carried out at two differentpHs and at high protein concentrations. The spectra were recorded using an attenuated total reflection cell. The amide I band of-lactoglobulin in water reveals large amounts of intra extended-sheet structure. About 20% ethanol,-lactoglobulin unfolds and-strand formation is observed.-Helices are built up by increasing the ethanol concentration up to 30%. In 50% ethanol,-lactoglobulin gels providing the apparent pH are neutral. The secondary structural changes of-lactoglobulin were observed on the similarity maps obtained by Principal Component Analysis. 相似文献
997.
In a previous report [Yanget al., (1987a),J. Biol Chem.
262, 7034–7040], a cyclic-AMP- and calcium-independent brain kinase which requires autophosphorylation for activity was identified as a very potent myelin basic protein (MBP) kinase. In this report, the phosphorylation sites of MBP by this autophosphorylation-dependent protein kinase (autokinase) are further determined by two-dimensional electrophoresis/thin-layer chromatography, phosphoamino acid analysis, high-performance liquid chromatography, tryptic peptide mapping, sequential manual Edman degradation, and direct peptide sequencing. Autokinase phosphorylates MBP on both threonine and serine residues. Three major tryptic phosphopeptide peaks were resolved by C18-reversed phase highper-formance liquid chromatography. Sequential manual Edman degradation together with direct sequence analysis revealed that FS(p)WGAEGQKPGFGYGGR is the phosphorylation site sequence (molar ratio 1.0) for the first major phosphopeptide peak. When mapping with bovine brain MBP sequence, we finally demonstrate Ser115, one of thein vivo phosphorylation sites in MBP, as the major site phosphorylated by autokinase, implicating a physiologically relevant role of autokinase in the regulation of brain myelin function. By using the same approach, we also identified HRDT(p)GILDSLGR (molar ratio 0.9) and TT(p)HYGSLPQK (molar ratio 0.8) as the major phosphorylation site sequences in32P-MBP phosphorylated by autokinase, further indicating that -Arg-XSer/Thr-(neutral amino acid)3-(amino acid-containing hydroxyl group such as Ser/Glu/Asp)-(neutral amino acid)2-may represent a unique consensus sequence motif specifically recognized by this autophosphorylation-dependent multisubstrate/ multifunctional protein kinase in the brain. 相似文献
998.
A simple procedure is described for the elimination ofO-linked glycans from bovine submaxillary mucin under non-reducing conditions, using triethylamine in aqueous hydrazine. The glycans were isolated as the hydrazones, which were converted to the reducing glycans by exchange with acetone in neutral aqueous solution. The glycan alditols obtained after reduction corresponded to those obtained by the reductive -elimination ofO-glycans. 相似文献
999.
Mathew A. Maliakal Mepur H. Ravindranath Reiko F. Irie Donald L. Morton 《Glycoconjugate journal》1994,11(2):97-104
In the measurement of total lipid-bound sialic acids involving periodic acid oxidation, as in the periodate-resorcinol assay, the inner sialic acids of disialoglycolipids (such as GD3 and GD2) are not involved because their 2,8 ketosidic linkages are resistant to periodic acid oxidation, even after acid/enzyme hydrolysis or alkali pretreatment. However, the sialic acids from these glycolipids can be recovered completely after cleavage of 2,8 linkages byV. cholerae sialidase in the presence of cholic acid, sodium dodecyl sulphate and calcium. Interestingly, removal of calcium or detergent(s) or both significantly minimizes the sialidase action on the disialyl residues of these gangliosides. Therefore, we recommend sialidase (Vibrio cholerae) pretreatment of the glycolipids in the presence of cholic acid, SDS and Ca2+ for complete recovery of sialic acids from di- and polysialogangliosides and for accurate measurement of total lipid-bound sialic acids by periodate-resorcinol assay.Presented at the Second International Glycobiology Symposium which was held in San Francisco, CA, USA (14 February 1994). 相似文献
1000.
The June 1991 eruption of Mt. Pinatubo in the Philippines produced one of the greatest volcanic aerosols in the last hundred years. The estimated net decrease of radiation may have peaked at 10% in the tropics. What was the impact of the Pinatubo aerosol on regional and global climate? Besides the expected net cooling of the average global surface temperature, correlation studies indicate that other types of climate anomalies may also be expected. These include the appearance of an El Niño event, decreased Indian monsoon rainfall, fewer tropical storms in the north Atlantic Ocean in 1991–1993, and normal to above normal winter rainfall in California in 1991/92, all of which were observed. A proposed physical mechanism for the almost-simultaneous occurrence of this constellation of climate anomalies is presented. The results of correlation studies between low-latitude volcanic aerosols and the El Niño/Southern Oscillation are presented in some detail as one example. The correlation between Indian monsoon rainfall and tropical storms in the north Atlantic Ocean is also shown and is updated for the most recent 5 years. 相似文献