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Biomedical subjects

H Sierakowska

Publications and source records attributed to H Sierakowska.

At least 19 recordsLinked to original sources
PubMed1991

Antinuclear antibody profile in juvenile rheumatoid arthritis.

Immunoblot positive sera from children with juvenile rheumatoid arthritis detected from 1 to greater than or equal to 10 proteins in HeLa nuclear sonicates. Thirty percent of the sera reacted with histone H1. Antibodies to at least 1 of 6 most frequently detected nonhistone proteins were present in 85% of the sera. Using immunopurified antibodies to each of the 6 common antigens, we found that 4 of them were associated with mitotic chromosomes. Most sera detected at least 1 of these 4 nonhistone chromosomal proteins. Fifteen percent of the sera immunoprecipitated ribonucleoproteins; some exhibited a novel specificity, precipitating mature transcripts of RNA polymerase III. When present, antibodies to a 45 kDa protein occur only in sera from children without iritis and not in those with active iritis. Overall, the antibody profiles were highly individual and did not appear to correlate with disease subtype or activity.

Adolescent↗
PubMed1989

Inhibition of pre-mRNA splicing by 5-fluoro-, 5-chloro-, and 5-bromouridine.

Pre-mRNA transcripts of the human beta-globin gene containing 5-fluoro-, 5-chloro-, and 5-bromouridine were tested for splicing in vitro. Pre-mRNA containing 5-fluorouridine was spliced accurately and efficiently in the nuclear extract from HeLa cells, whereas 5-chloro-, and 5-bromouridine containing transcripts were not spliced. Analysis of the splicing reactions by electrophoresis on nondenaturing polyacrylamide gels showed that the latter two transcripts were unable to form active splicing complexes. Treatment of HeLa cell cultures with 5-fluorouridine decreased the splicing activity of the nuclear extracts in a dose- and time-dependent fashion. The decrease in splicing activity of these extracts appears to be due in part to a decreased level of U-2 small nuclear RNA and the corresponding ribonucleoprotein particle, U2-snRNP.

Antiviral Agents↗
PubMed1987

Purification and RNA binding properties of a C-type hnRNP protein from HeLa cells.

A protein of the C group, most likely C3 (Mr approximately 42,000, pI approximately 6, corresponding to IEF 48m,n of the HeLa protein catalogue (Celis, J. E., Bravo, R., Arenstorf, H. P., and LeStourgeon, W. M. (1986) FEBS Lett. 194, 101-109)), a minor hnRNP protein was purified to near homogeneity under nondenaturing conditions from 40 S heterogeneous nuclear ribonucleoprotein particles. Type C protein stoichiometrically disrupts the residual secondary structure of natural and synthetic RNAs, e.g. HeLa hnRNA, coliphage MS2 RNA, and poly(rU)-spermine, and decreases the Tm of duplex structures, e.g. poly[r(A + U)], by about 30 degrees C. Binding of the protein to polynucleotides is not highly cooperative and has a stoichiometry of one protein per about 10 nucleotides. Binding experiments with a variety of synthetic and natural poly- and oligonucleotides, including those containing consensus splice site sequences, indicate that the protein has a high affinity for G-rich and U-rich regions, G-rich regions being preferred. Base analogs I and T have affinities for the protein that are similar to G and U. There is little or no affinity for A- and C-rich regions. The presence of A residues in a G- or U-rich sequence does not interfere with binding while C-rich regions decrease or prevent the binding of the protein. The nucleotide specificity of type C protein, e.g. selective binding to an oligonucleotide from the 3' end of an intron, is discussed in relationship to the abundance of G and U and the relative scarcity of C residues in the processing signals in pre-mRNA.

Circular Dichroism↗
PubMed1986

Antibodies to hnRNP core proteins inhibit in vitro splicing of human beta-globin pre-mRNA.

In vitro splicing of human beta-globin pre-mRNA can be fully inhibited by treatment of the splicing extract with polyclonal antibodies against hnRNP core proteins prior to the addition of pre-mRNA. Inhibition of the first step in the splicing pathway, cleavage at the 5' splice site and lariat formation, requires more antibodies than inhibition of the second step, cleavage at the 3' splice site and exon ligation. The anti-hnRNP antibodies can also inhibit the splicing reaction after the formation of the active nucleoprotein splicing complex which is known to occur during the initial lag period. Thus, hnRNP core proteins appear to be present in the complex that performs pre-mRNA splicing.

Antibody Specificity↗
PubMed1984

Nucleotide pyrophosphatase from potato tubers. Purification and properties.

Purification of potato tuber nucleotide pyrophosphatase (EC 3.6.1.9) has been modified to furnish a rapid and reproducible procedure yielding a preparation purified 1800-fold and homogeneous in sodium dodecyl sulphate/polyacrylamide gel electrophoresis. The Mr of the enzyme, from gel filtration or sucrose density gradient centrifugation, is 343000 or 346000 respectively; and SDS electrophoresis indicates an Mr for the subunit of 74000. Analytical isoelectrofocusing reveals a broad isoelectric range of pH 8.3-8.7. The enzyme is a glycoprotein. The purified enzyme exhibits the previously reported activities versus pyrophosphate linkages located at either the 5'-OH or 3'-OH of nucleosides, and phosphodiester linkages in: (a) aryl esters of nucleoside 3'- and 5'-phosphates, p-nitrophenylphosphate and orthophosphate, and (b) nucleoside cyclic 2',3'-phosphates. However, the relative rates of activity towards these substrates, and the corresponding V values, differ significantly. The enzyme exhibits additional novel activities, including ability to cleave dinucleoside polyphosphates such as A(5')p2(5')A-A(5')p5(5')A, and aryl phosphonates. Contrary to previous reports, there is no activity towards nucleoside cyclic 3',5'-phosphates. The present preparation is also devoid of endonucleolytic activity, so that it specifically cleaves m7GMP from the 5'-terminal m7G(5')p3(5')Gm of intact reovirus mRNA. NAD+ was found to be the most effective inhibitor of enzyme activity versus thymidine 5'-p-nitrophenylphosphate, with a Ki = 0.1 mM. Kinetic analyses demonstrated competitive inhibition between these two substrates. Both 2',3'-cAMP and thymidine 3'-p-nitrophenylphosphate inhibit hydrolysis of NAD+ noncompetitively and vice-versa.

Chromatography, Thin Layer↗
PubMed1978

The cytochemical localization of nucleotide pyrophosphatase activity in plant tissues using naphthyl esters of thymidine-5'-phosphate.

A cytochemical method for the localization of nucleotide pyrophosphatase activity in plants employing naphthol AS-BI thymidine 5'-monophosphate and alpha-naphthyl thymidine 5'-monophosphate as specific substrates is reported. Biochemical evidence for the validity of this method is presented and the synthesis of the naphthol AS-BI ester is described. The application of this cytochemical technique to shoots of Triticum sp. and roots of Vicia faba has shown nucleotide pyrophosphatase to be ubiquitous in its distribution in these organs and to occur in a structurally-bound form in the cytoplasm. The highest activity was detected in developing fibres adjacent to the leaf vascular bundles, in the coleoptile epidermal and hypodermal cells and in the coleoptile and leaf xylem.

Chemical Phenomena↗
PubMed1977

Removal of 5'-terminal m7G from eukaryotic mRNAs by potato nucleotide pyrophosphatase and its effect on translation.

The procedure for isolation of nucleotide pyrophosphatase (E.C. 3.6.1.9.) from potato has been modified to yield an endonuclease-free preparation purified 2300-fold. The enzyme was used for specific cleavage of pyrophosphate linkages in the 5'-terminal cap (m7GpppN) of several eukaryotic messenger RNAs. Enzymatic removal of 5'-terminal pm7G from reovirus, rabbit globin and Artemia salina mRNAs resulted in an almost complete loss (greater than 80%) of their template activities in a cell-free protein synthesizing system from wheat germ. Incubation with nucleotide pyrophosphatase did not decrease the translation of phage f2 RNA in an Escherichia coli cell-free system.

Animals↗
PubMed1976

Human pancreatic-type ribonucleases with activity against double-stranded ribonucleic acids.

Purified acid-thermostable ribonuclease (Ribonucleate 3'-pyrimidino-oligonucleotidohydrolase, EC 3.1.4.22) from human pancreas degrades double-stranded RNA at 2% the rate for single-stranded RNA. The activities against single-stranded RNA and double-stranded RNA were shown to be due to a single enzyme with properties similar to bovine pancreatic RNAase A. For purposes of comparison the activities against double-stranded RNA of crystalline ribonucleases of the whale, rat and cow were assayed and found to be 0.4%, 0.03% and 0.003%, respectively, of their activities against single-stranded RNA. Both human serum and urine contain RNAse components of pancreatic origin which hydrolyze double-stranded RNA at 2% and 0.4%, respectively, of the rates against single-stranded RNA. By contrast, purified acid-thermostable RNAases from human spleen and liver hydrlyze double-stranded RNA at least 20-fold more slowly than human pancreatic RNAase, relative to the corresponding rates against single-stranded RNA. The human pancreatic and serum enzymes exhibit appreciable activity against the poly(C) component of the double-stranded poly(I)-poly(C); they also attack poly(C) itself at approximately 25 times the rate for poly(U) and at more than 50 times the rate for single-stranded RNA.

Animals↗
PubMed1976

Novel activity of potato nucleotide pyrophosphatase.

The classical Kornberger-Pricer procedure for purification of potato nucleotide pyrophosphatase (EC 3.6.1.9) has been modified to yield a preparation purified 2500-fold. In addition to the known activity against pyrophosphate linkages in pyrophosphates located at the 5'-OH of nucleosides, and phosphodiester linkages in aryl esters of nucleoside-5'-phosphates, the enzyme has now been shown to catalyze the cleavage of: (a) aryl esters of nucleoside-3'-phosphates and orthophosphates, (b) nucleotide pyrophosphate linkages of the type (3')-pp-(3'), and (c) pm7G from m7GpppGm-terminated fragments of viral mRNA. Activities against aryl esters of nucleoside-3'- and 5'-phosphates, and NAD, were shown to be due to the same protein by three criteria: (a) constant ratio of activities during purification and gel electrophoresis, (b) identical chromatographic properties in various systems, and (c) similarities in pH-dependence, heat inactivation, and the effects of cations and other substances. Since potato nucleotide pyrophosphatase does not exhibit exonuclease or phosphatase activities against natural substrates for the latter enzymes, but does cleave synthetic aryl esters of nucleotide-3'- and 5'-phosphates and of orthophosphate, it follows that these substrates are not suitable for detection of such activities in higher plants.

Hydrogen-Ion Concentration↗