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Biomedical subjects

M N Thang

Publications and source records attributed to M N Thang.

At least 73 records · Page 4Linked to original sources
PubMed1977

Binding of mouse interferon to polynucleotides.

The polynucleotides poly(I) and poly(U), and to a lesser extent poly(G), are capable of desorbing mouse interferon from blue dextran-Sepharose columns, whereas poly(A) andpoly(C) are without effect. When covalently bound to agarose, poly(I), poly(U), and also poly(A) act as potent ligands for purification of interferon by affinity chromatography. Furthermore, poly(I) and poly(U) confer a significant degree of protection to interferon against thermal denaturation. Taken together, these observations point to a direct interaction of interferon with these polymers and suggest that interferon molecules have a polynucleotide attachment site. Possible implications for the concept of interferon induction are discussed.

Cell Line↗
PubMed1977

Poly-2'-deoxy-2'-fluoro-cytidylic acid: enzymatic synthesis, spectroscopic characterization and interaction with poly-inosinic acid.

The polymerization of 2'deoxy-2'-fluoro-cytidine-diphosphate (dCflDP) by polynucleotide phosphorylase is barely detectable in the presence of Mg++ under usual experimental conditions for polymerization of nucleoside diphosphates. High concentrations of enzyme have to be used to accomplish the synthesis. Mn++ is a better activator than Mg++ for the reaction. cCflDP inhibits the polymerization of CDP and has a Km=8.8X10-3M, six times higher than CDP.- The polymer, poly (dCfl), ressembles in many respects poly(C), but not poly(dC): the acid selfstructure forms at similar pK's; interaction with poly(I) yields a 1:1 complex the CD spectrum of which is similar to that of poly(I).poly(C). Finally, the Tm's of poly(I).poly(dCfl) are comparable to those of poly(I).poly(C).

Circular Dichroism↗
PubMed1975

Biosynthesis of mouse interferon by translation of its messenger RNA in a cell-free system.

A fraction of mouse RNA containing messenger RNA coding for mouse interferon was translated with high efficiency in a wheat germ system into a fully active product. This product fulfills the criteria for mouse interferon, namely: (1) it was active against vesicular stomatitis virus and herpes simplex virus in mouse cells; (2) its antiviral activity was species specific; (3) its activity was completely neutralized by mouse anti-interferon serum. The synthesis of interferon in this cell-free system requires the presence of spermine.

Antigen-Antibody Reactions↗
PubMed1975

No correlation between native and denatured forms of tRNA(Trp) form Escherichia coli and the resistant and sensitive molecules characterised by phosphorolysis. Two classes of conformation characterised by phosphorolysis in both native and denatured tRNA(Trp).

Some tRNA molecules in solution are sensitive to attack by polynucleotide phosphorylase while others are resistant, even with pure species of tRNA. Further analysis of this behaviour has revealed an underlying microheterogeneity in tRNA structure. In order to clarify the relation between the sensitive and resistant classes of tRNA, and the native and denatured forms with respect to amino acid acceptance, the phosphorolysis of tRNATrp from Escherichia coli has been investigated. Native tRNATrp is similar to species examined previously: resistant and sensitive classes are observed and the sensitive proportion increases with temperature. At 20 degrees C both native and denatured tRNATrp are stable under phosphorolysis conditions, and denaturated tRNATrp is found also to possess resistant and sensitive classes. About 10% of both native and denatured tRNATrp is rapidly phosphorolysed at 20 degrees C, but the rate of conversion of resistant denatured tRNATrp to the sensitive class is about twice as fact as for the native form. Thus it can be concluded that the sensitive molecules of tRNATrp attacked by polynucleotide phosphorylase are not due to denaturation.

Drug Stability↗
PubMed1975

Properties of a cytoplasmic proteolytic enzyme from Escherichia coli.

A cytoplasmic protease was partially purified from Escherichia coli; its sedimentation coefficient was found to be 5.3 S. This enzyme (which we call protease A) is not a serine protease and cysteine is not required for its activity; it is only active in the presence of divalent ions which are strongly bound to it. After inactivation of protease A by incubation at 50 degrees C in the presence of 1 mM EDTA, the enzyme is reactived by Mg2+, Mn2+ or Ca2+. We have tried most of the usual esters as substrates and found that none was hydrolyzed by the enzyme which induces a highly restricted specificity.

Calcium↗