Biomedical subjects

M B Jucá

Publications and source records attributed to M B Jucá.

4 recordsLinked to original sources

PubMed1997

Bovine kidney low molecular weight acid phosphatase: FMN-dependent kinetics.

A low molecular weight bovine kidney acid phosphatase, electrophoretically homogeneous and with a relative molecular mass of 17.8 kDa, was used in this work. Among the various substrates tested, FMN was found to be the most effective, at pH 7.0. Distinct activation energy values were obtained for p-nitrophenyl phosphate- (45.44 kJ mol-1) and flavin mononucleotide- (28.60 kJ mol-1) hydrolysis reactions. The FMN hydrolysis was strongly inhibited by Cu2 and pCMB, but activated by guanosine. Pyridoxal-phosphate and vanadate were competitive inhibitors for the FMN-dependent reaction.

Acid Phosphatase↗

PubMed1995

Inhibition of poly(2'-fluoro-2'-deoxyadenylic acid)-directed-reverse transcriptase activity.

Some intercalating and nonintercalating drugs have been tested as inhibitors on the DNA synthesis reaction catalyzed by avian myeloblastosis virus (AMV) reverse transcriptase, in the presence of polyriboadenylic acid (poly(rA)) and poly(2'-fluoro-2'-deoxyadenylic acid) (poly(dAfl)) as templates. In both cases, the inhibition was higher with the intercalating drug ethidium bromide than with the nonintercalating analog tetramethyl ethidium bromide. Ethidium bromide inhibited more efficiently the poly(rA)- than the poly(dAfl)-directed reverse transcriptase reaction; in the latter case, the inhibition was non-competitive in relation to TTP. On the other hand, the reaction catalyzed in the presence of the 2'-fluorinated polynucleotide as template was inhibited to a higher extent by other nonintercalating drugs, berenil, netropsin, and distamycin. The inhibitions of both reactions by dideoxy TTP, novobiocin and HPA-23 are also discussed.

DNA↗

PubMed1995

Effect of dimethyl sulfoxide on reverse transcriptase activity.

At low concentrations, dimethyl sulfoxide (DMSO) stimulated the avian myeloblastosis virus reverse transcriptase activity. About 40% stimulation was obtained in the presence of 5% (v/v) DMSO, using activated DNA and polyriboadenylic acid (poly(rA)) as templates, and Mg2+ as divalent cation. A similar stimulation by DMSO was observed with Mn2+ for the poly(rA)-dependent reverse transcriptase activity. DMSO at concentrations higher than 15% inhibited the reverse transcriptase reactions, independent of the template-primers used. An exception was detected with the 2'-fluoro analog of poly(rA) as template, where an activation of 100% was found in the presence of 20% DMSO. The stimulation caused by DMSO could be due to a reduction of the apparent Km value for poly(rA) from 9.1 to 3.3 micrograms/ml.

Avian Myeloblastosis Virus↗

PubMed1993

Inhibition of the wheat germ DNA polymerase A activity by the antiviral drug HPA-23.

Wheat germ DNA polymerase A, a gamma-like enzyme, recognized efficiently natural and synthetic RNA templates, resembling a retroviral reverse transcriptase (P. Laquel et al., Biochim Biophys Acta 1048 (1990): 139-148). Ammonium-21-tungsto-9-antimoniate (HPA-23), an antiviral drug, inhibited the DNA polymerase A activities, independently of the template primers used, i.e. activated DNA or polyriboadenylic acid oligodeoxythymidylate (poly(rA)-oligo(dT)). The inhibition observed in the poly(rA)-oligo(dT)-directed DNA polymerase A activity occurred in the presence of either Mg2+ or Mn2+ as divalent cation, and also with the 2'-fluoro analogue of poly(rA) as template. HPA-23 was a non-competitive inhibitor with respect to TTP, activated DNA, poly(rA)-oligo(dT), and poly(dAfl)-oligo(dT). A preincubation study showed a reversible HPA-23 binding to DNA polymerase A, in the presence of poly(rA)-oligo(dT) as the template primer.

Antimony↗