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Biomedical subjects

S A Rasool

Publications and source records attributed to S A Rasool.

6 recordsLinked to original sources
PubMed2001

Production, purification and some properties of Bac201, a bacteriocin-like inhibitory substance produced by Staphylococcus aureus AB201.

Staphylococcus aureus AB201, a clinical isolate from wound pus, produced a bacteriocin-like inhibitory substance termed as Bac201, that was inhibitory to Streptococcus agalactiae, Enterococcus faecalis, Acinetobacter calcoaceticus, Neisseria meningitidis and a number of staphylococcal species. It was purified to homogeneity by ammonium sulfate precipitation, gel filtration (BioSil-SEC-125), and reversed-phase high performance liquid chromatography (Vydac C4). The native Bac201 was sized at approximately 170-kDa as determined by GF HPLC. Fraction-I (native Bac201), having antibacterial activity was also examined by transmission electron microscopy and appeared as globular structure showing resemblance with phage-like objects. The purification of Bac201 resulted in 466-fold increase in specific activity and recovery of 0.94% of total antibacterial activity. The purified Bac201 migrated as single band on SDS-PAGE with an estimated molecular mass of about 41-kDa. Bac201 was sensitive to proteolytic enzymes, resistant to heat and organic solvents, and active over a wide range of pH (2.5-10). The amino acid composition revealed a general resemblance with other reported high molecular mass bacteriocins and predominance of glycine (39%), proline (13%) and alanine (8%) residues. Further results showed that Bac201 has a bactericidal effect on sensitive cells which is not produced by either cell lysis or apparent loss of membrane permeability.

Amino Acids↗
PubMed1999

Isolation and partial characterization of Bac201: a plasmid-associated bacteriocin-like inhibitory substance from Staphylococcus aureus AB201.

Staphylococcus aureus AB201, a clinical isolate from wound pus, produced a bacteriocin-like inhibitory substance termed as Bac201 that exhibited a broad-spectrum activity against both gram-positive as well as gram-negative bacteria. Among gram-negative bacteria it was active against Neisseria meningitidis and Acinetobacter calcoaceticus both being gram-negative cocci. Inhibition due to the effect of organic acids, hydrogen peroxide, or bacteriophages was excluded. This inhibitory substance could not be induced or eluted. It was partially purified to 80% saturation by ammonium sulfate precipitation resulting in maximum specific activity of 829 AU/mg (25-fold increase). Proteolytic enzymes rapidly inactivated the antagonistic activity of the partially purified material, whereas glycolytic and lipolytic enzymes had no effect. It remained stable in the presence of mild organic solvents. It could be stored at -20 degrees C without loss of activity, stable at 60 degrees C and 80 degrees C for 30 min, 100 degrees C for 20 min and autoclaving temperature (121 degrees C for 15 min), and exhibited activity within a wide range of pH (2.5-10). Bac201 had an estimated M(r) of 41kDa, as indicated by activity detection after SDS-PAGE. Temperature-mediated (44 degrees C) plasmid curing studies suggested linkage of bacteriocin production to a 4.8 MDa plasmid. The Bac201 was bactericidal rather than bacteriolytic.

Bacteriocins↗
PubMed1992

DNA repair, cancer and gene therapy.

Fidelity of DNA synthesis is pivotal to our understanding of fundamental biological processes. An organism must replicate and repair its DNA with high accuracy and precision in order to maintain its genetic activity. DNA repair pathways enable cells to offer enhanced resistance to deleterious effects of chemicals and radiations (Lindahl, 1982). A number of pathways have been described e.g. the error-prone SOS repair (that lacks fidelity of repair process),the error-proof adaptive repair of alkylated DNA and inducible response to oxygen radical damage in DNA. These different circuits are under positive regulatory controls. However, the biochemical strategies employed to generate specific protein activators differ among the pathways. Although, the universally occurring repair activities seem to serve efficiently to counteract malignancy, error-prone polymerase and plasminogen activator have been instrumental in tumorigenesis, the process that proceeds by cascading of genetic errors (Sancar and Sancar, 1988).

Journal Article↗
PubMed1990

Nitrosoguanidine-induced adaptive repair in Pseudomonas aeruginosa.

Error-proof adaptive repair has been demonstrated in Pseudomonas aeruginosa. Cells of actively replicating wild-type Ps. aeruginosa (ATCC27853) and its auxotrophic derivative PAO 286 were subjected to stepwise adaptation (up to 1 microgram ml-1) by nitrosoguanidine (MNNG). Such cells resisted lethal and mutagenic effects of MNNG-challenge (lethal) doses more efficiently than those of nonadapted cultures. Similarly, reactivation of alkylated Pseudomonas phages was enhanced in adapted cells only. Induction of adaptive repair enzymes was sensitive to chloramphenicol (protein synthesis-inhibiting antibiotic) during adaptation treatment only. Protein extract from adapted cells showed increased levels in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE).

Adaptation, Physiological↗
PubMed1987

Genetic activity of trimethoprim in the Salmonella/microsomal screening system.

Trimethoprim, a widely used antibacterial drug was tested for its mutagenic potential in the Ames Salmonella/microsomal test system. The results indicated that, when used in the recommended dose range, the drug produced a several-fold increase in the reversion mutations on his(-)----his+ marker in some of the tester strains, compared with the spontaneous reversions. Dose-dependent curves were also obtained for reversion mutations caused by the drug. Ethyl methanesulfonate and benzo[alpha]pyrene were used a control mutagens.

Animals↗