S Haq

Publications (2)7.14 Total impact

• Article: Purification, characterization, and cDNA cloning of a galactose-specific C-type lectin from Drosophila melanogaster.

  S Haq, T Kubo, S Kurata, A Kobayashi, S Natori
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  ABSTRACT: We purified a lectin from a pupal extract of Drosophila melanogaster. This lectin agglutinated trypsinized and glutaraldehyde-fixed bovine red blood cells in the presence of calcium or magnesium. The hapten sugar of this lectin was galactose. The molecular mass of the intact lectin was determined to be 41 kDa, and it comprised 14- and 17-kDa subunits. The 17-kDa subunit was shown to be a glycosylated form of the 14-kDa subunit. Analysis of the cDNA for this lectin revealed that the 14-kDa subunit consists of 163 amino acid residues and contains all residues conserved in various C-type lectins. It was suggested that the Drosophila lectin and Sarcophaga lectin share some properties and function similarly in defense and development, but probably they are not structural homologues.
  Journal of Biological Chemistry 09/1996; 271(33):20213-8. · 4.77 Impact Factor
• Article: Heat-induced DNA relaxation in vitro by mouse DNA topoisomerase I in the presence of ethidium bromide.

  S Haq, S Natori, K Sekimizu
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  ABSTRACT: In general, covalently-closed circular DNAs that are relaxed by DNA topoisomerase I at higher temperatures are more negatively (or less positively) supercoiled when analyzed at the same temperature. We found that in the presence of ethidium bromide the reaction products were less negatively supercoiled at higher temperatures. Consequently, the linking number of substrate DNA changed reversibly with temperature-shift: DNA relaxation occurred on temperature shift-up, and re-supercoiling on temperature shift-down. Analyses of the migration of covalently closed circular DNA on agarose gel electrophoresis and of the fluorescence intensity of ethidium bromide bound to DNA indicated decrease in binding of the drug to DNA at higher temperatures. Thus, the thermal effects on the topology of the reaction products of mouse DNA topoisomerase I in the presence of ethidium bromide can be explained by the temperature-sensitive interaction of the drug with DNA.
  Journal of Biochemistry 06/1993; 113(5):620-4. · 2.37 Impact Factor