Isolation and characterization of DNA-binding proteins of Yoshida ascites tumour cells

Age-dependent changes in the level of a 34 kDa DNA-binding protein in developing chick embryo liver

The relative amounts of a DNA-binding protein of 34 kDa increased during the early stages of development of chick embryo liver. The content of this protein reached a maximum in 18-19-day-old embryonic livers and decreased afterwards in older embryonic and post-natal chick livers. The 34 kDa polypeptide is the major DNA-binding protein (DBP) of embryonic liver and it preferentially binds to single-stranded DNA. The quantity of the 34 kDa DBP was relatively very low in embryonic muscle, heart and brain.

DNA-binding proteins of human placenta: purification and characterization of an endonuclease

DNA binding proteins present in the cytoplasm and nuclei of term placenta were isolated by DNA-cellulose chromatography and analysed by electrophoresis in high resolution polyacrylamide gradient gels. A denatured DNA specific protein of approximate molecular weight 34 000 daltons was the predominant DNA binding protein of the cytoplasm; this protein consisted of over 65% of the total DNA binding proteins of the 0.15 M NaCl eluate of the cytoplasm. The cytoplasmic extracts contained two additional DNA binding proteins of molecular weight 24 000 and 18 000 daltons and these proteins bound preferentially to ds DNA. All the three DNA binding proteins were also present in the nuclei and electrophoresis of histones in adjacent lanes indicated that they are not histones. The 34 000-dalton DNA binding protein has been purified by ammonium sulphate fractionation followed by phosphocellulose (PC) chromatography. The DBP eluted from the PC column between 0.125-0.15 M potassium phosphate. PC fractions containing electrophoretically pure 34 KD DBP showed an endonuclease activity capable of converting plasmid pBR 322 DNA to the linear form. Maximum endonucleolytic activity was observed in the presence of 3-5 mM Mg2+ and the enzyme activity was completely inhibited by 3 mM ethylenediamine tetraacetate.