Purification and properties of DNase γ from apoptotic rat thymocytes
نویسندگان
چکیده
We previously identified three distinct DNA endonucleases, DNases α, β and γ, present in rat thymocyte nuclei. On the basis of their enzymic and biochemical properties, γ-type DNase was regarded as a candidate for the apoptotic endonuclease. Here we purified DNase γ to apparent homogeneity from apoptotic rat thymocyte nuclei induced by X-irradiation and characterized its properties in detail. The purified DNase γ exhibited one predominant protein band on SDS}PAGE and an endonuclease activity in a zymography with an estimated molecular mass of 33 kDa. The molecular mass of the native form determined by G2000SW gel-filtration HPLC was 30 kDa. Amino acid analysis showed that the amino acid composition of DNase γ was similar to that of rat DNase I (molecular mass 32 kDa) but different with regard to alanine and lysine residues. The N-terminal amino acid sequence of DNase γ was revealed to be not identical with that of rat DNase I. In accordance with previous studies,
منابع مشابه
Molecular cloning and expression of a cDNA encoding an apoptotic endonuclease DNase gamma.
An endonuclease named DNase gamma has been purified from the nuclei of apoptotic rat thymocytes [Shiokawa, Ohyama, Yamada and Tanuma (1997) Biochem. J. 326, 675-681]. Here we report the molecular cloning of a cDNA encoding a 35 kDa precursor protein for rat DNase gamma. A 1.6 kb mRNA coding for the DNase gamma precursor is detected at high levels in spleen, lymph nodes, thymus and liver. By usi...
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