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KMID : 0371619870030020303
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Journal of Wonkwang Medical Science
1987 Volume.3 No. 2 p.303 ~ p.311
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Properties of Two Distinct Histone Specific Protein Lysyl N-Methyltransferases of Lymphocytes from Balb/c Mouse Spleen
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Abstract
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Invetigations were made to compare the properties of protein lysyl N-methyltransferases located either in cytosol or in nuclear fraction of lymphocytes of Balb/c mouse spleen.
1) The optimum pH of the enzymes in the nuclear fraction was at around 9.0--9.4,while that of the cytosolic fraction was at around 8.2.
2) The enzymes from both fractions were heat-labile, nuclear one showing more lability.
3) Among the proteins investigated, only histones served as substrate to both enzymes but cytochrome C, lysozyme or r-globulin were non-substrate indicating that these enzymes were histone specific protein lysyl N-methyltransferases.
4) Both enzymes were completely inhibited by the prescence of either Cu´´ or He at 2mM concentrations, while the nuclear enzyme was more sensitively inhibited by low concetrations of Cu= (10^-100 pM ). On the other hand. Fes´ brought a partial inhibition on the nuclear enzyme and on the cytosolic enzyme at 2mM concentrations.
5) The apparent Michaelis-Menten constant for S-adenosyl -L-methionine of the nuclear and the cytosolic enzymes were 2.5X10-sM and 3.8X10-sM respectively.
6) These enzymes were mostly distributed in the nucleus and the cytosof with comparable total activity and specific activity, but negligible activity was detected in mitochondrium and in microsome.
The above results suggested that the lymphocytes have two kinds of histone specific protein lysyl N-methyltransferases in the nuclear and in the cytosol fraction which may play different roles in cellular function.
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