Lysine separation from other amino acids

Most of the work in this field has been carried out in Butler s laboratory (Johns et al., 1960, 1961 Hnilica et al, 1962 Johns and Butler, 1962). As a result of their investigations, histone from thymus desoxyribonucleoprotein (DNP) was first separated by electrophoresis on starch into three fractions arginine (f3), lysine-rich (fj), and a fraction with a lower lysine content (f2). In fraction f3, alanine usually occupied the terminal position. Histones of the f2 group were separated by electrophoresis on starch into subfractions f2a and f2b, differing in their N-terminal groups. The lysine-rich fraction also was separated into la and fib> likewise differing in their N-terminal amino acids. Distinct differences between these fractions were also found for other amino acids. 

Three histone-specific acetyltransferases have been partially purified and characterized from rat thymus nuclei (225). The enzymes were extracted from rat thymus nuclei by sonication in the presence of 1M ammonium sulfate and separated into two active fractions (A and B) by DEAE-cellulose chromatography. Fraction B was further separated into two active fractions (Bi and B2) by gel filtration on Sephadex G-200. Each fraction was then purified further by chromatography on hydroxyapatite. The molecular weights, determined by Sephadex G-200 and by sucrose density gradient centrifugation, were 99,000, 110,000, and 92,000 for enzymes A, Bi, and B2, respectively. All three enzymes required acetyl CoA as acetate donor, and the activity of the enzymes was inhibited by p-chloromercuribenzoate. Acetyltransferase A preferentially acetylated histone I (FI) and also poly-L-lysine. Acetyltransferase Bi and B2 preferred histone H4 (other names IV, F2al) and did not acet-ylate poly-L-lysine and histone H3 (III, F3). In addition to c-N-acetyl-lysine, two other unidentified amino acid derivatives were obtained from a digest of histone H4 acetylated by the two B enzymes. 

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