Calf thymus histone H2A. Purification and tryptic peptides

Area of Science:

• Biochemistry
• Molecular Biology
• Chromatography

Background:

• Histones are crucial for DNA packaging and gene regulation.
• Large-scale purification of specific histone variants like H2A is essential for detailed biochemical studies.
• Previous fractionation methods had limitations in purity and yield.

Purpose of the Study:

• To develop and compare three large-scale purification methods for calf thymus histone H2A.
• To assess the purity, yield, and simplicity of the developed methods.
• To prepare H2A for subsequent chemical and physical analyses, including peptide mapping.

Main Methods:

• Fractionation of calf thymus histone using CM-cellulose chromatography combined with Sephadex G-100 (Method I), Amberlite CG-50 and Bio-Gel P-10 (Method II), or a combination yielding purest H2A (Method III).
• Enzymatic digestion of purified H2A with trypsin.
• Fractionation of tryptic peptides using column chromatography.

Main Results:

• Method III provided the purest H2A and other histone species (H3, H4) with high yield and simplicity.
• Method I was effective for H2A purification when H3 contamination was minimal.
• Tryptic digestion and subsequent peptide analysis yielded 20 small and 2 large peptides, accounting for the complete H2A sequence.

Conclusions:

• Method III is a superior technique for the large-scale preparation of H2A and other histones.
• The developed purification and peptide mapping strategies enable comprehensive analysis of histone structure and function.
• This work provides a robust method for obtaining highly purified histone H2A for further research.