Quantification of HP1α-Histone Interactions

Recombinantly expressed and purified HP1α (MW = 22kDa) was purchased (lyophilized against PBS buffer) from Biomatik Corporation (www.biomatik.com) (Ontario, Canada). Unmodified and methylated histone H3 peptides (1 (link)–22 ) (MW =2354) were purchased in lyophilized form from Bachem Americas,Inc (Torrance, CA) (Bachem.com) and used as received. Chemicals including Alexa-488 C5-Maleimide, Dylight-594 NHS ester, Nucleic acid dimer sampler kit (YOYO-3 iodide, POPO-1 iodide), dsDNA (NoLimits 2.5kbp, 4kbp, 10kbp) as well as dialysis cassettes (Slide-A-Lyzer G2 3kda cutoff) were obtained from Thermo Fisher Scientific (Waltham, MA). Potassium chloride, Pluronics F127 was obtained from Sigma Aldrich (St. Louis, MO). HEPES ((4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid)) was obtained from Fisher Scientific (Pittsburg, PA). Peptides were reconstituted at 25 mg ml⁻¹ in nuclease-free ultra pure water as per the manufacturer’s instructions and stored as aliquots at −20°.HP1α was reconstituted (0.5 mg ml⁻¹) in nuclease-free ultra pure water as per the manufacturer’s instructions and stored (with 10% glycerol) as flash-frozen 200 ul aliquots in −80°C.