The alpha-amino groups of histones H4 and H2A can be acetylated by histone N-terminal acetyltransferase 11(Nat11), which plays an important role in epigenetic regulation. The cDNA of human Nat11 was amplified and cloned into pSUMO vector. The resultant construct was transformed into E.coli strain BL21(DE3)for recombinant protein expression. Homogenous Nat11 was highly purified through a series of purification procedures including nickel column affinity chromatography. Using isothermal titration calorimetry(ITC), we measured micromolar binding constants between Nat11 and histone H4 peptides. MALDI-TOF mass spectrometry analysis revealed that purified Nat11 was pre-bound with acetyl coenzyme A or coenzyme A that was co-purified from E.coli. After ITC titration using unmodified peptide as ligand, N-acetylated product was detected by mass spectrometry, suggesting that the purified Nat11 is active. We performed crystallization screening and successfully obtained single crystal of a truncate form of Nat11 and substrate-enzyme recombinant protein after optimization.%α-氨基乙酰基转移酶11（Nat11）催化组蛋白H4和H2A氨基端乙酰化修饰，发挥着重要的表观遗传调控功能。将人Nat11基因构建到原核表达载体pSUMO中，转化入大肠杆菌BL21（DE3）进行重组表达。通过镍柱亲和层析等一系列体外纯化步骤，获得高纯度Nat11。利用等温滴定量热法（ITC），测得Nat11与底物多肽微摩尔量级结合常数。利用质谱技术，发现纯化后的Nat11结合有大肠杆菌内源产生的乙酰辅酶A或辅酶A，在ITC滴定过程中可以产生对多肽底物的乙酰化修饰，表明纯化获得的Nat11在溶液中具有酶活力。随后，对Nat11进行晶体生长研究，通过初筛优化获得蛋白截短体及底物-酶融合蛋白单晶。
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