肿瘤蛋白D52N-端乙酰化的纳升电喷雾串联质谱分析

N-terminal Acetylation Characterization of Tumor Protein D52 by Nano Electrospray Tandem Mass Mass Spectrometry

小鼠髓系白血病M1细胞经IL-6诱导分化后一系列蛋白质点的表达量发生了变化,其中A点表达量显著增加。MALDI-TOF-MS的肽质量指纹谱鉴定表明A点为肿瘤蛋白D52(tumor protein D52,TP D52)。为进一步确认该结果,对A点进行了ESI-MS/MS分析,测定了3个肽段的序列。Mascot数据库查询结果很肯定地表明该蛋白为TP D52,但只有两个肽段与之匹配。对未匹配肽段的序列分析表明它对应于TP D52N端1-10氨基酸MDRGEQGLLK,其中N端第1个氨基酸甲硫氨酸M发生了乙酰化。分析结果与M乙酰化的规律一致,即当第2个氨基酸是酸性氨基酸D或E时,M很容易发生乙酰化。本研究文首次报道了TP D52的N端乙酰化,其功能需要进一步研究。

M1 mouse myeloid leukemia cells were induced to-differentiate to huge cells after ld by rhIL-6. With two-dimensional gel analysis, spot A was found to be over expressed at 1 d after the induction and maintained their high levels till the fourth day. The spot was subjected to tryptic digestion and then analyzed by peptide mass fingerprint （PMF） of matrix assisted desorption ionization-time of flight-mass spectrometry （MALDI-TOF-MS） and nano-electrospray ionization tandem mass spectrometry （nano ESI-MS/MS）. Three peptides were sequenced and database search results of Mascot MS/MS ion search showed that two peptides matched to tumor protein D52 and the other one with m/z 1188.66 did not match to any protein. Sequence analysis of the MS/MS spectrum revealed that the peptide corresponded to the N-terminal peptide （1-10） of tumor protein D52 with the first methionin acetylated. The sequence of this N-terminal peptide is MDRGEQGLLK. The result matched to the previous knowledge of N^α-acetylation rules in eukaryotes, i.e. the N-terminal methionine is predominately acetylated when followed by either Asp or Glu. The exact role of this modification need be studied further.