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目的研究大头金蝇Chrysomyia megacephala蛹壳风化不同时间的蛋白质降解,探讨其在法医学死亡时间推断上的意义。方法收集人工饲养的C.megacephala蛹壳,放置于树林内5、10天后收回,进行红外光谱采集及预处理,读取蛋白质酰胺吸收峰,并对每组平均光谱进行曲线拟合。应用SPSS 19.0软件进行统计学分析。结果与对照组相比,风化5天组,蛋白质酰胺Ⅰ的峰位蓝移,酰胺Ⅱ的峰位变化无统计学意义,且酰胺Ⅰ及Ⅱ的峰强度变化均无统计学意义。蛋白质的二级结构,α-helix略减少且β-sheet略增加,而β-turn无变化;风化10天组,蛋白质酰胺Ⅰ及Ⅱ的峰位均蓝移,酰胺Ⅰ吸收峰出现明显肩峰,且酰胺Ⅰ及Ⅱ的峰强度均明显下降。蛋白质二级结构,α-helix及β-sheet的变化趋势与5天组一致,而β-turn显著增加。结论红外光谱显示C.megacephala蛹壳风化10天内,蛋白质酰胺Ⅰ及Ⅱ的吸收峰变化开始呈现出一定的特征性,可辅助较长时间的死亡时间推断。
Objective To study the proteolysis of pupae of Chrysomyia megacephala at different times of weathering, and to explore its significance in the time of forensic death. Methods The pupal shell of C.megacephala was collected and placed in the woods for 5 days and 10 days before recovering. The infrared spectra were collected and pretreated to read the protein amide absorption peak. The average spectra of each group were curve fitted. SPSS 19.0 software was used for statistical analysis. Results Compared with the control group, the peak position of protein amide Ⅰ was blue-shifted and the peak position of amide Ⅱ was not statistically significant in the 5-day weathering group. There was no significant difference in peak intensities between amide Ⅰ and Ⅱ. Protein secondary structure, α-helix slightly reduced and β-sheet slightly increased, and β-turn no change; weathered 10-day group, protein amide Ⅰ and Ⅱ peak position are blue shift, amide Ⅰ absorption peak obvious shoulder , And the peak intensities of amides Ⅰ and Ⅱ decreased obviously. The changes of protein secondary structure, α-helix and β-sheet were consistent with those of the 5-day group, while β-turn was significantly increased. Conclusion The IR spectra of C.megacephala pupae shell showed that the changes of the absorption peaks of amide Ⅰ and Ⅱ began to show certain characteristics within 10 days after weathering, which could help to infer the longer death time.