Résumé
Objective To observe the protein degredation of empty puparium cases ofC. megacephala after weathering and to explore its practical significance on postmortem interval estimation in forensic science. MethodsThe standardized feeding was used inC. megacephala, and the empty puparium cases were collected and put into the forest. They were taken back 5 days, and 10 days later, respectively. The spectra were collected and preprocessed, and then the absorption peaks of amides were read, and curve fitting was performed in the average spectra of each group. The statistical analysis was performed by SPSS 19.0.Results Compared to control group, ifve days post weathering, the position of amideⅠabsorption peak showed blue shift, but the amideⅡabsorption peak showed no shift, moreover, none of the amide absorption peaks showed changes inpeak intensity. For the secondary structures, α-helix decreased and β-sheet increased slightly, however, β-turn did not change; Ten days post weathering, the positions of both amideⅠandⅡabsorption peaks showed blue shift, and an obviousshoulder peak appeared in amide I absorption peak. Meanwhile, both of amideⅠandⅡabsorption peaks showed decreased in peak intensity. Moreover, for the secondary structures, α-helix and β-sheet showed the same tendency as in the 5th day group, except for the β-turn increased dramaticlly.Conclusion The spectra of the empty puparium cases of C. megacephala showed that the absorption peaks of amideⅠandⅡpresented certain characteristic features within ten days post weathering, and estimate relative long-time postmortem interval.