Schneider Tom D, Roschitzki Bernd, Grossmann Jonas, Kraemer Thomas, Steuer Andrea E
Department of Forensic Pharmacology and Toxicology, Zurich Institute of Forensic Medicine, University of Zurich, 8057 Zurich, Switzerland.
Functional Genomics Centre Zurich, ETH Zurich/University of Zurich, 8057 Zurich, Switzerland.
Anal Chem. 2022 Aug 2;94(30):10695-10704. doi: 10.1021/acs.analchem.2c01009. Epub 2022 Jul 20.
Knowledge about when a bloodstain was deposited at a crime scene can be of critical value in forensic investigation. A donor of a genetically identified bloodstain could be linked to a suspected time frame and the crime scene itself. Determination of the time since deposition (TsD) has been extensively studied before but has yet to reach maturity. We therefore conducted a proof-of-principle study to study time- and storage-dependent changes of the proteomes of dried blood stains. A bottom-up proteomics approach was employed, and high-resolution liquid-chromatography-mass-spectrometry (HR-LC-MS) and data-independent acquisition (DIA) were used to analyze samples aged over a 2 month period and two different storage conditions. In multivariate analysis, samples showed distinct clustering according to their TsD in both principal component analysis (PCA) and in partial least square discriminant analysis (PLS DA). The storage condition alters sample aging and yields different separation-driving peptides in hierarchical clustering and in TsD marker peptide selection. Certain peptides and amino acid modifications were identified and further assessed for their applicability in assessing passed TsD. A prediction model based on data resampling (Jackknife) was applied, and prediction values for selected peptide ratios were created. Depending on storage conditions and actual sample age, mean prediction performances ranges in between 70 and 130% for the majority of peptides and time points. This places this study as a first in investigating LC-MS based bottom-up proteomics approaches for TsD determination.
了解血迹在犯罪现场的沉积时间，在法医调查中可能具有至关重要的价值。通过基因鉴定的血迹捐赠者可能与可疑的时间范围以及犯罪现场本身建立联系。此前，对血迹沉积时间（TsD）的测定已经进行了广泛研究，但尚未成熟。因此，我们开展了一项原理验证研究，以研究干血迹蛋白质组随时间和储存条件的变化。采用了自下而上的蛋白质组学方法，并使用高分辨率液相色谱-质谱联用仪（HR-LC-MS）和数据非依赖采集（DIA）来分析在两个月期间老化且处于两种不同储存条件下的样本。在多变量分析中，无论是在主成分分析（PCA）还是偏最小二乘判别分析（PLS DA）中，样本都根据其TsD显示出明显的聚类。储存条件会改变样本老化情况，并在层次聚类和TsD标记肽选择中产生不同的分离驱动肽。确定了某些肽和氨基酸修饰，并进一步评估了它们在评估过去的TsD方面的适用性。应用了基于数据重采样（留一法）的预测模型，并创建了所选肽比率的预测值。根据储存条件和实际样本年龄，大多数肽和时间点的平均预测性能范围在70%至130%之间。本研究首次对基于液相色谱-质谱联用仪的自下而上蛋白质组学方法用于TsD测定进行了研究。
