{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,16]],"date-time":"2026-10-16T02:46:51Z","timestamp":1792118811051,"version":"4.4.0"},"reference-count":16,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2023,11,30]],"date-time":"2023-11-30T00:00:00Z","timestamp":1701302400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ravgen, Inc. (Columbia, MD, USA)"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Streck tubes are commonly used to collect blood samples to preserve cell-free circulating DNA. They contain imidazolidinyl urea as a formaldehyde-releasing agent to stabilize cells. We investigated whether the released formaldehyde leads to crosslinking of intracellular proteins. Therefore, we employed a shotgun proteomics experiment on human peripheral blood mononuclear cells (PBMCs) that were isolated from blood collected in Streck tubes, EDTA tubes, EDTA tubes containing formaldehyde, or EDTA tubes containing allantoin. The identified crosslinks were validated in parallel reaction monitoring LC\/MS experiments. In total, we identified and validated 45 formaldehyde crosslinks in PBMCs from Streck tubes, which were also found in PBMCs from formaldehyde-treated blood, but not in EDTA- or allantoin-treated samples. Most were derived from cytoskeletal proteins and histones, indicating the ability of Streck tubes to fix cells. In addition, we confirm a previous observation that formaldehyde crosslinking of proteins induces a +24 Da mass shift more frequently than a +12 Da shift. The crosslinking capacity of Streck tubes needs to be considered when selecting blood-collection tubes for mass-spectrometry-based proteomics or metabolomic experiments.<\/jats:p>","DOI":"10.3390\/molecules28237880","type":"journal-article","created":{"date-parts":[[2023,12,1]],"date-time":"2023-12-01T04:12:56Z","timestamp":1701403976000},"page":"7880","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Mass Spectrometric Detection of Formaldehyde-Crosslinked PBMC Proteins in Cell-Free DNA Blood Collection Tubes"],"prefix":"10.3390","volume":"28","author":[{"given":"Daniel","family":"R\u00f6th","sequence":"first","affiliation":[{"name":"Department of Immunology and Theranostics, Arthur Riggs Diabetes and Metabolism Research Institute, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6865-3153","authenticated-orcid":false,"given":"Jessica","family":"Molina-Franky","sequence":"additional","affiliation":[{"name":"Department of Immunology and Theranostics, Arthur Riggs Diabetes and Metabolism Research Institute, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA"},{"name":"Molecular Biology and Immunology Department, Fundaci\u00f3n Instituto de Inmunolog\u00eda de Colombia (FIDIC), Bogot\u00e1 112111, Colombia"},{"name":"Biotechnology Institute Department, Faculty of Sciences, Universidad Nacional de Colombia, Bogot\u00e1 111321, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0522-384X","authenticated-orcid":false,"given":"John C.","family":"Williams","sequence":"additional","affiliation":[{"name":"Department of Cancer Biology and Molecular Medicine, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9506-671X","authenticated-orcid":false,"given":"Markus","family":"Kalkum","sequence":"additional","affiliation":[{"name":"Department of Immunology and Theranostics, Arthur Riggs Diabetes and Metabolism Research Institute, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,11,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e12315","DOI":"10.1002\/jev2.12315","article-title":"Benchmarking blood collection tubes and processing intervals for extracellular vesicle performance metrics","volume":"12","author":"Dhondt","year":"2023","journal-title":"J. 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