Detection of ricin activity and structure by using novel galactose-terminated magnetic bead extraction coupled with mass spectrometric detection

• Published in: Analytical biochemistry Vol. 631; p. 114364
• Main Authors: Hoyt, Kaitlin, Barr, John R., Kalb, Suzanne R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.10.2021
• Subjects: Animals; Antibodies - chemistry; Biotyper; Food Contamination - analysis; Galactose - chemistry; Galactose affinity; Lactase - chemistry; Limit of Detection; Magnetic Phenomena; MALDI; Mass spectrometry; Microspheres; Milk - chemistry; Plant Extracts - analysis; Powders - analysis; Powders - chemistry; Reproducibility of Results; Ricin; Ricin - analysis; Ricin - chemistry; Ricin - metabolism; Ricinus - chemistry; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - instrumentation; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; Trypsin - chemistry; Biotyper; Galactose affinity; Ricin; Mass spectrometry; MALDI
• DOI: 10.1016/j.ab.2021.114364
• ISSN: 0003-2697

Ricin is a toxic protein derived from the castor bean plant (Ricinus communis) and has potential for bioterrorism or criminal use. Therefore, sensitive and rapid analytical methods are needed for its confirmatory detection in environmental samples. Our laboratory previously reported on the development of a confirmatory method to detect ricin involving antibody capture of ricin followed by mass spectrometric detection of ricin's enzymatic activity and of tryptic fragments unique to ricin. Here, we describe a novel ricin capture method of magnetic beads coated with 4-aminophenyl-1-thiol-β-galactopyranoside, using ricin's lectin characteristics. The assay has been adapted for use on a simple, benchtop MALDI-TOF MS mass spectrometer common in clinical microbiology laboratories. Validation of the novel assay includes establishment of a limit of detection, and an examination of assay selectivity. The limit of detection of the enzymatic activity method is 8 ng/mL and 500 ng/mL for the confirmatory tryptic fragment assay. The assay is highly selective with no cross-reactivity from near neighbors and highly specific with a panel of 19 cultivars all testing positive. Additionally, there were no interferences found during testing of a panel of white powders. This allows for a confirmatory detection method for ricin in laboratories lacking expensive, sophisticated mass spectrometers. [Display omitted] •Development of novel galactose-terminated magnetic beads to extract ricin.•Extracted ricin used for activity and structural assays for confirmatory detection.•Confirmatory detection of biologically-active ricin on benchtop mass spectrometer.