Characterization of native and denatured ricin using MALDI-TOF/MS.
Ricin is a toxic protein present in the seeds of castor bean plant. It can be inactivated by heat; therefore characterization of denatured ricin is essential to differentiate it from native ricin and to avoid any ambiguity in its identification. In this study, potential of mass spectrometry using MALDI&mdash;TOF/MS has been exploited to investigate the effects of heat treatment on ricin and spiked food matrices. The molecular weights of ricin, ricin A (A1 and A2) and B chain were found to be 62.8 kDa, 31.2 kDa, 32.5 kDa and 32 kDa respectively. The mass spectrum revealed a polypeptide chain of 11.1 kDa for denatured ricin. The peptide mass fingerprinting showed 24 peptides, six were common both in native and denatured ricin. The differentiating peptide at position 294&mdash;318 (m/z 934.533) was observed only in denatured ricin. The three selected marker peptides m/z 1013.6, 1310.7, 1728.9 are chosen for identification of ricin inactivated by heat in spiked apple juice and milk samples by immunocapture analysis. There is always a probability of denatured non&mdash; toxic ricin being confused with native (toxic) ricin to create unnecessary panic. Keeping this probability in mind, our study will be of immense value in minimising such risk.
Defence Research & Development Establishment Division of Pharmacology & Toxicology Jhansi Road, Gwalior, India.
P
P
Sehgal
M K
MK
Rao
O
O
Kumar
R
R
Vijayaraghavan
D000595:Amino Acid Sequence; D015180:Electrophoresis, Gel, Two-Dimensional; D005506:Food Contamination / Q000032:analysis; D008969:Molecular Sequence Data; D011489:Protein Denaturation; D021122:Protein Subunits / Q000737:chemistry; D012276:Ricin / Q000737:chemistry* / Q000302:isolation & purification; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
D021122:Protein Subunits; D012276:Ricin