Ricin molecular weight

Toxins (typically high molecular weight proteins), such as botulinum toxin, ricin, or Staphyloccocal enterotoxin (SEB) or T-2 toxin (which actually is a small molecule). 

Gelonin and PAPs are much more convenient to work with than ricin and the other two-subunit toxins. Most importantly, they are relatively nontoxic to cells unless conjugated with something that can facilitate cell binding and internalization (Stirpe et al., 1980 Irvin, 1983). The pi of these toxins is in the basic range, and they each have a molecular weight of about 30,000 (Barbieri and Stirpe, 1982). These single-subunit... 

Ishiguro, M., Takahashi, T., Hayashi, K., Funatsu, M. (1964h). Biochemical studies on ricin. II. Molecular weight and... 

Biological toxins typically are of lesser molecular weight and size, and are thus more soluble and more easily penetrate the skin than chemical weapon agents. Biological toxins can be categorized based upon their mode of action, such as neurotoxins (disrupt nerve impulses) and cytotoxins (disrupt cell respiration and metabolism). Known biological toxins that are warfare or terror agents include aflatoxin, botuli-num toxins, ricin, and T2 mycotoxin. 

A group of plant lectins, such as abrin, ricin, and mod-eccin, are highly toxic to eukaryotic cells. Their mode of action consists of inhibition of protein synthesis by enzymatically inactivating the EF-2 binding region of the 60S ribosomal subunit, whereas the diphtheria toxin inactivates the EF-2 protein itself. Ricin is isolated from castor beans and has a molecular weight of 66,000. Like most plant and bacterial toxic proteins, ricin contains two... 

Like ricin, abrin is a type 2 ribosome inactivating protein with A and B chains linked by a disulphide bond. The abrin A chain comprises 251 amino acid residues compared to 267 in the ricin A chain, both having three folding structural domains and a molecular weight of approximately 30 kDa. The abrin B chain has a molecular weight of 35 kDa with 60% of its amino acid residues identical to those of ricin s B chain. Both B chains have two saccharide binding sites which are highly conserved between the two toxins. 

SPR is a representative physical phenomenon that is widely utilized for label-free characterization of molecules on thin metal films. The basic principle and operation of SPR has been described in more detail in several review articles [77, 78]. The reports on SPR-based immune sensors have steeply increased for detection of analytes with low molecular weights in recent years. SPR detection in microfluidic systems can provide various advantages. Immunoreactions are completed within a short time due to small sample volumes down to the nanolitre scale. Kim et al. developed a simple and versatile miniaturized SPR immunosensor enabling parallel analyses of multiple analytes [79]. Their SPR sensor was claimed to exhibit good stability and reusability for 40 cycles and more than 35 days. Feltis et al. demonstrated a low-cost handheld SPR-based immunosensor for the toxin Ricin [80]. Springer et al. reported a dispersion-free microfluidic system with a four-channel SPR sensor platform, which considerably improved the response time and sensitivity [81]. The sensor was able to detect short sequences of nucleic acids down to a femtomole level for 4 min. Waswa et al. demonstrated the immunological detection of E. coli 0157 H7 in milk, apple juice, and meat juice extracted from... 

Figure 5.1-3. SDS-CGE electropherograms of molecular weight standard marker (14-200kDa) (A) and ricin toxin glycoprotein under nonreducing conditions (B). The right insert is an enlargement of ricin peaks in SDS-CGE, presenting the partially separated two peaks (i s = 0.74) compared with only a single band shown in the SDS-PAGE gel. (Reprinted from Ref. 29, with permission.)...

AC is included in the recommended treatment of ricin, saxitoxin, T2 mycotoxins and botulinum toxin poisoning although its efficacy remains to be proven [65,71]. It is interesting that rather large objects such as bacteria (0.1-10 pm) can be retained by AC at all these results suggest that the nature of AC surface - bacteria interaction cannot be attributed to physical adsorption only for smaller objects such as vimses (10-100 ran) and molecules of biotoxins which have molecular weight up to 1000 kDa contribution of adsorption in mesopores may be important. 

Enzyme-linked immunosorbent assays (for blood or other body fluids)50 or immunohistochemical techniques (for direct analysis of tissues) may be useful in confirming ricin intoxication. However, because ricin is bound very quickly regardless of route of challenge, and metabolized before excretion, identification in body fluids or tissues is difficult. In rats exposed to ricin labeled with iodine 125 by intravenous injection, the radioactive label was found in liver (46%), muscle (13%), and spleen (9%) 30 minutes after intravenous injection.51 Ricin was quickly cleared from the animals, with only 11% remaining after 24 hours 70% was excreted in the urine as low-molecular-weight metabolites. Attempts at identification of the toxin may also include introduction of biological autopsy materials into mice or cultured cells and neutralization through the use of specific antibodies. 

T. from plants (phytotoxins) include both high- and low-molecular weight substances. Examples of the former are the lectins distributed in legumes (abrin, con-canavalin A, crotin, phasin, ricin). The low-molecular weight plant T. are more numerous and of greater diversity, including the cardiac glycosides, saponins. 

A recent report described MALDI-TOF MS characterization of ricin, an extremely potent poison from the seeds of the castor bean plant. Ricin has been mentioned in terrorism literature and was reportedly used in a high profile international spy homicide case. In the MS application, samples were first purified by LC fractionation or molecular weight cutoff filtration. Confirmation was carried out by comparing the MALDI-TOF MS spectrum of the tryptic digest against a standard and GC-MS identification of an alkaloid marker, ricinine. 

The brilliant red black seeds oiAbrus precatorius (precatory bean) contain abrin, an extremely toxic protein (Ghosal and Dutta, 1971). Seeds of this plant are commonly used in the tropics to make necklaces and other jewelry. One seed, if thoroughly masticated, is sufficient to cause death in a child (Kingsbury, 1964). The lectins of this plant primarily bind galactose and are similar in properties to those of ricin (see below). The lectin has a molecular weight of 65,000 and is composed of dissimilar peptides. 

Dual analyses of ricin proteins are performed with MALDI-TOF-MS and LC-MS methods. MALDI-TOF-MS analysis is only able to determine an approximate molecular weight (MW) due to posttranslational modifications that cause ricin to be heavily glycosylated. Thus, LC-MS/MS is employed in concert with MALDI-TOF-MS analyses to identify peptides for accurate protein sequencing from a protein digest [80, 82-83]. Typical detection limits for the MALDI-TOF-MS analysis are between 50 ng/mL and 4 pg/mL. The proteomic... 

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