LATI 3503 Lecture Notes - Lecture 1: Protein Disulfide-Isomerase, Ricin, Ubiquitin Ligase
20 Oct 2017
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Document Summary
Ricin (/ ra s n/ rye-sin) is a highly toxic, naturally occurring lectin (a carbohydrate- binding protein) produced in the seeds of the castor oil plant, ricinus communis. A dose of purified ricin powder the size of a few grains of table salt can kill an adult human. [1] the median lethal dose (ld50) of ricin is around 22 micrograms per kilogram of body weight if the exposure is from injection or inhalation (1. 78 milligrams for an average adult). [2] oral exposure to ricin is far less toxic as some of the poison is inactivated in the stomach. An estimated lethal oral dose in humans is approximately 1 milligram per kilogram. Ricin is classified as a type 2 ribosome-inactivating protein (rip). Rips are composed of a single protein chain that possesses catalytic activity, type 2. Rips, also known as holotoxins, are composed of two different protein chains that form a heterodimeric complex.
