Trichobitacin - A new ribosome-inactivating protein .1. The isolation, physicochemical and biological properties of trichobitacin

From the press-residue of the fresh root tuber of Trichosanthes kirilowii Maxim (Cucurbitaceae), a new ribosome-inactivating protein (RIP), trichobitacin, was isolated. It has the activity of RNA N-glycosidase and can inhibit the growth of human placental trophoblastic cells. Its molecular weight is 27,228 Da (ES-MS) and pI 9.6. It is a single chain basic RIP. Its amino acid composition was determined. It is a new RIP. It consists of 0.7 similar to 0.9% galactose and may be a glycoprotein. Its N- and C-terminal amino acid is Asp and Ala, respectively. Its N-terminal preliminary amino acid sequence has been determined.