| 摘要 |
Ribosome inactivator proteins known as nigrin I1 and nigrin I2 from the plant Sambucus nigra L., process for obtaining them and preparation Type 2 nigrin I1 and nigrin I2 (comprising two polypeptide chains) have relative molecular masses of 59,500 daltons in the absence of a reducing agent. They have two B chains and one A chain joined by disulphide bridges which in the presence of a reducing agent have an Mr of 33,500 and 34,000 daltons for the B chains and 26,000 for the A chain. They have the following amino acid sequences at their amine terminal ends: Nigrin I1: Chain A: Ile-Asp-Tyr-Pro-Ser-Val-Ser-Phe-Asn-Leu-Asp-Gly- Ala-Lys-Ser-Ala-Thr-Tyr-Arg-Asp. Chain B: Asp-Gly-Glu-Thr-Xaa-Thr-Leu-Arg-Thr-Ser-Phe-Thr- Arg-Asn-Ile-Val-Gly-Xaa-Asp-Gly. Nigrin I2: Chain A: Ile-Asp-Tyr-Pro-Ser-Val-Ser-Phe-Asn-Leu-Asp-Gly- Ala-Lys-Ser-Ala-Thr-Tyr-Arg-Asp-Phe-Leu-Ser-Asn. Chain B: Asp-Gly-Glu-Thr-Xaa-Thr-Leu-Arg-Thr-Ser-Phe-Thr- Arg-Asn-Ile-Val-Gly-Xaa-Asp-Gly. The general process for obtaining RIPs from Sambucus nigra L. according to this invention comprises isolating them from broths of Sambucus nigra L., including a first extraction operation including an aqueous solution based on sodium chloride and monosodium phosphate to obtain an extract which is capable of inhibiting protein synthesis, followed by the purification of this using affinity, molecular exclusion and ion exchange chromatography techniques. Nigrin I1 and nigrin I2 are used as ribonucleic acid inactivators and inhibitors of protein biosynthesis.
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