Effect of Conformation on the Photodegradation of Trp- And Cystine-Containing Cyclic Peptides: Octreotide and Somatostatin
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- 作者：Olivier Mozziconacci ; Christian Sch枚neich
- 刊名：Molecular Pharmaceutics
- 出版年：2014
- 出版时间：October 6, 2014
- 年：2014
- 卷：11
- 期：10
- 页码：3537-3546
- 全文大小：547K
- ISSN：1543-8392
文摘
The synthetic cyclic octapeptide octreotide is less stable under UV and fluorescent lights than its naturally occurring derivative somatostatin. Upon irradiation at 位 > 290 nm, and in the presence of oxygen, octreotide is quickly transformed into a photoproduct showing an increase of mass of 16 Da. The increase of 16 Da to the mass of octreotide is related to a complex transformation where (i) the side chain of d-Trp is transferred onto the side chain of the Lys residue and (ii) the former d-Trp residue is transformed into hydroxyglycine, which ultimately fragments. The complex sequence of phototransformation is orchestrated by the presence of d-Trp and the unusual orientation of its carbonyl group toward the disulfide bond. The phototransformation of octreotide is illustrated by product A.