伪枝藻素(英語:Scytonemin)是一种生物色素,由许多藍细菌合成,包括Calothrix sp.[2]Lyngbya aestuarii[3]等,最早在1849被人发现,但直到1993年才解析了其结构[4]。据信,伪枝藻素对细菌起到了防曬油的作用,在325-425 nm的有很大的吸收峰,并在250 nm的紫外波段有个独立的吸收峰[4],在暴露在紫外线的情况下才启动它的生物合成[5]

伪枝藻素
IUPAC名
(3E,3'E)-3,3'-bis(4-hydroxybenzylidene)-[1,1'-bi(cyclopenta[b]indole)]-2,2'(3H,3'H)-dione
别名 Scytonemin
识别
CAS号 152075-98-4  checkY
性质
化学式 C36H20N2O4
摩尔质量 544.6 g/mol g·mol⁻¹
外观 brown solid[1]
溶解性 25mg/ml DMSO
λmax 325-425nm nm
若非注明,所有数据均出自标准状态(25 ℃,100 kPa)下。

生物合成

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Lyngbya aestuarii 体内的伪枝藻素生物合成途径最近由 Balskus、Case和Walsh 发现。它起始于L-色氨酸3-吲哚丙酮酸的转化,之后再与对羟基苯丙酮酸结合。产物的β-酮酸基 再发生环化形成带羰基的三环化合物,之后再氧化二聚化形成伪枝藻素,三个反应步骤依次由ScyB、ScyA、ScyC催化,如下图所示[3]

 
Scytonemin biosynthesis in Lyngbya aestuarii.[3]

参考文献

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  1. ^ Scytonemin CAS (152075-98-4). Santa Cruz Biotechnology, Inc. [2011-05-30]. (原始内容存档于2011-10-02). 
  2. ^ Dillon, Jesse G.; Castenholz, Richard W. The synthesis of the UV-screening pigment, scytonemin, and photosynthetic performance in isolates from closely related natural populations of cyanobacteria (Calothrix sp.). Environmental Microbiology. 2003, 5 (6): 484–91. PMID 12755715. doi:10.1046/j.1462-2920.2003.00436.x. 
  3. ^ 3.0 3.1 3.2 Balskus, Emily P.; Case, Rebecca J.; Walsh, Christopher T. The biosynthesis of cyanobacterial sunscreen scytonemin in intertidal microbial mat communities. FEMS Microbiology Ecology. 2011: 1–11. doi:10.1111/j.1574-6941.2011.01113.x. 
  4. ^ 4.0 4.1 Proteau, P. J.; Gerwick, W. H.; Garcia-Pichel, F.; Castenholz, R. The structure of scytonemin, an ultraviolet sunscreen pigment from the sheaths of cyanobacteria. Experientia. 1993, 49 (9): 825–9. PMID 8405307. doi:10.1007/BF01923559. 
  5. ^ M. Bandaranayake, Wickramasinghe. Mycosporines: are they nature’s sunscreens?. Natural Product Reports. 1998, 15 (2): 159–72. PMID 9586224. doi:10.1039/A815159Y. 

外部链接

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  • Balskus, Emily P.; Case, Rebecca J.; Walsh, Christopher T. The biosynthesis of cyanobacterial sunscreen scytonemin in intertidal microbial mat communities. FEMS Microbiology Ecology. 2011: no–no. doi:10.1111/j.1574-6941.2011.01113.x.