Agerbirk Niels, Warwick Suzanne I, Hansen Paul R, Olsen Carl E
Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark.
Phytochemistry. 2008 Dec;69(17):2937-49. doi: 10.1016/j.phytochem.2008.08.014. Epub 2008 Nov 6.
Levels of sinalbin (4-hydroxybenzylglucosinolate) and 28 other glucosinolates were determined in leaves and roots of 20 species that were either phylogenetically close to Sinapis alba, Sinapis arvensis, or Sinapis pubescens (tribe Brassiceae, Brassicaceae), or were expected to contain arylalkyl nitrilase activity. Comparison with a molecular phylogenetic tree based on ITS DNA sequences identified two separate occurrences of sinalbin. The first in a group of species related to S. alba (including members of the genera Coincya and Kremeriella); and the second in S. arvensis, nested among sinalbin deficient species. Significant 4-hydroxyphenylacetonitrile degrading enzyme activity was found in both S. alba and S. arvensis, but in S. alba the major product was the corresponding carboxylic acid, while in S. arvensis the major product was the amide. Both investigated enzyme activities, nitrilase and nitrile hydratase, were specific, accepting only certain arylacetonitriles such as 4-hydroxy and 4-methoxyphenylacetonitrile. Only the S. alba enzyme required an oxygen in para position of the substrate, as found in sinalbin. Indole-3-acetonitrile, arylcyanides, and arylpropionitriles were poor substrates. The nitrilase activity of S. alba was quantitatively comparable to that reported in the monocot Sorghum bicolor (believed to be involved in cyanogenic glycoside metabolism). Glucosinolates derived from methionine were found in all Sinapis clades. Glucosinolate patterns suggested a complex evolution of glucosinolates in the investigated species, with several apparent examples of abrupt changes in glucosinolate profiles including chain length variation and appearance of glucosinolates derived from branched-chain amino acids. NMR data for desulfated homosinalbin, 9-methylsulphonylnonylglucosinolate, 3-methylpentylglucosinolate and related glucosinolates are reported, and a facultative connection between sinalbin and specific nitrilases is suggested.
测定了20种植物叶片和根中芥子碱（4-羟基苄基芥子油苷）及其他28种芥子油苷的含量，这些植物要么在系统发育上与白芥、野芥或柔毛芥（十字花科芸苔族）相近，要么预期含有芳基烷基腈水解酶活性。与基于ITS DNA序列构建的分子系统发育树比较后发现，芥子碱有两次独立出现的情况。第一次出现在与白芥相关的一组物种中（包括Coincya属和Kremeriella属的成员）；第二次出现在野芥中，夹在缺乏芥子碱的物种之间。在白芥和野芥中均发现了显著的4-羟基苯乙腈降解酶活性，但在白芥中主要产物是相应的羧酸，而在野芥中主要产物是酰胺。所研究的腈水解酶和腈水合酶这两种酶活性都具有特异性，仅接受某些芳基乙腈，如4-羟基和4-甲氧基苯乙腈。只有白芥的酶需要底物对位有一个氧原子，这与芥子碱中的情况相同。吲哚-3-乙腈、芳基氰化物和芳基丙腈是较差的底物。白芥的腈水解酶活性在数量上与单子叶植物高粱中报道的活性相当（据信与氰苷代谢有关）。在所有白芥分支中都发现了源自蛋氨酸的芥子油苷。芥子油苷模式表明所研究物种中芥子油苷的进化很复杂，有几个明显的例子显示芥子油苷谱突然变化，包括链长变化和源自支链氨基酸的芥子油苷的出现。报道了脱硫高芥子碱、9-甲基磺酰基壬基芥子油苷、3-甲基戊基芥子油苷及相关芥子油苷的核磁共振数据，并提出了芥子碱与特定腈水解酶之间的一种兼性联系。
