Garrido José L, Otero Jorge, Maestro Miguel A, Zapata Manuel
Instituto de Investigacións Mariñas, Consejo Superior de Investigaciones Científicas Av. Eduardo Cabello, 6, E-36208-Vigo, SpainServicios Xerais de Apoio á Investigación, Universidade da Coruña, E-15071 A Coruña, SpainCentro de Investigacións Mariñas, Consellería de Pesca, Xunta de Galicia. Apdo. 13, E-36620 Vilanova de Arousa, Spain.
J Phycol. 2000 Jun;36(3):497-505. doi: 10.1046/j.1529-8817.2000.99135.x. Epub 2001 Dec 25.
The main nonpolar chlorophyll c -like pigment was extracted from Emiliania huxleyi (Lohm.) Hay et Mohler (strain CCMP 370) cultures and isolated by preparative column chromatography and HPLC. The pigment, whose visible spectrum closely resembled that of chlorophyll c , was studied by low-resolution fast atom bombardment mass spectrometry, showing a very high mass molecular ion (m/z 1313). The fragment ions, either in the direct spectrum or obtained by tandem mass spectrometry with collision-induced dissociation of the molecular ion, were compatible with the consecutive losses of two fatty acids (14:0 and 18:4), glycerol, and a hexose, leaving a chlorophyll c backbone, suggesting the molecule consists of a chlorophyll c residue linked, via an ester bond, to the sugar moiety of a monohexosyldiacylglycerol. The identities of the two fatty acid residues (14:0 and 18:4n-3) were subsequently corroborated by gas chromatography of the corresponding methyl esters. Chemical hydrolysis-derivatization-gas chromatography-mass spectrometry demonstrated the occurrence of glycerol and that galactose is the constituent sugar. The porphyrin obtained on acid hydrolysis showed chromatographic and visible spectral properties identical to pheoporphyrin c . This evidence led us to propose a tentative structure whose molecular formula, C H O N Mg, was supported by the values of exact mass measurements by high-resolution fast atom bombardment mass spectrometry. This novel structure represents the highest molecular weight natural chlorophyll described to date.
主要的非极性类叶绿素c色素是从赫氏颗石藻（Emiliania huxleyi (Lohm.) Hay et Mohler，CCMP 370菌株）培养物中提取的，并通过制备柱色谱法和高效液相色谱法进行分离。该色素的可见光谱与叶绿素c非常相似，通过低分辨率快原子轰击质谱法对其进行研究，结果显示其具有非常高的质量分子离子（m/z 1313）。无论是直接质谱图中的碎片离子，还是通过分子离子碰撞诱导解离的串联质谱法获得的碎片离子，都与两个脂肪酸（14:0和18:4）、甘油和一个己糖的连续损失相匹配，留下了叶绿素c骨架，这表明该分子由一个通过酯键与单己糖二酰甘油的糖部分相连的叶绿素c残基组成。随后，通过相应甲酯的气相色谱法证实了两个脂肪酸残基（14:0和18:4n-3）的身份。化学水解-衍生化-气相色谱-质谱法证明了甘油的存在，且半乳糖是构成糖。酸水解后得到的卟啉显示出与脱镁叶绿素c相同的色谱和可见光谱特性。这些证据使我们提出了一个暂定结构，其分子式为C H O N Mg，高分辨率快原子轰击质谱法的精确质量测量值支持了该分子式。这种新结构代表了迄今为止所描述的分子量最高的天然叶绿素。
