Acetylation and methylation of flavins and the effects on isoalloxazinc ring protonation
Acetylation and methylation of flavins and the effects on isoalloxazinc ring protonation
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黄素的乙酰化和甲基化及其对异恶嗪环质子化的影响
DOI：
10.1002/jhet.5570110621
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发表时间：
1974
影响因子：
2.4
通讯作者：
D. B. Mccormick
中科院分区：
文献类型：
--
作者：
D. B. Mccormick
7，8-二甲基异氧嘧啶的N10-(多)羟基侧链的乙酰化反应是以高氯酸为催化剂，以过量的醋酸酐为黄素或在吡啶中为辅酶D-核黄素-5‘-磷酸(FMN)完成的。虽然具有不同羟基烷基链的黄素的伯醇和仲醇功能发生了完全的乙酰化，但通过与FMN反应的DEAE-纤维素层析，然后中和，纯化的主要产物是2‘，3’-双乙酰衍生物。二乙酰FmN和其他乙酰化黄素表现出异四氮杂氮化合物的常见吸收光谱，λ最大值分别为390、264和222 nm，仅当其羟基或特别是脱氧对应的酸化程度超过所需时才显示。用甲基碘化物和二甲基甲酰胺中的氧化银处理来甲基化的黄素也有类似的效果，但不是很明显。发生在最碱性氮1上的异四氮唑环的质子化最有效地受到近端2‘-羟基的乙酰化或甲基化的影响。
The acetylation of N10-(poly)hydroxy side chains of 7,8-dimethylisoalloxazines has been accomplished in conventional ways using perchloric acid as catalyst with excess acetic anhydride in acetic acid for flavins or in pyridine for the coenzyme, D-riboflavin-5′-phosphate (FMN). Although complete acetylation of the primary and secondary alcoholic functions of flavins with various hydroxyalkyl chains occurs, the primary product purified by DEAE-cellulose chromatotraphy of the reaction with FMN, followed by neutralization, is the 2′,3′-diacetyl derivative. Diacetyl FMN and other acetylated flavins exhibit the usual absorption spectra of prolonated isoalloxazinium compounds, with λ max values of 390, 264, and 222 nm, only upon greater acidification than necessary for their hydroxy or especially deoxy counterparts. A similar though less marked effect is found with flavins methylated by treatment with methyl iodide and silver oxide in dimethylformamide. Protonation of the isoalloxazine ring, which occurs on the most basic nitrogen 1, is most effectively impaired by acetylation or methylation of the proximal 2′-hydroxyl group.