Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Biochem Biophys Res Commun. 2011 Aug 19;412(1):104-8. doi: 10.1016/j.bbrc.2011.07.052. Epub 2011 Jul 23.
Phenylbutanone raspberry ketone, accumulating in the mature fruits of raspberry (Rubus idaeus), imparts the characteristic aroma to the fruits. Here we describe the isolation and characterization of raspberry ketone/zingerone synthase 1 (RZS1), which catalyzed the NADPH-dependent reduction of 4-hydroxybenzalacetone and 3-methoxy-4-hydroxybenzalacetone to raspberry ketone and zingerone (the latter not found in raspberry), respectively. Its apparent K(m) values for 4-hydroxybenzalacetone and NADPH were 88 μM and 202 μM, respectively. RZS1 preferred 4-hydroxybenzalacetone to 3-methoxy-4-hydroxybenzalacetone as a substrate by a factor of 1.7, and showed a 6-fold preference for 4-hydroxybenzalacetone over p-coumaraldehyde, and no activity for coniferaldehyde. Expression analysis of the RZS1 gene throughout the plant revealed that its transcript level was highest in mature fruits. We conclude that RZS1 is responsible for hydrogenation of the α,β-unsaturated double bond of phenylbutenones, the final step of the raspberry ketone biosynthesis, in the raspberry fruits.
树莓酮/生姜酮合酶 1（RZS1）催化 NADPH 依赖型还原 4-羟基苯丁酮和 3-甲氧基-4-羟基苯丁酮，分别生成树莓酮和生姜酮（后者在树莓中不存在）。其对 4-羟基苯丁酮和 NADPH 的表观 K(m) 值分别为 88 μM 和 202 μM。RZS1 优先以 4-羟基苯丁酮作为底物，与 3-甲氧基-4-羟基苯丁酮的比例为 1.7:1，对 4-羟基苯丁酮的偏好是对 p-香豆醛的 6 倍，对 coniferaldehyde 没有活性。通过对 RZS1 基因在植物中的表达分析发现，其转录水平在成熟果实中最高。我们得出结论，RZS1 负责在树莓果实中催化苯丁烯酮的 α,β-不饱和双键的加氢反应，这是树莓酮生物合成的最后一步。
