Chemoenzymatic routes to rose oxide

玫瑰的香味是香水行业中最受追捧的香味之一，也是家用和个人产品中最受追捧的香味之一。淡香水含有较轻、挥发性较强的玫瑰精油成分，如香茅醇和香叶醇。香水更持久，因为它们含有较少的挥发性成分，如玫瑰酮、大马士革酮、离子酮等。玫瑰精油的另一种成分是小分子玫瑰氧化物。虽然它在玫瑰精油中的含量很低，但它的气味阈值为十亿分之一，除了大马士革酮外，它对玫瑰气味的贡献比其他所有化合物都要大。玫瑰氧化物被描述为具有花香和绿色的气味，它非常重要，以至于当这种化合物首次从保加利亚玫瑰油中分离出来时，印制了印有其分子结构的邮票。玫瑰氧化物是一种高价值的精细化学品，因为需要3吨玫瑰花才能产生1公斤玫瑰精油，其中玫瑰氧化物含量<0.1%。从自然来源分离的材料价格昂贵（每公斤7000美元）。商业上，玫瑰氧化物是由香茅醛化学途径生产的；一种方法使用溴，而其他方法需要生产和使用污染的试剂。本项目旨在开发一种以香茅醇为原料制备玫瑰氧化物的生物工艺，其关键步骤是氧化香茅醇中的特定碳氢键。这些键是化学惰性的，这导致更复杂的路线或更污染的过程，以使用香茅醛作为原料。我们已经开发出能够在环境温度下在水中执行这一关键步骤的酶变体。该项目的行业合作伙伴正在通过可持续和无污染的生物技术过程将其用于商业规模的玫瑰氧化物生产。该项目的目的是开发更多的活性酶和基于香茅醛的替代原料，以使玫瑰氧化物工艺更加高效和多产。先进的计算方法也将应用于帮助指导酶的设计和工艺开发。

The scent of the rose is one of the most sought after in the fragrance industry and for more general domestic as well as personal products. Eau de toilette contains the lighter, more volatile rose essential oil components such as citronellol and geraniol. Perfumes are longer lasting as they contain less volatile components such as the rose ketones damascone, damascenone, ionones and the like. Another component of rose essential oil is the small molecule rose oxide. Although present in tiny amounts in rose oil, it has an odour threshold of 0.5 parts-per-billion and contributes more to the rose note than all other compounds except for damascone. Rose oxide is described as having a floral, green note and so important that a stamp with its molecular structure printed on it was issued when the compound was first isolated from the oil of Bulgarian roses. Rose oxide is a high value fine chemical because it takes 3 tonnes of rose blossoms to generate 1 kg of rose oil which contains <0.1% rose oxide. Material isolated from natural sources is expensive ($7,000 per kg). Commercially, rose oxide is produced by chemical routes from citronellol; one route uses bromine while others require reagents that are polluting to produce and use. The aim of this project is to develop a biological process to rose oxide from citronellol, with the key step being the oxidation of a specific carbon-hydrogen bond in citronellol. These bonds are chemically inert, which leads to more complex routes or more polluting processes in order to use citronellol as feedstock. We have developed enzyme variants capable of carrying out this critical step in water at ambient temperature. The industry partner for the project is in the process of taking this to commercial scale rose oxide production by a sustainable and non-polluting biotechnological process. The purpose of this project is to develop more active enzymes and alternative feedstocks based on citronellol in order to make the rose oxide process even more efficient and productive. Advanced computational methods will also be applied to help guide enzyme design and process development.