骨化二醇及骨化三醇生物合成研究进展

Biosynthesis of calcifediol and calcitriol: a review

摘要:

维生素D₃是对人体健康十分重要的维生素，可以促进肠道对钙的吸收、防止佝偻病等。骨化二醇[25(OH) VD₃]和骨化三醇[1α,25(OH)₂VD₃]是维生素D₃的两种活性衍生物，在防治骨质疏松及调节人的生理功能方面发挥着重要作用。目前，骨化二醇及骨化三醇的生产以化学合成居多，但化学合成具有产物产量低、副产物多以及对环境不友好等缺点。因此开发一种绿色、安全、对环境友好的生物催化合成途径显得尤为重要。本文综述了骨化二醇及骨化三醇的生物催化合成途径，并介绍了该途径中的关键酶P450酶，包括P450单加氧酶(cytochrome P450 monooxygenases, CYPs)和P450过加氧酶(unspecific peroxygenases, UPOs)。其中研究较为广泛的是P450单加氧酶，通过解析其催化作用机制，分析不同氧化还原伴侣适配以及关键氨基酸残基对酶催化活性的重要影响。此外，对利用H₂O₂驱动的UPOs的催化机理、高效异源表达策略以及H₂O₂的原位再生等方面也进行了总结，UPOs优势在于既不需要昂贵的辅因子也不需要氧化还原伴侣的参与，是十分有前景的生物催化剂。本文为进一步开发或改造相关P450酶来高效生产VD₃活性衍生物提供了重要的参考。

Abstract:

VD₃ is a crucial vitamin for human health, as it enhances calcium absorption in the intestines and prevent rickets. Calcifediol (25(OH) VD₃) and calcitriol (1α,25(OH)₂VD₃) are two derivatives of vitamin D₃ that play an important role in preventing and treating osteoporosis, as well as regulating human physiological functions. Currently, the production of calcifediol, and calcitriol primarily relies on chemical synthesis, which has disadvantages such as low product yield, numerous by-products, and environmental unfriendliness. Therefore, developing a green, safe, and environmentally friendly biocatalytic synthesis pathway is of utmost importance. This article mainly reviews the biocatalytic synthesis pathways of calcifediol, and calcitriol. The P450 enzymes, including P450 monooxygenases (cytochrome P450 monooxygenases, CYPs) and P450 peroxygenases (unspecific peroxygenases, UPOs), are crucial for the production of calcifediol and calcitriol. The catalytic mechanism of the extensively studied P450 monooxygenases, the selection of suitable redox partners, and the key residues involved in the enzyme’s catalytic activity are analyzed. In addition, the review explores H₂O₂-driven UPOs, including their catalytic mechanism, strategies for high heterologous expression, and in situ regeneration of H₂O₂. UPOs are regarded as highly promising biocatalysts because they can facilitate reactions without the need for expensive cofactors and redox partners. This review offers insights into the engineering of P450 for the efficient production of vitamin D₃ derivatives.