甾类激素是一大类在生物的发育、免疫、性别决定等重要生理过程中发挥调控作用的亲脂性分子，它们的生物合成与代谢过程是由多种还原酶、脱氢酶、裂解酶和芳香化酶所组成的大分子功能簇来实现的。该簇中酶之间活性的平衡决定了各种甾类分子在体内的水平，阐明这些生物大分子行使功能的结构基础不仅是了解甾类激素调控的细胞信号转导过程的关键，而且可以为以甾类激素生物合成通路为靶点的医疗方案提供药物设计与优化的指导。作为以亲脂性分子为底物和产物的功能大分子，参与甾类生物合成的酶包括大量疏水性膜蛋白，其结晶与结构解析存在较大的复杂性。为解决膜蛋白结构研究中存在的晶体微小、衍射能力低下以及需要海量晶体筛选的困难，光束线站必须经升级改造以具备更小光束直径、更高光束亮度和更强大的自动化数据采集和处理能力。所构建的强化线站可在针对甾类激素合成大分子功能簇的晶体学研究中进行实际验证和调整，从而能够满足膜蛋白晶体学所带来的挑战。

Steroid hormone is a class of lipophilic molecules regulating important physiological process, such as development, immunity and sexual determination, and their biosynthesis and metabolism are catalyzed by a macromolecular cluster consisted of various reductases, dehydrogenases, lyases and aromatases. The activity balance among the enzymes in this cluster contributes to the physiological levels of steroid hormones, making the structural basis for their functions not only a key to understanding the signal transductions mediated by.steroid hormones, but also a guide to design and optimization of medicines targeting on steroid hormone biosynthesis pathway. Recognizing and binding to the lipophilic molecules as substrates and products, enzymes involving in steroid hormone biosynthesis comprise many hydrophobic membrane proteins which cause difficulties in crystallization and structure determination. In order to solve the problems in studies on membrane protein structures such as tiny crystal size, low diffraction and large sample amount in screening, routine beamlines should be upgraded to generate x-ray beam with smaller size and higher intensity, as well as more powerful automatic data collecting and processing. The enhanced beamlines will be validated for their functions during the proposed structural studies on steroid hormone biosynthesis pathway and optimized accordingly, thereby meeting the novel challenge in membrane protein crystallography.