Histidine biosynthesis

Histidine is synthesized from phosphoribosyl pyrophosphate (PRPP), which is produced in the pentose phosphate pathway. The first step in the pathway is the condensation of PRPP and ATP by ATP-phosphoribosyl transferase (HIS1). HIS4 then hydrolyzes phosphoribosyl-ATP, which produces phosphoribosyl-AMP (PRAMP). Next, HIS4 catalyzes the formation of phosphoribosylformiminoAICAR-phosphate, which is converted to phosphoribulosylformimino-AICAR-P by the HIS6 gene product. HIS7 splits phosphoribulosylformimino-AICAR-P to form d-erythro-imidazole-glycerol-phosphate. HIS3 forms imidazole acetol-phosphate releasing water. HIS5 then makes l-histidinol-phosphate, which is hydrolyzed by HIS2 making histidinol. HIS4 catalyzes the oxidation of l-histidinol to form l-histidinal. In the last step, l-histidinal is converted to l-histidine. Description adapted from [https://en.wikipedia.org/wiki/Histidine Wikipedia].

组氨酸的合成源自于焦磷酸核糖（PRPP），该物质在磷酸戊糖途径中生成。该途径的起始步骤为焦磷酸核糖与三磷酸腺苷（ATP）在ATP-焦磷酸核糖转移酶（HIS1）的催化下发生缩合反应。随后，HIS4酶催化磷核糖-ATP的水解，生成磷核糖-腺苷酸（PRAMP）。紧接着，HIS4酶催化生成焦磷酸核糖亚氨甲酰基-AICAR-磷酸，该物质经HIS6基因产物转化成焦磷酸核糖亚氨甲酰基-AICAR-P。HIS7酶将焦磷酸核糖亚氨甲酰基-AICAR-P分解，形成D-赤藓糖-咪唑甘油磷酸。HIS3酶形成咪唑乙酰磷酸，同时释放出水分子。随后，HIS5酶将L-组氨酸醇磷酸化，该化合物被HIS2酶水解，生成组氨酸醇。HIS4酶催化L-组氨酸醇的氧化，形成L-组氨酸醛。在最后一步，L-组氨酸醛被转化为L-组氨酸。该描述改编自[https://en.wikipedia.org/wiki/Histidine Wikipedia]。