NEW PATHWAY OF ISOPRENOID BIOSYNTHESIS

SIR提供了Te-蛋氨酸；Ig是根本问题之一 在大分子中。结晶学是合适的可得性 解决位相问题所必需的重原子导数。这个 用碲标记蛋白质的能力。氨基酸 (碲蛋氨酸)在内部部位通过利用 蛋白质生物合成为x射线结晶学家提供了一种方便的 相移载体和核磁共振(核磁共振)光谱仪内部探针 用Te-125核磁共振研究结构/功能关系 光谱学。在此通信中，我们演示了部分 将蛋氨酸掺入大肠杆菌二氢叶酸中 还原酶(DBFR)，对活性或 底物结合。含有两个摩尔的酶Temet表现出 比活度为42个单位/毫克，结合比为1：1 甲氨蝶呤。

The SIR provided Te-Methionine; Ig One of the fundamental problems in macromol. crystallography is the availability of the suitable heavy-atom derivatives necessary to solve the phase problem. The ability to label a protein with a tellurium-contg. amino acid (telluromethionine) at internal sites through the utilization of protein biosynthesis supplies x-ray crystallographers a convenient phasing vehicle and NMR (NMR) spectroscopists an internal probe with which to study structure/function relationships via Te-125 NMR spectroscopy. In this communication we demonstrate the partial incorporation of telluromethionine into E. coli dihydrofolate reductase (DBFR) with no apparent perturbations to activity or substrate binding. Enzyme contains two moles TeMet exhibited a specific activity of 42 units/mg and a 1: 1 binding ratio with methotrexate.