E. coli nitroreductase NfsB (also called NfnB) has been studied extensively, largely due to its potential for cancer gene therapy. A homodimeric flavoprotein of 216 residues, it catalyses the reduction of nitroaromatics to cytotoxic hydroxylamines by NADH and NADPH and also the reduction of quinones to hydroxyquinones. Its role in vivo is not known but it is postulated to be involved in reducing oxidative stress. The crystal structures of the wild type protein and several homologues have been determined in the absence and presence of ligands, including nicotinate as a mimic of the headpiece of the nicotinamide cofactors. There is little effect on the overall structure of the protein on binding ligands, but, from the B factors, there appears to be a decrease in mobility of 2 helices near the active site. As a first step towards examining the dynamics of the protein in solution with and without ligand, we have assigned the backbone ¹³C, ¹⁵N, and ¹H_N resonances of NfsB and examined the effect of the binding of nicotinate on the amide ¹⁵N, and ¹H_N shifts.

大肠杆菌硝基还原酶 NfsB（也称为 NfnB）已被广泛研究，主要是由于其在癌症基因治疗方面的潜力。一种具有 216 个残基的同二聚体黄素蛋白，它催化 NADH 和 NADPH 将硝基芳烃还原为具有细胞毒性的羟胺，以及将醌还原为羟基醌。它在体内的作用尚不清楚，但据推测它与减少氧化应激有关。野生型蛋白质和几种同源物的晶体结构已在不存在和存在配体的情况下确定，包括作为烟酰胺辅因子头饰模拟物的烟酸盐。结合配体对蛋白质的整体结构几乎没有影响，但从 B 因素来看，活性位点附近的 2 个螺旋的移动性似乎有所降低。^{NfsB 的13} C、¹⁵ N 和¹ H _N共振并检查了烟酸盐结合对酰胺¹⁵ N 和¹ H _N位移的影响。