Hyman M R, Kim C Y, Arp D J
Department of Biochemistry, University of California, Riverside 92521.
J Bacteriol. 1990 Sep;172(9):4775-82. doi: 10.1128/jb.172.9.4775-4782.1990.
Carbon disulfide has long been recognized as a potent inhibitor of nitrification, and it is the likely active component in several nitrification inhibitors suitable for field use. The effects of this compound on Nitrosomonas europaea have been investigated, and the site of action has been determined. Low concentrations of CS2 (less than 400 microM) produced a time-dependent inhibition of ammonia-dependent O2 uptake but did not inhibit hydrazine-oxidizing activity. CS2 also produced distinct changes in difference spectra of whole cells. These results suggest that ammonia monooxygenase (AMO) is the site of action of CS2. Unlike the case for thiourea and acetylene, saturating concentrations of CS2 did not fully inhibit AMO, and the inhibition resulted in a low but significant rate of ammonia-dependent O2 uptake. The effects of CS2 were not competitive with respect to ammonia concentration, and the inhibition by CS2 did not require the turnover of AMO to take effect. The ability of CS2-treated cells to incorporate [14C]acetylene into the 28-kilodalton polypeptide of AMO was used to demonstrate that the effects of CS2 are compatible with a mode of action which involves a reduction of the rate of turnover of AMO without effects on the catalytic mechanism. It is proposed that CS2 may act on AMO by reversibly reacting with a suitable nucleophilic amino acid in close proximity to the active site copper.
长期以来，二硫化碳一直被认为是一种强效的硝化作用抑制剂，并且它可能是几种适用于田间使用的硝化抑制剂中的活性成分。已经对该化合物对欧洲亚硝化单胞菌的影响进行了研究，并确定了其作用位点。低浓度的二硫化碳（小于400微摩尔）对依赖氨的氧气摄取产生了时间依赖性抑制，但不抑制肼氧化活性。二硫化碳还使全细胞的差示光谱发生明显变化。这些结果表明，氨单加氧酶（AMO）是二硫化碳的作用位点。与硫脲和乙炔的情况不同，饱和浓度的二硫化碳并未完全抑制AMO，并且这种抑制导致依赖氨的氧气摄取速率较低但显著。二硫化碳的作用在氨浓度方面没有竞争性，并且二硫化碳的抑制作用不需要AMO的周转来生效。用经二硫化碳处理的细胞将[14C]乙炔掺入AMO的28千道尔顿多肽中的能力来证明，二硫化碳的作用与一种作用模式相一致，该模式涉及降低AMO的周转速率而不影响催化机制。有人提出，二硫化碳可能通过与活性位点铜附近合适的亲核氨基酸可逆反应而作用于AMO。
