Cook A M, Laue H, Junker F
Fakultät für Biologie der Universität, Konstanz, Germany.
FEMS Microbiol Rev. 1998 Dec;22(5):399-419. doi: 10.1111/j.1574-6976.1998.tb00378.x.
Organosulfonates are widespread compounds, be they natural products of low or high molecular weight, or xenobiotics. Many commonly found compounds are subject to desulfonation, even if it is not certain whether all the corresponding enzymes are widely expressed in nature. Sulfonates require transport systems to cross the cell membrane, but few physiological data and no biochemical data on this topic are available, though the sequences of some of the appropriate genes are known. Desulfonative enzymes in aerobic bacteria are generally regulated by induction, if the sulfonate is serving as a carbon and energy source, or by a global network for sulfur scavenging (sulfate-starvation-induced (SSI) stimulon) if the sulfonate is serving as a source of sulfur. It is unclear whether an SSI regulation is found in anaerobes. The anaerobic bacteria examined can express the degradative enzymes constitutively, if the sulfonate is being utilized as a carbon source, but enzyme induction has also been observed. At least three general mechanisms of desulfonation are recognisable or postulated in the aerobic catabolism of sulfonates: (1) activate the carbon neighboring the C-SO3- bond and release of sulfite assisted by a thiamine pyrophosphate cofactor; (2) destabilize the C-SO3- bond by addition of an oxygen atom to the same carbon, usually directly by oxygenation, and loss of the good leaving group, sulfite; (3) an unidentified, formally reductive reaction. Under SSIS control, different variants of mechanism (2) can be seen. Catabolism of sulfonates by anaerobes was discovered recently, and the degradation of taurine involves mechanism (1). When anaerobes assimilate sulfonate sulfur, there is one common, unknown mechanism to desulfonate the inert aromatic compounds and another to desulfonate inert aliphatic compounds; taurine seems to be desulfonated by mechanism (1).
有机磺酸盐是广泛存在的化合物，无论是低分子量还是高分子量的天然产物，或是外源性物质。许多常见化合物都会发生脱硫反应，即便尚不确定所有相应的酶是否在自然界中广泛表达。磺酸盐需要转运系统才能穿过细胞膜，但关于这一主题的生理数据很少，生化数据也没有，不过一些相关基因的序列是已知的。需氧细菌中的脱硫酶一般在磺酸盐作为碳源和能源时受诱导调控，而当磺酸盐作为硫源时，则受一个全局硫清除网络（硫酸盐饥饿诱导刺激子）调控。目前尚不清楚厌氧菌中是否存在硫酸盐饥饿诱导刺激子调控。所检测的厌氧菌如果将磺酸盐用作碳源，可以组成型表达降解酶，但也观察到了酶的诱导现象。在磺酸盐的需氧分解代谢中，至少可以识别或推测出三种一般的脱硫机制：（1）激活与C-SO3-键相邻的碳原子，并在硫胺焦磷酸辅因子的协助下释放亚硫酸盐；（2）通过向同一碳原子直接加氧（通常是通过氧化作用）使C-SO3-键不稳定，并失去良好的离去基团亚硫酸盐；（3）一种未确定的、形式上的还原反应。在硫酸盐饥饿诱导刺激子的控制下，可以看到机制（2）的不同变体。厌氧菌对磺酸盐的分解代谢是最近才发现的，牛磺酸的降解涉及机制（1）。当厌氧菌同化磺酸盐硫时，对于惰性芳香族化合物脱硫有一种常见的、未知的机制，对于惰性脂肪族化合物脱硫则有另一种机制；牛磺酸似乎是通过机制（1）进行脱硫的。
