Relevant articles and documents
Mechanism of the hydrolysis of the sulfamate EMATE-an irreversible steroid sulfatase inhibitor
Spillane, William J. Malaubier, Jean-Baptiste
The kinetics of hydrolysis of the medicinally important sulfamate ester EMATE have been probed over a wide pH range and into moderately strong base (H_ region). Analysis of the pH/H_-rate profile, measurements of pKas, solvent-reactivity, kinetic isotope effects and determination of activation data reveal that in the pH range from ～1 to ～8 an SN2 (S) solvolytic mechanism is followed and after the pKa of EMATE (pKa ～9) is passed, a second pathway showing a first-order dependence on base operates and an E1cB mechanism is supported.
Characterization of 17β-hydroxysteroid dehydrogenase and regulators involved in estrogen degradation in Pseudomonas putida SJTE-1
Wang, Pingping Zheng, Daning Peng, Wanli Wang, Yanqiu Wang, Xiuli Xiong, Weiliang Liang, Rubing
In bacteria, the enzyme catalyzing the transformation of 17β-estradiol is considered the key enzyme for its metabolism, whose enzymatic activity and regulatory network influence the biodegradation efficiency of this typical estrogen. In this work, a novel 17β-hydroxysteroid dehydrogenase (17β-HSD) was characterized from the estrogen-degrading strain Pseudomonas putida SJTE-1, and two regulators were identified. This 17β-HSD, a member of the short-chain dehydrogenase/reductase (SDR) superfamily, could be induced by 17β-estradiol and catalyzed the oxidization reaction at the C17 site of 17β-estradiol efficiently. Its Km value was 0.068?mM, and its Vmax value was 56.26?μmol/min/mg; over 98% of 17β-estradiol was oxidized into estrone in 5?min, indicating higher efficiency than other reported bacterial 17β-HSDs. Furthermore, two genes (crgA and oxyR) adjacent to 17β-hsd were studied which encoded the potential CrgA and OxyR regulators. Overexpression of crgA could enhance the transcription of 17β-hsd, while that of oxyR resulted in the opposite effect. They could bind to the specific and different sites in the promoter region of 17β-hsd gene directly, and binding of OxyR could be released by 17β-estradiol. OxyR repressed the expression of 17β-hsd by its specific binding to the conserved motif of GATA-N9-TATC, while CrgA activated the expression of this gene through its binding to the motif of T-N11-A. Therefore, this 17β-HSD transformed 17β-estradiol efficiently and the two regulators regulated its expression directly. This work could promote the study of the enzymatic mechanism and regulatory network of the estrogen biodegradation pathway in bacteria.
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