کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9882240 | 1536550 | 2005 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Activation of sphingomyelinase from Bacillus cereus by Zn2+ hitherto accepted as a strong inhibitor
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
بیوشیمی، ژنتیک و زیست شناسی مولکولی
زیست شیمی
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چکیده انگلیسی
Sphingomyelinase (SMase) from Bacillus cereus has been known to be activated by Mg2+, Mn2+, and Co2+, but strongly inhibited by Zn2+. In the present study, we investigated the effects of several kinds of metal ions on the catalytic activity of B. cereus SMase, and found that the activity was inhibited by Zn2+ at its higher concentrations or at higher pH values, but unexpectedly activated at lower Zn2+ concentrations or at lower pH values. This result indicates that SMase possesses at least two different binding sites for Zn2+ and that the Zn2+ binding to the high-affinity site can activate the enzyme, whereas the Zn2+ binding to the low-affinity site can inactivate it. We also found that the binding of substrate to the enzyme was independent of the Zn2+ binding to the high-affinity site, but was competitively inhibited by the Zn2+ binding to the low-affinity site. The binding affinity of the metal ions to the site for activating the enzyme was determined to be in the rank-order of Mg2+Â =Â Co2+Â <Â Mn2+Â <Â Zn2+. It was also demonstrated that these four metal ions competed with each other for the same binding site on the enzyme molecule.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Archives of Biochemistry and Biophysics - Volume 436, Issue 2, 15 April 2005, Pages 227-236
Journal: Archives of Biochemistry and Biophysics - Volume 436, Issue 2, 15 April 2005, Pages 227-236
نویسندگان
Shinobu Fujii, Hiromi Itoh, Ayumi Yoshida, Satoko Higashi, Hiroh Ikezawa, Kiyoshi Ikeda,