کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1926636 | 1536470 | 2008 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Characterization of the palytoxin effect on Ca2+-ATPase from sarcoplasmic reticulum (SERCA)
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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
The effect of palytoxin was studied in a microsomal fraction enriched in longitudinal tubules of the sarcoplasmic reticulum membrane. Half-maximal effect of palytoxin on Ca2+-ATPase activity yielded an apparent inhibition constant of approx. 0.4 μM. The inhibition process exhibited the following characteristics: (i) the degree of inhibition was dependent on membrane protein concentration; (ii) no protection was observed when the ATP concentration was raised; (iii) dependence on Ca2+ concentration with a decreased maximum catalytic rate; (iv) it occurred in the absence of Ca2+ ionophoric activity. Likewise, the inhibition mechanism was linked to: (i) rapid enzyme phosphorylation from ATP in the presence of Ca2+ but lower steady-state levels of phosphoenzyme; (ii) more drastic effect on phosphoenzyme levels when the toxin was added to the enzyme in the absence of Ca2+; (iii) decreased phosphoenzyme levels at saturating Ca2+ concentrations; (iv) no effect on kinetics of phosphoenzyme decomposition. The palytoxin effect is related with lock of the enzyme in the Ca2+-free conformation so that progression of the catalytic cycle is impeded.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Archives of Biochemistry and Biophysics - Volume 478, Issue 1, 1 October 2008, Pages 36-42
Journal: Archives of Biochemistry and Biophysics - Volume 478, Issue 1, 1 October 2008, Pages 36-42
نویسندگان
Ramón Coca, Fernando Soler, Francisco Fernández-Belda,