کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2052701 | 1074237 | 2005 | 6 صفحه PDF | دانلود رایگان |
Lipase L1 from Geobacillus stearothermophilus L1 contains an unusual extra domain, making a tight intramolecular interaction with the main catalytic domain through a Zn2+-binding coordination. To elucidate the role of the Zn2+, we disrupted the Zn2+-binding site by mutating the zinc-ligand residues (H87A, D61A/H87A, and D61A/H81A/H87A/D238A). The activity vs. temperature profiles of the mutant enzymes showed that the disruption of the Zn2+-binding site resulted in a notable decrease in the optimal temperature for maximal activity from 60 to 45–50 °C. The mutations also abolished the Zn2+-induced thermal stabilization. The wild-type enzyme revealed a 34.6-fold increase in stabilization with the addition of Zn2+ at 60 °C, whereas the mutant enzymes exhibited no response to Zn2+. Additional circular dichroism spectroscopy studies also confirmed the structural stabilizing role of Zn2+ on lipase L1 at elevated temperatures.
Journal: FEBS Letters - Volume 579, Issue 16, 20 June 2005, Pages 3461–3466