Protonation of the Acidic Residues in the Transmembrane Cation-Binding Sites of the Ca2+ Pump

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• 作者：Yuji Sugita ; Naoyuki Miyashita ; Mitsunori Ikeguchi ; Akinori Kidera ; and Chikashi Toyoshima
• 刊名：Journal of the American Chemical Society
• 出版年：2005
• 出版时间：May 4, 2005
• 年：2005
• 卷：127
• 期：17
• 页码：6150 - 6151
• 全文大小：143K
• 年卷期：v.127,no.17(May 4, 2005)
• ISSN：1520-5126

文摘

The ionization states of the acidic residues around the Ca²⁺-binding sites of sarcoplasmic reticulum Ca²⁺ ATPase are studied by continuum electrostatic calculations and all-atom molecular dynamics simulations with explicit solvent and phospholipids. The two methods consistently indicate that Glu58 and Glu908 are protonated at neutral pH. The Ca²⁺ coordination and the H-bonds formed by the protonation of Glu58 and Glu908 are stable in an MD simulation, whereas the H-bonds are disrupted and the Ca²⁺ coordination geometry is severely altered in another simulation treating these residues unprotonated. The results clearly indicate that the H-bonds formed by protonation of Glu58 and Glu908 provide extra stability for the Ca²⁺-binding sites of Ca²⁺ ATPase.