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Protein & Peptide Letters


ISSN (Print): 0929-8665
ISSN (Online): 1875-5305

Ca2+ Binding Effects on the C2 Domain Conformation of Human Cytosolic Phospholipase A2

Author(s): B. Tan, S.- B. Qin, M.- E. Chen, H.- X. Cang and H.- J. Zhang

Volume 13, Issue 1, 2006

Page: [91 - 94] Pages: 4

DOI: 10.2174/092986606774502045

Price: $65


It has been reported that the cooperative binding of calcium ions indicated a local conformational change of the human cytosolic phospholipase A 2 (cPLA2) C2 domain (Nalefski et al., (1997) Biochemistry 36, 12011-12018). However its structural evidence is less known (Malmberg et al., (2003) Biochemistry 42, 13227-13240). In this letter, life-time decay and fluorescence quenching techniques were employed to compare the calcium-induced conformational changes. The life-time decay parameters and fluorescence quenching constant changes were small between the apo- and holo-C2 domains when tryptophan residue was excited at 295 nm. In contrast, the quenching constant change was large, from 0.52 M-1 for the apo-C2 to 8.8 M-1 for the holo-C2 domain, when tyrosine residues were excited at 284 nm. Our results provide new information on amino acid side chain orientation change at calcium binding loop 3, which is necessary for Ca2+ binding regulated membrane targeting of human cytosolic phospholipase A2.

Keywords: C2 domain, Cytosolic phospholipase A2, Fluorescence quench, Time-resolved fluorescence decay, Conformational change

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