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

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

Volume: 13 Issue: 1

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

Affiliation:

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

Abstract: 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.

Cite this article as:

Tan B., Qin B. S.-, Chen E. M.-, Cang X. H.- and Zhang J. H.-, Ca2+ Binding Effects on the C2 Domain Conformation of Human Cytosolic Phospholipase A2, Protein & Peptide Letters 2006; 13(1) . https://dx.doi.org/10.2174/092986606774502045