Total direct chemical synthesis and biological activities of human group IIA secretory phospholipase A2

Human group IIA secretory phospholipase A2 (hGIIA sPLA2) is reported to be involved in inflammation, since its expression level is enhanced under various inflammatory conditions. In this work, we report the total chemical synthesis of this enzyme (124 amino acids) by solid-phase method. The identity of the protein, in denatured or folded (7 disulphide bonds) forms, was confirmed by electrospray MS. Synthetic sPLA2 possesses the same circular dichroism spectrum, enzymic activity in hydrolysing different phospholipid substrates, and inhibitory effect in thrombin formation from prothrombinase complex as the recombinant sPLA2. Furthermore, LY311727, a reported specific hGIIA sPLA2 inhibitor, is able to inhibit the synthetic and the recombinant enzymes with the same efficiency. This study demonstrates that chemically continuous solid phase synthesis is an alternative and less time-consuming approach to producing small, structurally folded and fully active proteins of up to 124 amino acids, such as hGIIA sPLA2. Moreover, this technique provides more flexibility in analogue synthesis to elucidate their physiological functions and pathological effects.