. Author manuscript; available in PMC: 2009 Dec 22.

Published in final edited form as: Biochemistry. 2006 May 9;45(18):5800–5816. doi: 10.1021/bi060217r

TABLE 4. Binding properties of OS₂ and its mutants to M-type and N-type receptors.

Competition binding assays between iodinated OS₂ and unlabeled mutants or chimeras were performed on recombinant M-type receptor or N-type receptors from mouse brain membranes and Hela P4 cell lysates. The K_0.5 value is defined as the concentration of sPLA₂ competitor which inhibits 50% of the specific binding. K_0.5 values are representative of at least three independent experiments with SEM values lower than 30%.

sPLA₂s	K_0.5 value
sPLA₂s	Rabbit M-type	Mouse M-type	Mouse N-type	HelaP4 N-type
	nM
Venom OS₂	0.009	0.07	0.011	0.02
rec OS₂ WT	0.009	0.07	0.011	0.02
OS₂ H48Q	0.021	0.19	0.53	1.2
OS₂ D49K	0.026	0.49	13.5	0.96
OS₂ G30S	0.035	0.2	200	400
OS₂ K31L-R34S	0.008	0.047	0.045	0.028
N-terminal chimera	0.19	1.4	>500	>500
Central chimera	0.037	2.2	>300	>300
C-terminal chimera	0.024	0.03	2	7.5
venom OS₁	0.1	0.15	>1000	>1000

TABLE 4. Binding properties of OS2 and its mutants to M-type and N-type receptors.

TABLE 4. Binding properties of OS₂ and its mutants to M-type and N-type receptors.