Omega-conotoxin MVIIC (MVIIC) blocks P/Q-type calcium channels with high 
affinity and N-type calcium channels with low affinity, while the highly 
homologous omega-conotoxin MVIIA blocks only N-type calcium channels. We wished 
to obtain MVIIC analogues more selective for P/Q-type calcium channels than 
MVIIC to elucidate structural differences among the channels, which discriminate 
the omega-conotoxins. To prepare a number of MVIIC analogues efficiently, we 
developed a combinatorial method which includes a random air oxidation step. 
Forty-seven analogues were prepared in six runs and some of them exhibited 
higher selectivity for P/Q-type calcium channels than MVIIC in binding assays.