alpha-Cobratoxin (1-24) amide

Formula : C105-H162-N32-O39-S2
CAS : 147710-70-1 

Consists of amino terminal loop.

alpha-Codeimethine

Formula : C19-H23-N-O3
CAS : 23950-06-03 

Impurity found in semi-synthetic codeine base.

alpha-Conotoxin sii

Formula : C66-H101-N21-O26-S6
CAS : 143294-31-9 

From Conus striatus; has 3 disulfide bonds (instead of two), has no net positive charge, and has a free C-terminus.