The instant invention describes methods of separating or preferentially synthesizing dimers which are linked via at least one interchain disulfide linkage from dimers which are not linked via at least one interchain disulfide linkage from a mixture comprising the two types of polypeptide dimers. These forms can be separated from each other using hydrophobic interaction chromatography. In addition, the invention pertains to connecting peptides that result in the preferential biosynthesis of dimers that are linked via at least one interchain disulfide linkage or that are not linked via at least one interchain disulfide linkage. The invention also pertains to compositions in which a majority of the dimers are linked via at least one interchain disulfide linkage or are not linked via at least one interchain disulfide linkage. The invention still further pertains to novel binding molecules, e.g., comprising connecting peptides of the invention.