Bioconjugate complexes

The invention provides novel bioconjugate complexes linking two bioactive species (which may be the same or different) wherein the linkage comprises at least one boron atom, e.g., at least one phenylboronic acid complex. The bioconjugate complex of the invention is preferably a compound of the general formula (A): BAS-L-Bc-L'-(Bc'-L'')n-BAS', wherein BAS and BAS' are bioactive species (wheich may be the same or different); L, L', and L'' and linkers (which may be the same or different); Bc and Bc' are phenylboronic acid complexes (which may be the same or different) of formula D-E or E-D wherein D is a phenylboronic acid moiety and E is phenylboronic acid complexing moiety, and n is 0 or 1. Also provided are reagents and semiconjugates for making the bioconjugate complexes of the invention, and kits and methods utilizing the bioconjugate complexes of the invention.