| abstract |
A reagent having the general formula of General Formula I: (see Formula I) wherein group Z comprises a spacer selected from an aliphatic chain up to about 6 carbon equivalents in length, an unbranched aliphatic chain of from about 6 to 18 carbon equivalents in length with at least one of an intermediate amide and a disulfide moiety, and a polyethylene glycol chain of from about 3 to 12 carbon equivalents in length; wherein group R is an electrophilic or nucleophilic moiety suitable for reaction of the reagent with a biologically active species; and wherein group Q is one of nothing at all, an amide, a methyl amide, a methylene, an ether, a thioether, a methyl ether, and a methyl thioether moiety. Also, a conjugate, a bioconjugate and a method of conjugating. |