Heterobifunctional reagents and conjugates with oxaalkylene units for amphiphilic bridge structures

A conjugate substance (A-B-A'), where A and A' are residues from organic compounds F and F'; at least one of which being a polymer (carrier) and said compounds having properties that are retained in the conjugate and -B- being a bridge that covalently binds A to A'. The bridge -B- comprises the structure -SrRCONHCH2CH2(OCH2CH2)nO(CH2)mCOY- (I); (i) n is often an integer 1-20 that is uniform for bridges linking identically located positions in individual molecules of the substance; (ii) m = 1 or 2; (iii) R = an alkylene group (1-4 carbon atoms) that possibly is substituted with one or more (1-3) hydroxy(OH) groups; (iv) = sulfur in the form of a thioether (r = 1) or disulfide (r = 2), and Sr binding to saturated carbon atoms in both directions; (v) Y is -NH-, -NHNH- or -NHN=CH- that in their left ends bind to CO and in their right ends to saturated carbon atom or to a carbonyl group (only -NHNH-). A bifunctional coupling reagent complying with the formula Z1RCONHCH2CH2(OCH2CH2)nO(CH2)mZ'1 (III); (i) n is an integer, often 1-20; (ii) m is an integer 1 or 2, preferably 1; (iii) Z1 = a SH-reactive electrophile or thiol (SH-) or protected thiol; (iv) R = an alkylene group (1-4 carbon atoms, that possibly is substituted with one or more (1-3) hydroxy(OH) groups; and (v) Z'1 is activated carboxy. A polyether complying with the formula XCH2CH2(OCH2CH2-)nOCH2Y (IV) where n is an integer 2-20, preferably 3-10. X is H2N- or substituted H2N- that is transformable to H2N-, preferably by hydrolysis or reduction. Y is carboxy or a group that is transformable to carboxy.