Substituted 2-iminothiolanes: reagents for the preparation of disulfide cross-linked conjugates with increased stability.
Much attention has been focused recently on the stability of immunotoxin (antibody-toxin) conjugates linked by a disulfide bridge. Conflicting reports have appeared regarding the in vivo stability of such conjugates prepared with the two most commonly used cross-linking reagents, SPDP and 2-iminothiolane. We have developed (i) a series of reagents based on 2-iminothiolane substituted at the 4- and/or 5-positions (X2ITs) which, based on model studies with simple amines, should show enhanced disulfide stability when conjugated with antibodies or other proteins and (ii) a real-time method for monitoring the rate and extent of conjugation of these reagents with amino groups. Depending upon the substituent, the stability of model-activated disulfides relative to unsubstituted 2-iminothiolane was increased from 5- to 4000-fold as measured by glutathione-induced release of thionitrobenzoic acid. This family of cross-linking reagents should allow the construction of disulfide cross-linked toxin, drug, or enzyme conjugates with enhanced stability in vivo.
Goff
D A
DA
Department of Biological Chemistry, XOMA Corporation, Berkeley, California 94710.
Carroll
S F
SF
D055598:Chemical Phenomena; D002621:Chemistry; D003432:Cross-Linking Reagents / Q000737:chemistry*; D003500:Cyclization; D004220:Disulfides / Q000737:chemistry*; D004228:Dithionitrobenzoic Acid; D004355:Drug Stability; D005998:Glycine / Q000737:chemistry; D007096:Imidoesters / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009570:Nitriles / Q000737:chemistry; D009579:Nitrobenzoates; D013056:Spectrophotometry, Ultraviolet; D013438:Sulfhydryl Compounds
D003432:Cross-Linking Reagents; D004220:Disulfides; D007096:Imidoesters; D009570:Nitriles; D009579:Nitrobenzoates; D013438:Sulfhydryl Compounds; C011136:thionitrobenzoic acid; C005905:methyl 4-mercaptobutyrimidate; D004228:Dithionitrobenzoic Acid; D005998:Glycine