Rubber oxygenase degradation assay by UV-labeling and gel permeation chromatography

Abstract

A versatile and robust end-group derivatization approach using oximes has been developed for the detection of oxidative degradation of synthetic polyisoprenes and polybutadiene. This method demonstrates broad applicability, effectively monitoring degradation across a wide molecular weight range through ultraviolet (UV)-detection coupled to gel permeation chromatography. Importantly, it enables the effective monitoring of degradation via derivatization-induced UV-maximum shifts, even in the presence of an excess of undegraded polyene, overcoming limitations previously reported with refractive index detectors. Notably, this oxime-based derivatization methodology is used in enzymatic degradation experiments of synthetic polyisoprenes characterized by a cis: trans ratio with the rubber oxygenase LcpK30. It reveals substantial UV absorption in derivatized enzymatic degradation products of polyisoprene with molecular weights exceeding 1000 g mol−1 - an unprecedented revelation for this enzyme's activity on such synthetic polyisoprenes. This innovative approach holds promise as a valuable tool for advancing research into the degradation of synthetic polyisoprenes and polybutadiene, particularly under conditions of low organocatalytic or enzymatic degradation activity. With its broad applicability and capacity to reveal previously hidden degradation processes, it represents a noteworthy contribution to sustainable polymer chemistry.