The present invention relates to an isolated lysyl oxidase which is able to catalyze the oxidative deamination of lysyl groups in proteins or peptides to the corresponding aldehydes, with the subsequent reduction of O2 to H2O2 whereby the lysyl oxidase (a) shows a ratio of between lysyl oxidase activity for Ac-Gly-Lys-OMe and lysyl oxidase activity for benzylamine of at least 1.1, preferably at least 1.3, more preferably of at least 1.4 whereby the activities are determined at 37 degrees Celsius and an pH of 7.0; and. (b) has an optimum activity at a temperature of between 0 and 60 degrees Celcius.