Removal of old protein layers from surfaces of works of art by new enzymes

Abstract

The aim of the present project is to set up bio-cleaning protocols in order to easily remove altered protein layers (e.g. animal glues) by enzymatic proteins (proteases). Protein molecules were isolated from marine invertebrate organisms, characterized by size exclusion highpressure liquid chromatography (Waters: SEC-HPLC, BioSuite 250 to 10㎛ SEC 7.5 x 300 mm) and their gelatinase activity analyzed by zymography on polyacrilamide gel. The remarkably proteolytic activity and the reaction temperature range of these enzymes, 4° to 37℃, made it possible to hypothesize their use in bioremediation projects. Tests were performed on protein coating found on some polychrome wooden artifacts exposed to different environmental conditions (temperature, humidity, UV radiation). Particularly, altered animal glue layers were removed by using these enzymes at“ room temperature” (19-25.5℃) without changing the temperature of the surface or of the enzyme solution. The results of the applications were satisfying since the removal of the protein layers was carried out in controlled conditions, conducted at the same temperature as that of the environments where the objects were exposed/stored. 　In conclusion, the hypothesis is that these enzymes will improve bio-cleaning efficiency even when used at low temperature instead of commercially available proteases, which are usually active at ≥ 37℃, thus respecting the aim of conservative restoration.