ALTERATION OF THE SUBSTRATE-SPECIFICITY OF HUMAN LYSOZYME BY SITE-SPECIFIC INTERMOLECULAR CROSS-LINKING

Human lysozyme dimers were prepared by the intermolecular cross-linkin g of the monomer that contained the mutation of either Arg(41) to Cys or Ala(73) to Cys with a divalent maleimide compound. Among the three kinds of possible dimers only R41C-R41C dimer, in which the two cataly tic clefts can come close to each other due to the proximity of the co njugation site to the active sites, turned out to be 2.3 times more sp ecific to a polymer substrate, ethylene glycol chitin, as compared to an oligomer substrate, PNP-(GlcNAc)(5). The result indicates that it i s possible to alter the substrate specificity of an enzyme by artifici ally controlling the orientation of the active sites.