Efficient Photocleavage of Lysozyme by a New Chiral Probe

Photocleavage of lysozyme and bovine serum albumin (BSA) by L-phenylalanine-1(1- pyrene)methylamide (PMA-L-Phe) is reported here. The chiral probe, PMA-L-Phe, has a positively charged side chain, while the previous probes carried a free carboxyl group. The yield of lysozyme cleavage by PMA-LPhe is increased to 57% when compared to the previous probes, while the yield of BSA cleavage is reduced to <5%. Sequencing studies indicated that PMA-L-Phe cleaves lysozyme at a single site, between residues Trp108-Val109. Absorption and fluorescence spectral data indicate that PMA-L-Phe binds to lysozyme and BSA with affinity constants (Kb) of 3.3x105 M-1 and 3.8x105 M-1, respectively.