Interaction between bovine serum albumin and alkoxy substituted phthalocyanines was studied by
means of electron absorption spectroscopy, fluorescence spectroscopy and viscosimetry. The binding
constants and binding distance were calculated. It was found that ZnPc(4-NH-CO-C 6 H 4 -OC 10 H 21 ) 4 pre-
vents twisting of BSA molecule and localizes between subdomains IB and IIA in protein globule.
ZnPc(4-NH-CO-C 6 H 4 -OC 6 H 13 ) 4 and ZnPc(4-NH-CO-C 6 H 4 -OC 8 H 17 ) 4 are located on the outer surface of the
protein globule. In the case of ZnPc(4-NH-CO-C 6 H 4 -OC 3 H 7 ) 4 it can be assumed that the phthalocyanine
molecule is in the immediate vicinity of the subdomains IB and IIA.
