R. Kliukiene et al., PHOTOINACTIVATION OF TRYPANOTHIONE REDUCTASE AND GLUTATHIONE-REDUCTASE BY A1-PHTHALOCYANINE TETRASULFONATE AND HEMATOPORPHYRIN, Biochemical and biophysical research communications, 218(2), 1996, pp. 629-632
The irradiation of Trypanosoma congolense trypanothione reductase (TR)
, human erythrocyte (HGR) and yeast glutathione reductase (YGR) with v
isible light in the presence of Al-phthalocyanine tetrasulfonate (AlPc
S(4)) or hematoporphyrin (Hp) caused a time-dependent inactivation of
these enzymes. TR was inactivated more rapidly than either HGR or YGR.
Half-maximal rates of inactivation were determined in the presence of
100 mu M Hp and 1.4-17 mu M AlPcS(4). The photosensitized irradiation
modified the disulfide substrate-binding sites;af these enzymes, most
likely the conserved catalytic histidine residue. In the dark, A1PcS,
acted as a reversible inhibitor competitive with the disulfide substr
ate of TR and HGR. These findings suggest the possible use of photosen
sitized irradiation for preventing the transmission of trypanosomiasis
by blood transfusion. (C)I996 Academic Press, Inc.