POSSIBLE MECHANISM FOR THE INHIBITION OF LECTIN-ERYTHROCYTE INTERACTION IN PRESENCE OF ENDOGENOUS LECTIN RECEPTOR

The presence of hydrophobic sites in the lectin-I molecule was indicat ed by hydrophobic probes like 1-anilinonapthalene-8-sulfonic acid (ANS ), 2-p-toluidinyl napthalene-sulfonic acid (TNS), N-phenyl-1-napthylam ine (NA) and rose bengal (RE). This was further confirmed by amino aci d modifications in the hydrophobic region of the lectin-I molecule. Th e binding of ANS, TNS, NA and RE to lectin-I was affected in the prese nce of NaCl. The involvement of hydrophobic interactions in rice-bean lectin-I-endogenous lectin receptor (ELR) complex were indicated by al terations in the circular dichroism and fluorescence emission spectra. The percentage of beta-conformation (55-63%) of lectin-I was decrease d by addition of ELR. ELR on reacting with lectin-I reduced the fluore scence emissions of the hydrophobic probes while fluorescence emission of ANS, TNS, NA and RE were greatly enhanced in presence of lectin-I alone. N-aceyl-galactosamine did not change the fluorescence emissions of any of the hydrophobic probes in presence or in absence of lectin- I. This demonstrates that carbohydrate and hydrophobic sites may be di fferent and non-interacting. It is proposed that the ELR in reacting w ith lectin-I, induced conformational changes in the lectin-I molecule and thereby affected its erythroagglutinating activity with human bloo d group ''A'' erythrocytes.