RECOGNITION OF SUBSTRATES BY IMMOBILIZED ALBUMIN MEMBRANES PREPARED FROM LANGMUIR-BLODGETT AND ENTRAPMENT METHODS - RESPONSE OF CIRCULAR-DICHROISM INDUCED BY D-TRYPTOPHAN AND L-TRYPTOPHAN

The change in the circular dichroism spectra induced by immersion of t he membranes into the aqueous tryptophan solution was measured using t he immobilized serum albumin membranes prepared by the Langmuir-Blodge tt (LB) method and the entrapment method. The alpha-helix content of t he albumin membranes prepared by the LB method was observed to decreas e on the immersion of the membranes into 0.01 M D-tryptophan solution, whereas the completely opposite tendency was observed when the albumi n membranes prepared from the entrapment method were used. The change in the circular dichroism originates from the conformational change of the immobilized albumin membranes induced by the binding between the albumin and tryptophan on the membranes. It is considered that orienta ted albumin on the LB film of poly (alpha-amino acid) makes the differ ent conformational responses to the tryptophan binding to the albumin compared to randomly located albumin in the immobilized albumin membra nes prepared by the entrapment method, because albumin on the LB film of poly (alpha-amino acid) was observed to be orientated from focal la ser scanning microscopic measurements.