Enzyme-linked lectin assay (ELLA): Use of alkaline phosphatase-conjugated Griffonia simplicifolia B4 isolectin for the detection of [alpha]--galactopyranosyl end groups

Abstract

Alkaline phosphatase has been coupled to Griffonia simplicifolia I B4 isolectin using a one-step glutaraldehyde conjugation procedure. This enzyme-lectin conjugate (AP-GS I-B4) has been used to specifically detect plastic-bound natural and synthetic glycoproteins bearing [alpha]--galactopyranosyl end groups. The extent of reactivity of the AP-GS I-B4 with the glycoproteins appears to be proportional to the number of terminal galactosyl residues present. Furthermore, this assay, termed ELLA (enzyme-linked lectin assay), is specifically inhibitable by low-molecular-weight sugars containing terminal [alpha]--galactosyl groups. The ELLA reactions may be assayed rapidly and objectively by the use of commercially available ELISA-plate readers using standard filters.