Affinity of fructose 1,6-bisphosphate aldolase to glycosaminoglycans

ABSTRACT

Fructose 1,6-bisphosphate aldolase (FPA) was recently known as new member of heparin binding proteins and a new method for FPA purification has been proposed (Thanh Van Ta et all, J. Biochem. 125, 554-559,199) by measuring FPA - heparin binding inhibition caused by various glycosaminoglycans (GAGs), affinity of the two isoforms, aldolase A4 and C4, to the GAGs underphysiological ionic conditions was estimated. Among glycosaminoglycans employd, heparin was confirmed to be the unique one that could bind specifically these enzymes. In the lower ionic strength, the affinity order of both FPA isoforms (A4 and C4) to these GAGs appeared as heparin> chondroitin polysulfate> heparin sulfate > dermatan > chondrointin sulfate A > chondroin sulfate C. Employing the same techniques, the affinity of regioselectively desulfated heparins to FPA was estimated. Our results indicated that, among the sulfate groups is heparin, loss of N-sulfate group reduced most significantly the affinity to FPA A4 and C4. This sugests that FPA recognizes a specific heparin structure including the sulfo-amino group at C2 of the glucosamine residue as the vital factor in this interaction.