We investigated the surface behavior of gum Arabic (GA) as well as its effects on the lipolytic activity of human pancreatic lipase (HPL) and Humicola lanuginosa lipase (HLL), using emulsions of triacylglycerols (TAG) with various chain lengths. The effects of GA on the interfacial binding of HPL were also investigated. In the presence of 4 mM sodium taurodeoxycholate (NaTDC), GA (3% w/v, final concentration) had no effect on the HPL activity measured in the presence of colipase, whatever the type of TAG used. However, in the absence of bile salts or at low bile salt concentrations, GA inhibited the HPL activity when trioctanoin (TC8) and purified soybean oil (PSO) were used as substrates. At 3% (w/v, final concentration), GA strongly desorbed pure HPL from the TC8 interface and the classical anchoring effect of colipase was clearly observed. Both crude and dialyzed GA solutions were found to be highly tensioactive at the air-water as well as the oil-water interface using the drop technique. In conclusion, GA, or a putative contaminant present in GA, was found to be surface active and to have similar effects to those of bile salts on the interfacial binding and activity of HPL.
Copyright 2001 Academic Press.