Solubilization and Behavior Toward Sephadex of Rabbit Intestinal Sucrase

Rabbit intestinal sucrase maltase [EG 3.2.1.20] and leucine aminopeptidase [EC 3.4.1.1] were solubilized by digestion with papain [EC 3.4.4.10] without any loss of activities. In contrast, trehalase [EC 3.2.1.28] was not solubilized but, unlike the human enzyme, was not inactivated by papain. Sucrase and leucine aminopeptidase were also solubilized by other plant proteinases requiring sulfhydryl compounds, such as ficin [EC 3.4.4.12] and stem bromelain [EC 3.4.4.24]. However, thcywere not solubilized by the other proteinases tested (trypsin [EC 3.4.4.4], Nagarse [EC 3.4.4.16], Prozyme and probably cathepsins [EC 3.4.4.9 and 23]), pancreatic lipase [EC 3.1.1.3] or snake venom.

Solubilized sucrase and maltase were adsorbed on Sephadex G-200 at low temperature and released at higher temperature, but leucine aminopeptidase was not adsorbed. Sucrase was adsorbed more strongly on Sephadex gels with higher G-values.

It was suggested that adsorption of the enzymes is due to their affinities for gluco-sidic bonds in Sephadex and, not to an electrostatic interaction between them and Sephadex.