ABSTRACT
Removal of proteins from natural rubber (NR) may be essentially concerned with methods on how to control interactions between the rubber and proteins in the latex stage (i.e., chemical and physical interactions). The former is cleaved with proteolytic enzyme such as alkaline protease (Eng et al., 1993) and the latter is denatured with urea, which may change conformation of the proteins (Creighton, 1984). In the previous work (Eng et al., 1992; Fernando et al., 1985; Fukushima et al., 1998), the removal of proteins was mainly made in the latex stage by enzymatic deproteinization to remove proteins present on the surface of the rubber particle as a dispersoid. After the enzymatic deproteinization, the nitrogen content of NR was reduced to less than 0.02 wt%, which was about 1/20 of that of the untreated NR. Despite the significant decrease in the nitrogen content, however, problems still exist, that is, both a long incubation time necessary for the enzymatic deproteinization (i.e., more than 24 hr),
and remaining proteins, peptides, or amino acid sequences. It is, thus, quite important to establish a novel procedure to remove the proteins from NR rapidly and efficiently.
