Physicochemical studies on two forms of Bengal gram lipoxygenase: Implication for structural differences.

Two forms of lipoxygenase have been isolated from Bengal gram (Cicer arieiinum) and purified to apparent
homogeneity. In sedimentation velocity experiments both forms showed a single symmetrical peak with an
s20,W value of 5.5 f 0.5 S. From the SDS-polyacrylamide gel electrophoresis and gel filtration data they
appeared to consist of a single polypeptide chain of identical size (M, = 95 000). The amino acid composition
was essentially identical except for the proline and isoleucine contents. Kinetically, the two forms were
quite distinct. The CD spectra of the two forms in the far-ultraviolet region were rather similar. However, in
the near-ultraviolet region there were discernible differences. Although the antibody raised against each of
them showed antigenic cross-reactivity, there was a perceptible difference in the cross-reaction with enzymes
from other legumes. The results imply elements of dissimilarity in the structure of these two forms.