Subcellular immuno-localization, amino acid composition and partial amino acid sequences of α-l,4-glucan phosphorylase of Gracilaria spp (Rhodophyta)

Antibodies have been raised against an α-l,4-glucan phosphorylase (EC 2. 4. 1. 1) purified from the red alga Gracilaria chilensis. Localization of α-l,4-glucan phosphorylase in thin sections of G. chilensis and G. tenuistipitata was performed using immuno-gold labelling and transmission electron microscopy. The enzyme was localized in the cytosol and around the cytosolic starch granules of the algal cells. The labelling was not associated with the chloroplast or the cell wall. Amino acid composition of the red algal phosphorylase was quite similar to that of potato tuber and rabbit muscle phosphorylases. Partial amino acid sequences showed 48, 54 and 65% homology with the rabbit, potato and Escherichia coli enzymes, respectively.