Characterization of Acid-Cyclodextrin Glycosyltransferase of an Alkalophilic Bacillus sp.

Three kinds of lectins (LOL-I, II and III) were isolated from seeds of Lathyrus odoratus (sweet pea) in a homogenous form. The three fractions agglutinated the erythrocytes of laying hens, and the agglutination was strongly inhibited by α-methyl d-mannoside and d-mannose. However, they did not agglutinate those of the males and nonlyaing hens, differing from concanavalin A which showed a similar binding specificity for monosaccharide to LOL and agglutinated all types of erythrocytes derived from chicken in this study. LOL–I and II had a molecular weight of 52,000 and both consisted of two large (20,000 daltons) and two small subunits (6000 daltons). LOL–III had a molecular weight of 55,000, and its subunit structure was different from those of LOL–I and II. The amino acid compositions of the three fractions were very similar. They contained large amounts of aspartic acid, threonine, serine and valine, but no cysteine or methionine. Circular dichroism measurements indicated that β-structure was a major secondary structure of these lectins. The addition of α-methyl d-mannoside or d-mannose had significant effects on the CD spectra in the near-ultraviolet region, but no detectable change was observed in the 200~250 nm region. LOL–I had two binding sites for d-mannose, and the association constant was about 1000 liters per mol.