1. Crystalline β-lactamase I from Bacillus cereus 569/H yielded only amino acids on acid hydrolysis, but crystalline β-lactamase II from the same organism yielded also substantial quantities of neutral sugars and amino sugars. 2. Analysis with an amino acid analyser indicated that the two enzymes were similar though not identical in overall amino acid composition. Analysis of neutral and amino sugars as their silyl derivatives by gas–liquid chromatography showed that the carbohydrate moiety of β-lactamase II contained residues of glucose, galactose, mannose, fucose, glucosamine and galactosamine. 3. After oxidation and hydrolysis both β-lactamases gave small amounts of cysteic acid. After treatment of inactive Zn2+-free β-lactamase II with N-ethylmaleimide or iodoacetate enzymic activity was not restored by the addition of Zn2+.
