Search

Conditions for assay of beta-mannosidase activity in human chorionic villi were studied using the fluorogenic substrate 4-methylumbelliferyl-beta-D-mannopyranoside. Comparison of the biochemical properties of the chorionic villi beta-mannosidase with those of the enzyme from human cultured fibroblasts showed their similarity. Like the enzyme from skin fibroblasts, the chorionic villi beta-mannosidase had rather high activity. Both enzymes had virtually the same pH optimum (4.2-4.7) and Km value. The data presented suggest that chorion biopsy specimens can be used for prenatal determination of beta-mannosidase activity at the early stage of development.

The activity of beta-mannanase from Bacillus subtilis was measured viscosimetrically and spectrophotometrically. As substrate galactomannane of Ceratonia siliqua was used. Relationships between the beta-mannanase activity and the substrate concentration as well as the enzyme content were investigated. The kinetic parameters of the enzymes obeying the Michaelis-Menten equation were calculated. It was found viscosimetrically that Vmax of the commercial enzyme preparation was 1.4 mucat/g (at pH 5.8 and 40 degrees) and Km was 0.6 mM. The viscosimetric method shows high sensitivity, whereas the spectrophotometric technique suits mass-scale analyses.

Twenty-three strains of soil microorganisms synthetizing extracellular mannanase were isolated on the medium containing baker's yeast mannan as the sole carbon source. Ten most active strains were identified with respect to their genera. These microorganisms proved capable to hydrolyze mannans, whose mannopyranose units were bound by alpha-1,2-and alpha-1,6-bonds. In addition, 5 of these strains were able to hydrolyze mannans whose mannose residues were bound by alpha-1,3-bond, and 2 strains could synthetize mannanase active towards yeast beta-mannane with 1,3 and 1,4 bonds. The strains tested showed a very low, if any, lytic activity towards yeast Saccharomyces and Candida. This gives evidence that mannanase is an enzyme unable to perform independently lysis of the yeast cell wall.