The conditions for assay of beta-mannosidase activity in human chorionic villi (CV) were studied using the fluorogenic substrate 4-methylumbelliferyl-beta-D-mannopyranoside. A comparison of the biochemical properties of the CV beta-mannosidase with those of the enzyme from human cultured fibroblasts showed their similarity. Like the enzyme from skin fibroblasts, the CV 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 an early stage of development.

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The effect of exogenous and endogenous products storage in lysosomes on the activity and multiple forms of alpha-L-fucosidase from human skin fibroblasts was investigated. It was shown that sucrose load, modelling intralysosomal accumulation of nonhydrolyzable products, causes certain changes in secretion level of alpha-L-fucosidase and multiple forms' spectra of the intracellular and secreted enzymes. These changes were different for the enzyme from embryonal and postnatal normal fibroblasts. Some changes of secreted alpha-L-fucosidase isoforms' spectra were found in fibroblasts from a patient with Fabry's disease, characterized by the intralysosomal storage of di- and trihexosylceramides. The alterations of isoforms' profiles in Fabry fibroblasts at the early and late accumulation stages were similar to those in sucrose-loaded embryonal and postnatal fibroblasts, respectively. It is proposed that intralysosomal accumulation of nonhydrolyzable compounds influences the alpha-L-fucosidase posttranslational processing.

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