Identification and characterization of mature beta-hexosaminidases associated with human placenta lysosomal membrane.

Hex (beta-hexosaminidase) is a soluble glycohydrolase involved in glycoconjugate degradation in lysosomes, however its localization has also been described in the cytosol and PM (plasma membrane). We previously demonstrated that Hex associated with human fibroblast PM as the mature form, which is functionally active towards G(M2) ganglioside. In the present study, Hex was analysed in a lysosomal membrane-enriched fraction obtained by purification from highly purified human placenta lysosomes.

Enhancement of lysosomal glycohydrolase activity in human primary B lymphocytes during spontaneous apoptosis.

It has been shown that lysosomes are involved in B cell apoptosis but lysosomal glycohydrolases have never been investigated during this event. In this study we determined the enzymatic activities of some lysosomal glycohydrolases in human tonsil B lymphocytes (TBL) undergoing in vitro spontaneous apoptosis. Fluorimetric methods were used to evaluate the activities of beta-hexosaminidases, alpha-mannosidase, beta-mannosidase, alpha-galactosidase, beta-glucuronidase and alpha-fucosidase.

Defective platelet beta-N-acetyl hexosaminidase content and release in chronic myeloproliferative disorders.

Background And Objectives: Abnormalities of platelet function or structure are a hallmark of chronic myeloproliferative disorders (MPD). In vivo platelet activation with the release of alpha- and delta-granules in the circulation is one of the most frequently described alterations in MPD. Platelets contain and release upon activation also lysosomes, and in particular beta-N-acetylhexosaminidase (Hex).

Identification of plasma membrane associated mature beta-hexosaminidase A, active towards GM2 ganglioside, in human fibroblasts.

Mature beta-hexosaminidase A has been found associated to the external leaflet of plasma membrane of cultured fibroblasts. The plasma membrane association of beta-hexosaminidase A has been directly determined by cell surface biotinylation followed by affinity chromatography purification of the biotinylated proteins, and by immunocytochemistry. The immunological and biochemical characterization of biotinylated beta-hexosaminidase A revealed that the plasma membrane associated enzyme is fully processed, suggesting its lysosomal origin.

Biochemical and immunological characterization of pollen-derived beta-galactosidase reveals a new cross-reactive class of allergens among Mediterranean trees.

Background: The most potent allergens in the Spermatophytae family exhibit significant homology with enzymes. Some of these are though to be involved in pectin metabolism, recognition of compatible stigma and delivery of sperm cells to the ovule.

Objective: To test if glycohydrolase activities from some Mediterranean tree pollens could act as allergens in sensitized hosts.