Membrane anchoring and surface distribution of glycohydrolases of human erythrocyte membranes

Abstract

The membrane anchoring of the following glycohydrolases of human erythrocyte plasma membranes was investi-Optimized fluorimetric methods for the assay of these enzymes were set up. Treatment of the ghost preparation with 1.0 mol/l (optimal concentration) NaCl caused release ranging from 4.2% ofTreatment with phosphoinositide-specific phospholipase C caused no liberation of any of the studied glycohydrolases. These results are consistent with the notion that the above glycohydrolases are differently anchored or associated with the erythrocyte plasma membrane, and provide the methodological basis for inspecting the occurrence of these enzymes in different membrane microdomains.z 2000 Federation of European Biochemical Societies.

Immunocytochemical and biochemical detection of alpha-L-fucosidase in Trypanosoma cruzi

“…The enzyme is also present in body fluids and in the plasma membrane, as reported for sperm cells (14,15) or human erythrocytes (16).…”

“…Immunocytochemical techniques and detection of enzymatic activity were used to demonstrate that at least 50% of the enzyme is associated with the cytoplasmic and plasma membranes. Although most of the a-L-fucosidase activity of virtually all mammalian tissues is in the soluble fraction, membrane-associated a-Lfucosidase has been described in rat testis and epididymal spermatozoa (14,29), in human sperm plasma membrane (15), and in human erythrocyte membranes (16).…”

“…The a-L-fucosidase from the membrane fraction of epimastigotes has a neutral pH optimum (pH 6.0-7.5), having no activity at acidic pH, in contrast to a-L-fucosidases isolated from lysosomes. A more neutral pH optimum was described for a-L-fucosidases from Corynebacterium, pH 8. foetus, pH 7.0 (32), and for the enzymes from rat sperm and erythrocytes (14,16).…”

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

“…These lipids play key role as signaling molecules in both physiological and pathological processes regulating cell-to-cell and/or cell-environment interactions [3,38]. Several recent studies revealed the presence of glycohydrolases not only in lysosomes but also at cell surface [5,18,39,40]. They stress the potential role of a remodelling of glycosphingolipids during cellular processes [6,7].…”

Age-related changes in erythrocyte membrane sulfhydryl groups and β-D-glucuronidase activity

“…Altered redox balance with increasing age can potentially affect the activity of any protein, since virtually all proteins contain cysteine and methionine; amino acids that are particularly susceptible to changes in oxidation reduction. Glycohydrolases, including β-D-glucuronidase, present on the plasma membrane of the erythrocytes, have been the subject of much investigation [7,8] due to their distinct modality of anchoring, non-homogeneous distribution on the membrane micro-domains, and their involvement in specific pathologies. Beta-Dglucuronidase hydrolyzes β-D-glucuronides to glucuronic acid and an aglycone, which may be in the form of an alcohol, another organic acid, an imine, or a thiol compound.…”