Format

Send to

Choose Destination
See comment in PubMed Commons below
Glycoconj J. 2001 May;18(5):407-18.

Different behavior of ghost-linked acidic and neutral sialidases during human erythrocyte ageing.

Author information

  • 1Department of Medical Chemistry and Biochemistry, the Medical School, University of Milan, Italy.

Abstract

Acidic and neutral sialidases (pH optimum 4.7 and 7.2, respectively) were assayed on human circulating erythrocytes during ageing. The assays were performed on intact erythrocytes and resealed erythrocyte ghost membranes. From young to senescent erythrocytes the acidic sialidase featured a 2.7-fold and 2.5-fold decrease in specific activity when measured on intact cells or resealed ghost membranes, whereas the neutral sialidase a 5-fold and 7-fold increase, respectively. The Ca2+-loading procedure was employed to mimic the vesiculation process occurring during erythrocyte ageing. Under these conditions the released vesicles displayed an elevated content of acidic sialidase, almost completely linked through a glycan phosphoinositide (GPI) anchor but no neutral sialidase activity, that was completely retained by remnant erythrocytes together with almost all the starting content of sialoglycoconjugates. The loss with vesiculation of acidic sialidase with a concomitant relative increase of neutral sialidase was more marked in young than senescent erythrocytes. The data presented suggest that during ageing erythrocytes loose acidic sialidase, and get enriched in the neutral enzyme, the vesiculation process, possibly involving GPI-anchors-rich membrane microdomains, being likely responsible for these changes. The enhanced neutral sialidase activity might account for the sialic acid loss occurring during erythrocyte ageing.

PMID:
11925508
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Loading ...
    Write to the Help Desk