Abstract
Sialidase activities have been studied in bovine thyroid using sialoglycolipids, sialoglycoproteins, sialo-oligosaccharides and fluorogenic 4-methylumbelliferyl-alpha-D-N-acetylneuraminate as substrates. No sialidase activity could be detected towards native glycoprotein substrates. From enzyme kinetics, effector data and more convincingly from subcellular studies it became clear that in bovine thyroid at least two sialidase activities were present, a sialyllactitol sialidase confined to the lysosomal membrane and a glycolipid sialidase residing in the plasma membrane and displaying the features of a true ectoenzyme. The lipid requirement for full enzyme activity supported the membrane bound character of both sialidase activities. A soluble sialidase activity could not be demonstrated. After solubilization by CHAPS treatment, partial purification of the sialyllactitol sialidase could be achieved by affinity chromatography (Sepharose diamino dipropylamino-N-acetylneuraminic acid). The purified enzyme was extremely labile. Titration of the sialidase preparation with amino acid modifying agents revealed that sulfhydryl- and tryptophanyl groups were essential for the sialidase action.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
