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The multiple forms of alpha-D-mannosidase in human plasma
The Biochemical Journal
|June 1, 1979
Summary
Human plasma contains four forms of intermediate alpha-D-mannosidase, with distinct molecular weights and concanavalin A affinities. Three forms are unique to plasma, unlike the minor liver-like form.
Area of Science:
- Biochemistry
- Enzymology
- Human Physiology
Background:
- Acidic alpha-D-mannosidase is an enzyme found in human tissues.
- Previous studies indicated multiple forms of this enzyme exist, but their characterization and distribution were unclear.
Purpose of the Study:
- To characterize the intermediate acidic alpha-D-mannosidase forms in human plasma.
- To compare plasma forms with those found in human liver.
- To propose a classification system for plasma alpha-D-mannosidase forms.
Main Methods:
- Chromatography using concanavalin A-Sepharose.
- Gel filtration with Sephadex G-200 and Sepharose 6B.
- Ion-exchange chromatography on DEAE-cellulose.
Main Results:
- Four distinct intermediate alpha-D-mannosidase forms were identified in human plasma based on molecular weight and concanavalin A affinity.
- Three of these forms (over 90% of activity) appear specific to plasma.
- A minor plasma form (approx. 7% activity) closely resembles neutral alpha-D-mannosidase found in liver.
Conclusions:
- A classification system for intermediate alpha-D-mannosidase in human plasma is proposed, based on molecular weight and concanavalin A affinity.
- The majority of intermediate alpha-D-mannosidase in plasma is distinct from liver forms.
- Further research may clarify the functional significance of these distinct enzyme forms.