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Guinea pig plasma murinoglobulin. Purification and some properties
Biological Chemistry Hoppe-Seyler
|July 1, 1986
Summary
Guinea pig murinoglobulin, a plasma protein, inhibits proteolysis but stimulates amidolysis. Its proteinase inhibitory function is weaker than its mouse counterpart.
Area of Science:
- Biochemistry
- Proteomics
- Comparative immunology
Background:
- Murinoglobulin is a mouse plasma protein with alpha-macroglobulin-like properties.
- Alpha-macroglobulins are key regulators of protease activity in plasma.
Purpose of the Study:
- To investigate the presence and properties of murinoglobulin in guinea pig plasma.
- To compare the functional characteristics of guinea pig murinoglobulin with its mouse homologue.
Main Methods:
- Purification of murinoglobulin from guinea pig plasma.
- Assays for proteolytic and amidolytic activities using various substrates and proteases.
- Analysis of structural changes upon interaction with trypsin and methylamine treatment.
Main Results:
- Guinea pig murinoglobulin was purified as a single 180-kDa polypeptide chain with 18% carbohydrate content.
- It inhibited trypsin and thermolysin but stimulated trypsin and Staphylococcus aureus V8 protease amidolytic activity.
- Heat treatment abolished inhibitory activity but partially retained amidolytic activity.
- Guinea pig murinoglobulin exhibited weaker proteinase inhibitory capacity compared to mouse murinoglobulin.
- Interaction with trypsin and methylamine treatment revealed one thiol group unmasking per molecule.
Conclusions:
- Guinea pig murinoglobulin shares structural similarities with alpha-macroglobulins but exhibits distinct functional properties.
- The proteinase inhibitory function of guinea pig murinoglobulin is significantly weaker than that of the mouse homologue.
- Differential effects on proteolysis and amidolysis suggest complex regulatory roles for murinoglobulin.