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Size and shape of two intestinal dipeptidases.
International Journal of Peptide and Protein Research
|February 1, 1978
Summary
Physicochemical analysis of pig small intestine dipeptidases reveals they are dimers. Both glycyl-L-leucine hydrolase and aminoacyl-L-proline hydrolase exhibit similar physicochemical properties and molecular structures.
Area of Science:
- Biochemistry
- Enzymology
- Proteomics
Background:
- Dipeptidases play crucial roles in protein digestion and amino acid absorption.
- Understanding the physicochemical properties of these enzymes is essential for characterizing their function and structure.
Purpose of the Study:
- To determine the physicochemical parameters of glycyl-L-leucine hydrolase and aminoacyl-L-proline hydrolase from pig small intestine.
- To elucidate the subunit composition and molecular shape of these two dipeptidases.
Main Methods:
- Purification of glycyl-L-leucine hydrolase and aminoacyl-L-proline hydrolase.
- Sedimentation equilibrium ultracentrifugation to determine native and denatured molecular weights.
- Gel chromatography to analyze Stokes radius.
- Viscometry and sedimentation velocity to determine sedimentation coefficients and intrinsic viscosities.
Main Results:
- Native molecular weights of 115,000 and 113,000 Da were determined for glycyl-L-leucine hydrolase and aminoacyl-L-proline hydrolase, respectively.
- Denatured molecular weights of 51,000 and 63,200 Da indicated dimeric structures for both enzymes.
- Both dipeptidases shared a Stokes radius of 4.2 nm and exhibited characteristics consistent with prolate ellipsoids of revolution with an axial ratio of approximately 5.
Conclusions:
- Glycyl-L-leucine hydrolase and aminoacyl-L-proline hydrolase from pig small intestine are composed of two subunits of roughly equal molecular weight.
- The determined physicochemical parameters support a prolate ellipsoidal model for the overall molecular structure of both dipeptidases.