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Mouse submaxillary gland renin. Purification and properties of minor forms, which include several differently
Abstract:
Three minor forms of renin from the submaxillary glands of male mice called D1, D2, and E have been purified to homogeneity. Their amino acid compositions are identical to the principal form of mouse submaxillary gland renin (renin A), except for 1, 1, and 2 extra arginine residues, respectively. The electrophoretic mobility of renin D2 does not change upon reduction, indicating that its heavy and light chains are linked by more than a disulfide bond. The light chain of renin D1 has an electrophoretic mobility different from the light chain of renin A. Renin D2 is proposed to be renin A with an arginine-arginine dipeptide connecting the carboxyl terminus of the heavy chain to the NH2 terminus of the light chain, with the light chain missing the carboxyl-terminal arginine of renin A. Renin D1 is suggested to be renin D2 with the peptide bond between an arginine and the NH2 terminus of the light chain cleaved. Renin E is proposed to be renin D1 plus the carboxyl-terminal arginine of the light chain. A fourth minor form of male mouse submaxillary renin, called renin B/A, has been purified to homogeneity in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and in isoelectric focusing. Renin B/A seems to be a second renin gene product which is difficult to separate from renin A. Renin B/A has an amino acid composition significantly different from renin A, and all three preparations of B/A had compositions significantly different from one another. For renin B/A, the light chain sequence and the first 53 NH2-terminal residues of its heavy chain sequence were identical to renin A.
Insights
Researchers purified minor forms of mouse submaxillary gland renin (D1, D2, E) and identified unique structural differences, including extra arginine residues and altered chain linkages, providing insights into renin heterogeneity.
Area of Science:
- Biochemistry
- Proteomics
- Enzymology
Background:
- Mouse submaxillary gland renin exists in multiple forms.
- Understanding renin heterogeneity is crucial for its functional characterization.
Purpose of the Study:
- To purify and characterize minor forms of mouse submaxillary gland renin (D1, D2, E, B/A).
- To elucidate the structural basis for the heterogeneity among these renin forms.
Main Methods:
- Purification of renin forms to homogeneity.
- Amino acid composition analysis.
- Electrophoresis (including reduction studies) and isoelectric focusing.
- Peptide sequencing of light and heavy chains.
Main Results:
- Three minor renin forms (D1, D2, E) share identical amino acid composition with renin A, differing only by 1-2 extra arginine residues.
- Renin D2 exhibits unique inter-chain linkage, suggesting a novel structural modification.
- Renin D1 and E represent sequential modifications of renin D2.
- A fourth form, renin B/A, appears to be a distinct gene product with significant compositional differences from renin A, though sharing sequence identity in parts of its chains.
Conclusions:
- Mouse submaxillary gland renin exhibits significant structural heterogeneity.
- Minor renin forms arise from post-translational modifications, including variations in arginine content and inter-chain disulfide bonds.
- Renin B/A represents a separate renin gene product, distinct from the modified forms of renin A.