Isolation of immunoglobulin molecules that lack inter-heavy chain disulfide bonds
First Claim
1. A method for separating IgG half antibodies from IgG whole antibodies, wherein the half antibodies and the whole antibodies are of the same isotype, comprising:
- obtaining a sample that contains a mixture of IgG half antibodies and IgG whole antibodies of the same isotype;
reducing the pH of the sample such that the half antibodies dissociate from one another to form a resulting solution; and
applying the resulting solution to a column that differentially retards the mobility of the IgG half antibodies and IgG whole antibodies.
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Abstract
The current invention features methods for reliably and controllably separating immunoglobulin half antibodies from immunoglobulin whole antibodies, as well as purified immunoglobulin half antibody preparations and purified immunoglobulin whole antibody preparations while preserving biological activity. These dissociated half antibodies can be chromatographically separated from whole antibodies. There are four known subclasses of IgG molecules: IgG1; IgG2; IgG3; and IgG4. IgG4 molecules differ from the other IgG isotypes in that the disulfide bonds that link the two heavy chain subunits together do not always form. Due to the non-covalent interactions that hold the heavy chain subunits together, the heterogeneity of IgG4 molecules is not apparent following gel filtration of purified IgG4 protein. However, when purified IgG4 protein is separated by denaturing polyacrylamide gel electrophoresis (SDS-PAGE) under non-reducing conditions, two distinct protein species can be identified—whole antibody and “half-antibodies.”
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Citations
62 Claims
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1. A method for separating IgG half antibodies from IgG whole antibodies, wherein the half antibodies and the whole antibodies are of the same isotype, comprising:
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obtaining a sample that contains a mixture of IgG half antibodies and IgG whole antibodies of the same isotype;
reducing the pH of the sample such that the half antibodies dissociate from one another to form a resulting solution; and
applying the resulting solution to a column that differentially retards the mobility of the IgG half antibodies and IgG whole antibodies. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 57, 59, 60, 61)
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31. A method for separating IgG half antibodies from IgG whole antibodies, wherein the half antibodies and the whole antibodies are of the same isotype, comprising:
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obtaining a sample that contains a mixture of IgG half antibodies and IgG whole antibodies of the same isotype;
reducing the pH of the sample such that the half antibodies dissociate from one another to form a resulting solution;
applying the resulting solution to an ion exchange column such that both the IgG half antibodies and IgG whole antibodies are retained by the column;
adding a buffer to the column such that the pH of the buffer present within the column increases to a level sufficient to selectively elute the IgG half antibodies; and
subsequently adding a buffer to the column such that the ionic strength of the buffer present within the column increases to an amount sufficient to elute the IgG whole antibodies. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 58, 62)
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54. A purified IgG half antibody preparation, wherein at least 90% of the total antibodies in the preparation are half antibodies.
- 55. A purified IgG whole antibody preparation, wherein the preparation includes half antibodies and whole antibodies and wherein at least 80% of the total antibodies are whole antibodies.
Specification