Site-specific conjugation of diethylenetriaminepentaacetic acid to recombinant human granulocyte-colony-stimulating factor: preservation of protein structure and function
| Autor: | Scott L. Lauren, Lloyd D. Ralph, Charles M. Ransone, Viswanatham Katta, Michael J. Treuheit, David C. Litzinger |
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| Rok vydání: | 1995 |
| Předmět: |
Circular dichroism
Protein Folding Biochemistry High-performance liquid chromatography Peptide Mapping Mass Spectrometry Protein Structure Secondary law.invention law Cricetinae Granulocyte Colony-Stimulating Factor Animals Humans Chelation Protein secondary structure Chromatography Binding Sites Isoelectric focusing Chemistry Circular Dichroism Hydrogen-Ion Concentration Pentetic Acid Recombinant Proteins Yield (chemistry) Immunology Recombinant DNA Conjugate |
| Zdroj: | Biochemistry. 34(14) |
| ISSN: | 0006-2960 |
| Popis: | The chelating agent diethylenetriaminepentaacetic acid (DTPA) was conjugated site-specifically to the N-terminus of recombinant human granulocyte-colony-stimulating factor (rhG-CSF) by reaction of the protein with DTPA dianhydride at an initial pH of 6.0. The reaction was efficient in that 84% of the starting rhG-CSF was N-terminally modified and could be purified to homogeneity by cation-exchange chromatography. Chelation of 111In by the DTPA-rhG-CSF conjugate was demonstrated by cation-exchange HPLC and thin-layer chromatography. Metal contamination of conjugate preparations, as well as metal-loading onto the conjugate, could be monitored by either cation-exchange HPLC or isoelectric focusing. The 1:1 stoichiometric molar ratio of DTPA to protein for the DTPA-rhG-CSF conjugate was determined by thin-layer chromatography and mass spectrometry, and the localization of the conjugated DTPA moiety was resolved using a peptide mapping procedure. The secondary structure (i.e., alpha-helicity) of the protein was unmodified following conjugation as revealed by circular dichroism. Furthermore, the conjugate induced a similar induction of peripheral WBC counts as unmodified rhG-CSF when injected subcutaneously into hamsters, demonstrating preservation of protein bioactivity. These results reveal a simple and efficient method for conjugating DTPA to protein, via reaction with the dianhydride, to yield a homogeneous and well-defined product. The procedure may prove to be a useful method of labeling growth factors and related proteins while preserving structural and functional integrity. |
| Databáze: | OpenAIRE |
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