Background
Protein D is a 42 kDa surface-exposed lipoprotein from Haemophilus influenzae that is conserved among H. influenzae strains. It is highly immunogenic and its ability to stimulate T-cell immunity with a low risk of interference from simultaneously administered vaccines makes it a strong carrier protein candidate. The 10-valent pneumonoccal conjugate vaccine PHiD-CV licensed in 2008 (Synflorix, GSK Vaccines) uses protein D in 8 out of 10 pneumonoccal serotypes.
Scarab Genomics’ Protein D is a recombinant form expressed in Clean Genome® E. coli, our proprietary platform.
SOURCEClean Genome® E. coli expressed recombinant Protein D
PRODUCT MOLECULAR MASS:42 kiloDaltons
Figures
Scarab Genomics’ Protein D is exceptionally pure. Five replicates of Scarab’s Protein D were run on a Bis-Tris 4-12% gradient SDS polyacrylamide gel and stained with GelCode™ Blue, then purity assessed via gel scan. Average purity was 96.5%.
The sequence of Scarab Protein D was confirmed by amino acid sequencing and mass spectrometry (MS).Bioinformatics analysis of MS material revealed no post-translational modifications. Amino acid sequencing identified pure Protein D and found no norleucine incorporation. MS coverage was 92% (blue letters).
Protein D was stable for one month in storage buffer at -20oC (day 0 in each case), 4oC and 23oC. By 30 days, a slight decrease in Protein D band intensity was evident after incubation at 37oC. 
Scarab’s Protein D is conjugation efficient Protein D lot 1 (PDlot1) and PDlot2 were almost as efficient in lysine conjugation as the carrier protein CRM197 and the control, BSA. Using Solulink’s ChromaLink™ Biotin conjugation assay, which uses a NHS ester reaction scheme to conjugate Biotin to primary amines (absorbance at 354 nm), we found at least 5 sites on Scarab’s Protein D that were accessible for conjugation. Far more of the 36 lysines in Protein D are likely accessible for conjugation but excessive attachment of ChromaLink Biotin causes conjugated proteins to be insoluble.
Specifications
Quality Control
| Purity: |
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| Concentration: | 1 mg/mL in 25mM triethanolamine, 150mM NaCl, pH7.4 via absorbance at 280 nm using an E0.1%=1.58 for a 1 mg/mL solution |
| Endotoxin: | 35 EU/mg of protein by the kinetic turbidimetric LAL method (maximum sensitivity = 0.01 EU/mL) |
Grade: Protein D is for Research Use Only, Not for use in humans or as a diagnostic agent.
Storage Conditions:
- Protein D is a 0.2 µm-filtered frozen solution of 1 mg/mL Protein D, 150mM NaCl, 25mM triethanolamine, pH 7.4. Store at -70°C upon receipt.
- Repeated freeze-thaw cycles can degrade material. To minimize freeze-thaw cycles, aliquot Protein D to match desired use.
- Handle product gently, DO NOT VORTEX.
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Patents & Disclaimers
Scarab is providing you with this Material subject to the non-transferable right to use the subject amount of the Material for your research at your academic institution. The Recipient agrees not to sell or otherwise transfer this Material, or anything derived or produced from the Material to a third party. NO RIGHTS ARE PROVIDED TO USE THE MATERIAL OR ANYTHING DERIVED OR PRODUCED FROM THE MATERIAL FOR COMMERCIAL PURPOSES. If the Recipient makes any changes to the chromosome of the Material that results in an invention in breach of this limited license, then Scarab will have a worldwide, exclusive, royalty-free license to such invention whether patentable or not. If the Recipient is not willing to accept the terms of this limited license, Scarab is willing to accept return of this product with a full refund, minus shipping and handling costs. For information on obtaining a license to this Material for purposes other than research, please contact Scarab’s Licensing Department. Scarab Genomics’ technology is covered by the following Patent Applications: US, 15/122,891, PCT/US2016/25588 and their related foreign applications.Clean Genome® is a registered trademark of Scarab Genomics, LLC.
