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Mass Spec Standard FAQs
1. Q: What are the heavy labeled amino acids used for the production of MS standard proteins?
A: They are L-Arginine: HCL (U-13C6; U-15N4) and L-Lysine: 2HCL (U-13C6; U-15N2).
2. Q: For HEK293T cells, how many doublings were passed in heavy amino acid containing medium?
A: The HEK293T cells were grown in heavy isotope supplemented medium for at least 10 doubling times to ensure complete incorporation of heavy labeled amino acids.
3. Q: What kind of protein expression system does OriGene use for the production of heavy labeled MS standard proteins?
A: OriGene expresses and purifies from only mammalian cells and we primarily use HEK293T cells, a line derived from human embryonic kidney. The production cells have been incorporated with heavy labeled L-Arginine and L-Lysine through SILAC approach
4. Q: What is the OriGene guarantee for the purified MS standard proteins?
A: OriGene guarantees that the purified MS standard proteins will show at least 80% purity by SDS-PAGE/Coomassie staining, will exhibit at least over 90% incorporation efficiency for heavy labeled isotopic amino acids, will contain <0.1EU/ug of endotoxin, will be fully soluble at a minimum concentration of 50ug/ml, and will not contain any detectable protease, DNase, or RNase activity
5. Q: Where can I find the concentration of the purified protein that I received?
A: The concentration of the purified protein is determined by BCA assay (Pierce) and is on the tube and the Certificate of Analysis.
6. Q: The MS standard size offered is 10µg and this is not enough for my assays. Can I order a larger amount?
A: Yes, you can contact OriGene technical support team to inquire large quantity service.
7. Q: What is the stability of OriGene’s purified MS standard protein?
A: OriGene guarantees that the protein will remain stable for up to three months after receipt pending appropriate storage and handling.
8. Q: What are the recommended storage and handling conditions for MS standard protein samples?
A: Store at –80C. Thaw on ice, aliquot to individual single-use tubes, and then re-freeze immediately. Only 2-3 freeze thaw cycles are recommended.
9. Q: What buffer is the protein provided in?
A: The final buffer composition is:100mM glycine, 24mM Tris-HCl, pH 7.3.
10. Q: What method does OriGene use to purify the MS standard proteins?
A: All proteins are purified using our standard anti-DDK immunoaffinity column.