Recombinant Intrinsic Factor



Recombinant Intrinsic Factor - Purified | View Recombinant Intrinsic Factor Data (as PDF)

Recombinant Human Intrinsic Factor (IF) from Scripps Laboratories is offered as a high-quality replacement for native porcine IF. The quality of the native porcine IF available to the clinical diagnostic industry has declined in recent years, so Scripps Laboratories developed a highly purified recombinant IF that is a reliable and economical alternative to native IF. Data are presented here to demonstrate the suitability of Recombinant Human Intrinsic Factor for research use or Vitamin B12 assay development.



Figure 1 presents an SDS-PAGE image of highly purified Recombinant Human IF, Mat. No. I0821-90658. It displays an approximate molecular weight greater than 40kDa and less than 50 kDa. This is consistent with the reported molecular weight of 44-48 kDA for Native Human IF.1 In addition, the purified product shows no visible contaminating proteins, both in the reduced/heated (lanes 1,2) and non-reduced/not heated (lanes 6,7) samples.





Recombinant Human IF is a glycosylated protein, so we employed Isoelectric Focusing to visualize the heterogeneity of the glycosylation patterns. Figure 2 shows a variety of distinct isoelectric points, ranging from 4.75 to 6.3, demonstrating the microheterogeneity of this purified, glycosylated protein. The Recombinant Human IF sample was run in duplicate.





Recombinant Human IF and Native Porcine IF were conjugated to biotin and each conjugate was used side-by-side as a component of a Vitamin B12 ELISA.2

Figure 3 shows the generation of standard curves, using the Vitamin B12 standards included with the ELISA kit. The top graph was prepared using the Recombinant Human IF-Biotin conjugate, while the bottom graph was prepared with the Native Porcine IF-Biotin conjugate. (Note: The Native Porcine IF-Biotin used is the reagent included with the ELISA kit.) The charts demonstrate good correlation, indicating Recombinant Human IF-Biotin is suitable for use in generating a standard curve in ELISA.




Figure 4 presents a scatter plot showing good correlation when Recombinant Human IF-Biotin is substituted for Native Porcine IF-Biotin in the Vitamin B12 ELISA. The data represent the recoveries of a series of 36 Vitamin B12 samples with both biotin conjugates. With an R-squared (R2) value of 0.9979, the linear regression shows a strong positive correlation between Recombinant Human IF and Native Porcine IF.




Of note, Recombinant Human IF-Biotin demonstrated good thermal stability after storage at 37°C for 2 weeks.



Analyzed by HPLC, the elution profile of Recombinant Human IF in Figure 5 displays a single peak with an elution time of 17.092. The absence of any minor peaks confirms what is corroborated by SDS-PAGE: Recombinant Human IF is a highly purified product with no discernible contaminants.




The data presented here for Recombinant Human IF demonstrate it possesses the physical characteristics and Vitamin B12-binding capabilities to make it a suitable replacement for Native Porcine IF in a Vitamin B12 assay. It is a highly purified, glycosylated protein and, as a renewable recombinant product, it is ideal for research work as well as long-term use in the development and production of a commercial assay.

Recombinant Human Intrinsic Factor is in stock and available now:

Recombinant Intrinsic Factor


(1) Allen and Mehlman. J. Biol. Chem., 1973, (248): 3660.

(2) Vitamin B12 ELISA data generated by Calbiotech - El Cajon, CA USA.