Sample Preparation using ProSpectrum Libraries™

One of the major impediments to the discovery of new biomarkers and therapeutic proteins is the vast range of protein concentrations in critical samples such as whole blood. The signal from abundant proteins such as albumin, present at 40 mg/ml, block the signal of trace proteins, which could be present at concentrations of 1 ng/ml or less, a difference in concentration of 10 orders of magnitude. Prolias has developed methods to overcome this concentration range issue, without specifically depleting any proteins.

ProSpectrum Libraries (PSL-2) can be used for proteomic sample preparation from a number of complex biological materials, including anti-coagulated whole blood. In any library there is a fixed number of ligands with sufficient specificity and affinity to any particular protein to bind it without interference from more abundant proteins. If the library has, say, 1000 beads with a total binding capacity of 1 ug of albumin, these ligands will quickly be saturated with 1 µg of the 40 mg albumin in 1 ml of plasma, and the vast majority of the albumin will remain in the unbound fraction. If the library has the same number of appropriate ligands to a trace protein, however, it will bind the majority of a protein present at 1 ng/ml. When the bound proteins are eluted, the eluted material will contain 1 µg of albumin and 1 ng of trace protein- a difference of 3 orders of magnitude, when in the original sample the albumin was present at 40 mg/ml versus 1 ng/ml- a difference of 7 orders of magnitude.

1. Whole blood before contact showing abundant proteins
2. Unbound whole blood proteins after treatment with ProSpectrum Libraries™
3. Whole blood proteins bound to ProSpectrum Libraries™
• Compare proteins detectable in lanes 1 and 3
4. Molecular weight markers.
5. Plasma before contact showing abundant proteins
6. Unbound plasma proteins after contact with ProSpectrum Libraries™
7. Plasma proteins bound to ProSpectrum Libraries™
• Compare proteins detectable to lane 5 and 7