10/14/2025
Don't miss this opportunity to attend an encore presentation of Dr. Michael Gelb's impactful MSACL 2025 presentation! Join Wednesday, October 29 at 10am Pacific. Register for the join link: www.msacl.org/connect
Moderated by Andy Hoofnagle.
Talk Summary:
Targeted proteomics using complex biological fluids usually requires enrichment of signature peptides prior to tandem mass spectrometry. Anti-peptide antibodies are useful in this context but can be difficult to obtain in a timely fashion. We have recently developed a computational design platform that yields proteins capable of binding targeted peptides with high affinity (nanomolar to picomolar range). When applied to 30 targeted peptides, high affinity binders were obtained in 28 cases.
In this talk we will illustrate the method for newborn screening and diagnosis of a rare lysosomal storage disease called cystinosis. Patients with this disease are deficient in a lysosomal cystine transporter. Trypsinization of proteins extracted from a 3 mm punch of a dried blood spot are treated with the designed peptide binder. After peptide capture and release, the signature peptide for the cystine transporter is readily detected by LC-MS/MS. Most cystinosis patients show a large decrease in the abundance of this target peptide.
We also developed a peptide methylation scheme whereby peptides are methylated on amino groups by treatment with formaldehyde and sodium cyanoborohydride. Using heavy isotope forms of formaldehyde, we can combine 4 patient samples into a single LC-MS/MS run and thus decrease the time per sample by 4-fold. This method can be multiplexed to measure the abundance of several proteins in a single analysis. We will show data for Wilson disease and a panel of primary immunodeficiencies.
