Author ORCID Identifier

Document Type


Date of Award

Spring 4-26-2024


photo-crosslinking, peptides, membranes, lipids, tryptophan, cysteine

Degree Name

Biochemistry (BS)



First Advisor

Ming An, PhD

Second Advisor

Lan Yao, PhD


Science and Mathematics

Subject Heading(s)

Tryptophan--antagonists & inhibitors ; Tryptophan--analysis ; Membrane Lipids--metabolism


Our research group has previously discovered that a Cys residue within a transmembrane (TM) helix can directly photo-crosslink to a membrane lipid via an oxythiolation addition reaction to the double bond within the lipid, with a reaction yield of 10-20%. The pH-low Insertion Peptide (pHLIP) serves as our model TM helix, while the POPC lipid bilayer is our model membrane. We had long believed that the Trp residues within the sequence of pHLIP served as the key chromophore for this reaction, and thus they were essential for the formation of the TM helix-lipid adduct. To test this hypothesis, I synthesized a negative control pHLIP variant (i.e., W9Y-W15Y-L16C-pHLIP) in which each of the Trp residues was replaced by a Tyr residue. Interestingly, my recent experiments have challenged the need for Trp in this reaction. W9Y-W15Y-L16C-pHLIP has been reproducibly shown to photo-crosslink to POPC in higher-than-expected yields of 2-9%, suggesting the possibility of there being an alternative reaction pathway. Each cross-linking reaction was monitored with HPLC. The HPLC-purified peptide-lipid adduct was characterized and quantified using UV-visible spectroscopy and LC-MS.

Included in

Biochemistry Commons