Biophysical Society Conference | Tahoe 2023

Proton Reactions: From Basic Science to Biomedical Applications

Monday Speaker Abstracts

NEW INSIGHTS ON PROTON TRANSPORT IN BIOSYSTEMS USING A LIGHT TRIGGERED PROTON DONOR AND SOLID-STATE PROTONIC DEVICES Nadav Amdursky 1 ; 1 Technion - Israel Institute of Technology, Chemistry, Haifa, Israel Proton transport (PT) in biology is of prime importance and involves primarily PT circuits within proteins, whereas PT on the surface of membranes also has a significant role in biological PT circuits. In this talk, I will introduce two new approaches that we developed resulting in fundamental new insights into PT properties in proteins and membranes. The first method is based on the introduction of a light-triggered proton donor to the biosystem. This proton donor is a photoacid that can release a proton (deprotonate) only in its excited-state. The most important challenge here is to locate the proton donor at a specific location within the biosystem. For this, we have synthetically modified the photoacid in two ways: 1) Creating a lipophilic photoacid, enabling its selective placement on the surface of biological membranes; 2) Making unnatural photoacid and photobase amino acids, enabling the insert of a proton donor (photoacid) and acceptor (photobase) within specific locations in peptides. Using ultrafast spectroscopy, we can extract the kinetic of the PT, and resolve the role of the biosystem in this process. The second method is solid-state protonic devices, meaning measuring proton conductance across the biosystem. This approach allows the decoupling/investigation of the role of water in PT by controlling the amount of adsorbed water molecules by adjusting the relative humidity. Using our new methodologies, we were able to decipher several important factors associated with PT on the surface of biological membranes and across peptides. We have found that the phospholipid headgroup is of prime importance in dictating lateral PT. Also, the membrane fluidity and phase were found to be very important for supporting PT. For peptides, we found that the structure of the peptide can dictate its capability to support PT and also the importance of some amino acids in supporting the PT process.

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