Marek Cieplak
Polish Academy of Sciences, Poland
Title: Structural changes in proteins at fluid-fluid interfaces
Biography
Biography: Marek Cieplak
Abstract
We study the behavior of several proteins at the air–water and oil–water interfaces by all-atom molecular dynamics. Th e
proteins are found to change orientation and get distorted when pinned to the interface. Th is behavior is consistent with
the empirical way of introducing the interfaces in a coarse-grained model through a hydropathy related force. Proteins couple
to the oil-water interface stronger than to the air-water one. Th ey diff use slower at the oil-water interface but do not depin from
it, whereas depinning events are observed at the other interface. Th e reduction of the disulfi de bonds slows the diff usion down.
We use the model to study interfacial protein layers and demonstrate existence of glassy eff ects as evidenced by slowing down of
diff usion with increasing concentration of proteins. We also show that layers of two barley proteins, LTP1 and its ligand adduct
LTP1b, fl atten out at the interface and can make a continuous and dense fi lm that should be responsible for formation and stability
of foam in beer. Th e degree of the fl attening depends on the protein - the layers of LTP1b should be denser than those of LTP1 – as
well as on the presence of glycation and on the number of disulfi de bonds.