Structural and Biophysical Characterization of a Cyclic Bioadhesive with Cell Attachment Ability

Structural and cellular attachment analysis identified overall bent helical regions of adhesive peptides identified within mussel adhesive protein (MAP) capable of also attaching cells. DOPA (L-DOPA, 3,4-dihydroxyphenylalanine) is frequently identified and credited for the attachment ability of several marine proteins. Newly designed cyclic peptides (DOPA-G-G-C-G-K-A-K-G-C [cyc-DOPA] & Y-G-G-C-G-K-A-K-G-C [cyc-Y]) derived from structurally conserved regions of several MAP peptides were examined to assist in the understanding of both surface and cellular attachment. Solution-state proton nuclear magnetic resonance (NMR) spectroscopy coupled with molecular modeling and dynamics revealed minimal differences in the structures of the proposed cellular attachment domain within these two peptides. Multiple attenuated internal reflection infrared (MAIR-IR) spectroscopy, ellipsometry, and advancing contact angle analyses showed that formation of thin films by these peptides was L-DOPA- and pH-dependent. When compared with control surfaces, undifferentiated leukocyte cells (MOLT-4) significantly attached and spread onto films created from the cyc-DOPA. The culmination of these structural, biophysical, and cellular attachment techniques reveal a conformation of cyc-DOPA that is capable of both adsorbing to surfaces and then attaching cells that spread. This work supports the sequence K-A-K as the cellular attachment domain, especially when held in a reliable structural conformation.