Antibody Biomarker Discovery Via In Vitro Evolution of Peptides.

Antigen discovery and mapping strategies that enable the precise identification of serum antibody-binding epitopes in human diseases will be invaluable for translational diagnostics and therapeutic development. Protein and peptide library display screening techniques have shown utility for the discovery of antigens associated with disease onset and progression. Here, we describe a screening methodology using bacterial peptide library display to identify consensus families of disease-specific binding motifs to multiple pools of human serum antibodies. The sensitivity and specificity of identified disease-specific peptide motifs are then optimized using in vitro evolution techniques.

Halogenated DOPA in a Marine Adhesive Protein.

The sandcastle worm Phragmatopoma californica, a marine polychaete, constructs a tube-like shelter by cementing together sand grains using a glue secreted from the building organ in its thorax. The glue is a mixture of post-translationally modified proteins, notably the cement proteins Pc-1 and Pc-2 with the amino acid, 3,4-dihydroxyphenyl-L-alanine (DOPA). Significant amounts of a halogenated derivative of DOPA were isolated from the worm cement following partial acid hydrolysis and capture of catecholic amino acids by phenylboronate affinity chromatography. Analysis by tandem mass spectrometry and (1)H NMR indicates the DOPA derivative to be 2-chloro-4, 5-dihydroxyphenyl-L-alanine. The potential roles of 2-chloro-DOPA in chemical defense and underwater adhesion are considered.