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New Techniques Developed to Bind Peptides, Proteins

Qing Lin (Univ. at Buffalo)

Qing Lin (Univ. at Buffalo)

Research chemists at University at Buffalo in New York have devised two new ways of binding peptides to helix-shaped proteins, making the peptides more resistant to enzymes and more valuable in therapies. One of those binding techniques, called photoclick stapling, is described in a paper published online last month in the journal Bioorganic and Medicinal Chemistry Letters (paid subscription required).

Stapled peptides contribute to therapies by binding tightly to target proteins inside cells. This close bond disrupts specific protein-to-protein interactions that regulate many biological processes, including response to stress, signaling within cells, and cell death. Stapling peptide helices prevents these molecules from losing their shape and degrading in the presence of enzymes.

According to Buffalo chemistry professor Qing Lin (pictured right), who led the research, keeping that helix shape is important for the peptides to do their job. Peptides, which are short strings of amino acids, shift between different shapes, including a helix, sheet, and random coil. Stapling the peptides’ side chains encourages the peptides to adopt and stay in a helix, which enables them to enter cells more easily. Thus keeping to that helix shape makes it more difficult for enzymes to break down the peptides.

Other methods for stapling peptides exist, notably a process using a ruthenium catalyst to connect chemical side chains that protrude from the main body of helical peptides. Ruthenium, however, is in growing demand for electronics and industrial chemicals, and in the past 12 months its price has fluctuated between $175 and $245 an ounce.

Lin says the methods his team developed are simpler, more efficient, and less expensive than using ruthenium. The photoclick stapling technique — the one described in the journal publication last month — uses ultraviolet light to develop synthetic peptides. Under ultraviolet light, the two side chains of carbon and nitrogen compounds form chemical bonds with one another.

The second stapling technique devised by Lin and his colleagues synthesizes peptides carrying two amino acids called cysteines that contain sulfur in their side chains. When scientists expose these peptides to a chemical that reacts selectively with the sulfur atoms, the reacting chemical staples the two cysteine side chains.

Stapled peptides are believed to have potential for creating a new class of therapies to treat a wide variety of health problems, including cancer and inflammatory, metabolic, and infectious diseases. Buffalo’s technology transfer office is applying for patents to cover both stapling methods.

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