The spike protein responsible for COVID-19 infection is like a loaded spring, with a catch, according to new research. The findings, based on simulations of the process by which the spike reconfigures itself to attach to and infect cells, may help researchers find new ways to defeat the SARS-CoV-2 virus. The catch comes in the form of glycans, sugar molecules that are attached to the “head” domain of the spike and enclose it while the fusion peptide “tails” go in search of a cell to invade. The cage formed by these steric (nonbinding but influential) glycans hold the head domain in check, giving the fusion peptides time to look around. Once the virus finds a host, the head and viral membrane are pulled toward the tail, fusing with the unfortunate cell. “The glycans give the fusion peptides enough time to diffuse,” says co-principal investigator José Onuchic, co-director of the Rice University-based …