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Lei Jin coauthored structural research on how heparin activates the inhibitory protein antithrombin. A 1997 paper compared crystallographic structures involving active and latent antithrombin and its high-affinity five-sugar binding sequence at 2.9-ångström resolution.^[ref]

The study linked binding to changes in the main beta sheet and exposure of the reactive-center loop, providing a structural account of how a carbohydrate ligand changes the behaviour of a serpin.^[ref] The point is more informative than simply observing that heparin and antithrombin bind: the locations of structural changes suggest how binding can alter access to the inhibitory machinery.

A structure is a constrained molecular snapshot. Establishing a complete time sequence or the rate of inhibition requires additional kinetic evidence; it cannot be read directly from a static arrangement of atoms.

By Lei Jin and colleagues. PNAS94(26),14683–14688(23December1997). DOI doi.org/10.1073/pnas.94.26.14683

Abstract: 2.9-angstrom structures of latent/active antithrombin with the high-affinity pentasaccharide; conformational changes involving the main beta-sheet and reactive-center loop.