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Researcher in membrane structural biology. Murakami and collaborators determined multidrug-transporter structures supporting a functionally rotating mechanism, connecting different molecular conformations with stages of a transport cycle.^[ref]

Researcher in computational structural biology. Scheres developed RELION, connecting Bayesian inference with reconstruction of molecular structures from cryo-electron microscopy images.^[ref]

Researcher in structural biology. Long and collaborators determined the architecture of a mammalian voltage-dependent potassium channel, connecting the positions of pore and voltage-sensing components with the mechanism of electrical activation.^[ref]

Stewart Shuman is a biochemist who investigates how enzymes modify and repair nucleic acids. His laboratory combines biochemistry, structural biology and genetics to connect a particular chemical reaction with the protein machinery that performs it.^[ref]

With Anupam K. Chakravarty, Shuman tested competing reaction mechanisms for the RNA ligase RtcB. The question concerned the chemistry of the broken RNA ends: did a cyclic phosphate join directly to an opposing hydroxyl end, or did opening and activation precede sealing? Their 2012 experiments supported a GTP-dependent pathway involving hydrolysis, activated reaction intermediates and formation of a new phosphodiester bond.^[ref]

The logical force of such an experiment can be seen without assuming that a successful final reaction reveals every step. Suppose mechanisms A and B both predict a joined RNA molecule, but A requires GTP even when the starting end already contains a cyclic phosphate, whereas B predicts that this substrate bypasses the GTP requirement. Comparing otherwise equivalent reactions with and without GTP distinguishes those predictions. Detecting an intermediate also requires attention to chemical kinetics: a species appearing only after product accumulation cannot explain an earlier obligatory step. These are general reasons to combine selective changes in starting chemistry with time-resolved measurements, rather than identifying a reaction mechanism solely from the final product.

A structural biologist studies the three-dimensional organization of biological macromolecules and how it relates to their function. Structural biology combines measurement with a macromolecular structural model: a representation supported by experimental observations, rather than a direct photograph of every atom. Common approaches include X-ray crystallography, cryo-electron microscopy and NMR spectroscopy.

In X-ray crystallography, a crystal produces a diffraction pattern from which researchers infer an electron density map and refine a molecular model. A concrete dataset is calmodulin structure1CLL in the Protein Data Bank. Its primary record reports X-ray diffraction at $1.70\mathring{\mathrm{A}}$ resolution and a refined model containing four calcium ions.^[ref]

An original unit conversion gives the scale:That resolution value is not a universal error bar of $0.170\mathrm{nm}$ on every modeled atom. Some regions can be well constrained while flexible or disordered regions are poorly resolved. In1CLL, the primary paper's abstract explicitly identifies poorly defined terminal residues.^[ref]

A structural biologist can then test a mechanistic proposal with complementary evidence. A model may suggest a calcium ion binding environment; comparing binding or activity measurements can test its functional consequences. A static arrangement alone does not establish every reaction step or rate. The scientific work lies in connecting the model, its uncertainty and the behavior of the molecular system.

Researcher in structural biology. Nakane and collaborators demonstrated single-particle cryo-electron microscopy at atomic resolution, connecting instrumental and analytical improvements with more detailed molecular interpretation.^[ref]

Researcher in membrane structural biology. Eicher and collaborators investigated access and deep binding pockets in AcrB, connecting a moving protein loop with the route taken by transported drugs.^[ref]

Researcher in structural biology. Kawashima and collaborators determined the structure of the EF-Tu–EF-Ts complex, connecting interactions between translation factors with the molecular mechanism of nucleotide exchange.^[ref]