The penta­phenyl­cyclo­penta­dienyl iron alkyl and aryl com­plexes [(C₅Ph₅)Fe(CO)₂R] (R = Me, Ph, iPr and Bu) were prepared and their crystal structures examined.

A 1.8 Å resolution structure of the sphingolipid activator protein saposin A has been determined at pH 4.8, the physiologically relevant lysosomal pH for hydrolase enzyme activation and lipid-transfer activity.

Four crystal structures of human coronavirus NL63 main protease (M^pro) in the apo form at different pH values are reported at resolutions of up to 1.78 Å. Comparison with M^pro from other human betacoronaviruses such as SARS-CoV-2 and SARS-CoV reveals common and distinct structural features in the different genera and extends knowledge of the diversity, function and evolution of coronaviruses.

Iodination of Ph₂Te₂Se by mol­ecular iodine is directed towards the Te atom and yields PhTeSeTeI₂Ph. The mol­ecule can be considered as a chimera of PhTeSeR, PhTeSeTePh and R′TeI₂Ph fragments. The energies of the inter­molecular inter­actions have been calculated and analyzed.

Structures of orthorhombic crystals of lysozyme at pH 4.5 show that the binding of phosphate ions produces long-range conformational changes and that low humidity produces a displacement of the fifth α-helix towards the active-site cavity. The interaction of some anions must be considered when analysing experiments with lysozyme at acidic pH values.

The structure of the putative membrane-binding tandem PX-PH domain module of the yeast protein Bem3 is reported.

The aspartic protease from N. gracilis was crystallized in complex with the inhibitor pepstatin A using a newly formulated low-pH screen. X-ray diffraction data showed that the crystals diffracted to 2.8 Å resolution.

Reaction of BI₃ with carbodi­phospho­rane, C(PPh₃)₂, gives a mixture of the dicationic compounds, [Ph₃PCH₂PPh₃]I₂·2CH₂Cl₂ and [Ph₃PCH₂PPh₃](BI₄)₂. Solvents are the source of the protons at the ylidic C atom.

The complexation of Am(III) with acetate as a function of the pH value is investigated by EXAFS spectroscopy. EXAFS measurements are combined with thermodynamic speciation calculations and iterative transformation factor analysis.

Bovine β-lactoglobulin was crystallized at pH 3.8 from 3 M NaCl in a unique crystal form with apparent P6₃22 symmetry. The hexagonal prismatic crystal in fact belonged to space group C222₁, a subgroup of P6₃22, with three molecules in the asymmetric unit and exhibited an unusual type of twinning. The structure was solved by molecular replacement and refined to an R factor of 0.23.