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The article discusses research on the crystal form structure in a human methemoglobin that indicates fiber formation. Experimental procedures include an array of crystallization to reproducibly grow crystals with the use of vapor diffusion in Cryschem plates. It was shown that the Mu-Magdoff-Fairchild result is pertinent with the demonstration of the classical HbS filaments transforming to yield fiber diffraction pattern but it did not offer an explanation on the occurrence of fiber transformation.

Bovine pancreatic ribonuclease A (RNase A) was crystallized from a mixture of small molecules containing basic fuchsin, tobramycin and uridine 5′-monophosphate (U5P). Solution of the crystal structure revealed that the enzyme was selectively bound to U5P, with the pyrimidine ring of U5P residing in the pyrimidine-binding site at Thr45. The structure was refined to an R factor of 0.197 and an Rfree of 0.253. [ABSTRACT FROM AUTHOR]

Pig heart citrate synthase was crystallized from a small-molecule cocktail containing cystamine dihydrochloride, aspartame and benzamidine hydrochloride. The structure was refined to an R factor of 0.179 ( Rfree = 0.222) using synchrotron data to a resolution of 1.78 Å. The model includes the full-length protein, a chloride ion, a sulfate ion, 305 water molecules and an unexpected moiety attached through a disulfide linkage to Cys184, which was modeled as a half-cystamine molecule generated by disulfide exchange with the cystamine in the small-molecule cocktail. [ABSTRACT FROM AUTHOR]

Proteinase K, a subtilisin-like fungal protease, was crystallized from a cocktail of small molecules containing digalacturonic acid (DGA). The crystal structure was determined to 1.32 Å resolution and refined to an R factor of 0.158. The final model contained, beside the protein, two calcium ions, 379 water molecules, a molecule of DGA and a partially occupied HEPES molecule. The DGA molecule has one sugar moiety disposed exactly on a crystallographic twofold axis; the second ring was not observed. The DGA molecule is bound to two protein molecules across the twofold axis through hydrogen-bonding networks involving Ser150 and water molecules. One of the calcium-ion sites has not been reported previously. This study further illustrates the involvement of small molecules in the crystallization of macromolecules through their ability to form intermolecular lattice interactions. [ABSTRACT FROM AUTHOR]