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Structural and charge interaction analyses of the binding site of the aspartate 95 mutants of the Desulfovibrio vulgaris flavodoxin reveals the role played by the hydrogen bonding in the modulation of the redox potentials of the bound flavodoxin, particularly the carboxylate group of the mutant.

Researchers describe the structural changes that occur as the lipase from Thermomyces lanuginosa is activated in the presence of lipids. During this process the enzyme exists in a low activity form, an activated form, and a fully active form.

NMR structure determination and molecular dynamics simulations are performed to understand the critical interactions between subunits B and F in the [A.sub.1][A.sub.O] ATP synthase of Methanosarcina mazei [G.sup.0]1. Movements of both helices of [B.sub.Mm] are observed to accommodate the incoming C-terminus of [F.sub.Mm] and connect the events of ion pumping and nucleotide binding in the [A.sub.1][A.sub.O] ATP synthase.

The studies of papain, the member of the cysteine proteinase superfamily are carried out to demonstrate the role of noncovalent interactions in enzyme active center chemistry. The findings provide insight into the generation of substantial nucleophilic reactivity in the (Cys25)-[S.sup.-]/(His159)-[Im.sup.+]H ion pair by decreasing the level of mutual solvation of the anionic and cationic partners.

The solution studies and crystal structure analysis of N-lithocholyl insulin, in which residue Lys(super B29) has been acylated with a bile acid derivative, are presented. The unit cell in the crystal consists of an insulin hexamer containing two zinc ions, which have two m-cresol molecules, bound at each dimer-dimer interface stabilizing an R6 conformation.

The addition of a phenol to a hexameric insulin solution leads to the formation of a stable hexamer whose stability arises from a rearrangement in which residues B1-B8 form an (alpha)-helix in the R-state. This R-state, in turn, is partly stabilized by the nonpolar interactions between the phenolic molecule and residue B5 His at the dimer-dimer surface. To test if a tyrosine side chain could mimic the effect of phenol binding and induce the R-state, a B5 His -> Tyr mutant human insulin was constructed. The results showed that it could not since the mutation destabilized the T-state.