Infrared techniques for quantifying protein structural stability.

Biopharmaceutical and biotechnology companies and regulatory agencies require novel methods to determine the structural stabilities of proteins and the integrity of protein-protein, protein-ligand, and protein-membrane interactions that can be applied to a variety of sample states and environments. Infrared spectroscopy is a favorable method for a number of reasons: it is adequately sensitive to minimal sample amounts and is not limited by the molecular weight of the sample; yields spectra that are simple to evaluate; does not require protein modifications, a special supporting matrix, or internal standard; and is applicable to soluble and membrane proteins. In this paper, we investigate the application of infrared spectroscopy to the quantification of protein structural stability by measuring the extent of amide hydrogen/deuterium exchange in buffers containing D(2)O for proteins in solution and interacting with ligands and lipid membranes.

Speciation of the catalytic oxygen evolution system: [MnIII/IV2(mu-O)2(terpy)2(H2O)2](NO3)3 + HSO5-.

[MnIII/IV2(-O)2(terpy)2(OH2)2](NO3)3 (1, where terpy = 2,2':6'2' '-terpyridine) + oxone (2KHSO5 x KHSO4 x K2SO4) provides a functional model system for the oxygen-evolving complex of photosystem II that is based on a structurally relevant Mn-(-O)2-Mn moiety (Limburg, J.; et al. J.

Lyophilization cycle development for a high-concentration monoclonal antibody formulation lacking a crystalline bulking agent.

An efficient freeze-dry cycle was developed for a high concentration monoclonal antibody formulation lacking a crystalline bulking agent. The formulation, at multiple protein concentrations, was characterized using differential scanning calorimetry (DSC) and freeze-dry microscopy. At low protein concentrations the glass transition temperature of the maximally freeze-concentrated solution (T(g)') determined by DSC was similar to the collapse temperature determined by freeze-dry microscopy.

Raman spectra and normal coordinate analyses of low-frequency vibrations of oxo-bridged manganese complexes.

The active sites of certain metalloenzymes involved in oxygen metabolism, such as manganese catalase and the oxygen-evolving complex of photosystem II, contain micro -oxo-bridged Mn clusters with ligands that include H(2)O and micro (1,3)-carboxylato bridges provided by protein side chains. In order to understand better the vibrational spectra of such clusters, the low-frequency resonance Raman spectra of a series of structurally characterized Mn-oxo model complexes were examined. The series includes complexes of the type [Mn(2)(O)(OAc)(2)(bpy)(2)(L)(2)] and [Mn(2)(O)(2)(OAc)(bpy)(2)(L)(2)], where bpy=2,2'-bipyridine, OAc=acetate and L=H(2)O or Cl(-).

Water oxidation chemistry of photosystem II.

The O(2)-evolving complex of photosystem II catalyses the light-driven four-electron oxidation of water to dioxygen in photosynthesis. In this article, the steps leading to photosynthetic O(2) evolution are discussed. Emphasis is given to the proton-coupled electron-transfer steps involved in oxidation of the manganese cluster by oxidized tyrosine Z (Y(*)(Z)), the function of Ca(2+) and the mechanism by which water is activated for formation of an O-O bond.