Hydroxocobalamin association during cell culture results in pink therapeutic proteins.

Process control of protein therapeutic manufacturing is central to ensuring the product is both safe and efficacious for patients. In this work, we investigate the cause of pink color variability in development lots of monoclonal antibody (mAb) and Fc-fusion proteins. Results show pink-colored product generated during manufacturing is due to association of hydroxocobalamin (OH-Cbl), a form of vitamin B12.

Crystallization and liquid-liquid phase separation of monoclonal antibodies and fc-fusion proteins: screening results.

Crystallization holds the potential to be used for protein purification and low-viscosity drug substance and drug product formulations. Twenty-two different proteins (20 monoclonal antibodies and two Fc-fusions) were examined to determine the breadth of applicability of crystallization to these therapeutic proteins. Vapor diffusion technique and an evaporative screening method were used to identify crystallization conditions using around a 100 initial conditions based on reagents that are generally regarded as safe (GRAS).

Ligand close packing, molecular compactness, the methyl tilt, molecular conformations, and a new model for the anomeric effect.

All the atoms in a molecule attract each other until they reach their equilibrium positions at which point the repulsive forces between the atoms just balance the attractive forces and there are no resultant forces acting on any of the atoms in the molecule. Thus, we can consider that in the equilibrium geometry the atoms in a molecule are arranged as compactly as possible. This is the basis of the ligand close packing (LCP) model according to which three or four monatomic ligands X, such as F, Cl or O (formally =O or O(-)) pack as closely as possible around a small central atom such as a boron or carbon atom giving a truly close-packed equilateral triangular AX(3) molecule or a tetrahedral AX(4) molecules.

Recent advancement in application of hydrophobic interaction chromatography for aggregate removal in industrial purification process.

Hydrophobic interaction chromatography (HIC) is a classic purification tool applied in protein and antibody, laboratory and industrial production process. It has been mainly used for the removal of both product-related impurities such as aggregates, as well as process contaminants such as host cell proteins. This review will focus on the recent development of HIC in its applications in the industrial purification processes.

A topological study of the geometry of AF6E molecules: weak and inactive lone pairs.

The geometries of AF6E molecules, which may have either an O(h) or a C(3v) geometry, have been studied by means of the electron localization function. Our results show that when the molecule has a C(3v) geometry, there is a valence-shell monosynaptic V(A) basin corresponding to the presence of a lone pair in the valence shell of the central atom A. The population of this basin is, however, extensively delocalized so that the electron density has a core-valence basin character, which is consistent with an earlier suggestion of a weakly active lone pair that gives a C(3v) distorted octahedral molecule rather than the valence-shell electron-pair repulsion predicted pentagonal-pyramid geometry.

Models of molecular geometry.

Although the structure of almost any molecule can now be obtained by ab initio calculations chemists still look for simple answers to the question "What determines the geometry of a given molecule?" For this purpose they make use of various models such as the VSEPR model and qualitative quantum mechanical models such as those based on the valence bond theory. The present state of such models, and the support for them provided by recently developed methods for analyzing calculated electron densities, are reviewed and discussed in this tutorial review.

An electron localization function study of the geometry of d(0) molecules of the period 4 metals Ca to Mn.

We have studied the geometry of the formally d(0) MX(n)() (X = F, H, CH(3) and O; n = 2-6) molecules of the period 4 metals from Ca to Mn by studying the topology of the electron localization function (ELF) in order to try to understand why many of these molecules have non-VSEPR geometries. The quantitative analysis of the core basin population shows that it is always larger than its conventional value (18) because, in the LCAO-MO scheme, the 3d basis functions centered on the metal noticeably contribute to the electron density within the core region associated with the M shell. Therefore, the density available to form the bonds is less than Z(M) - 18, the value adopted in electron counts.

Chemical bonding in hypervalent molecules: is the octet rule relevant?

The bonding in a large number of hypervalent molecules of P, As, S, Se, Te, Cl, and Br with the ligands F, Cl, O, CH(3), and CH(2) has been studied using the topological analysis of the electron localization function ELF. This function partitions the electron density of a molecule into core and valence basins and further classifies valence basins according to the number of core basins with which they have a contact. The number and geometry of these basins is generally in accord with the VSEPR model.

Ligand Close-Packing and the Lewis Acidity of BF(3) and BCl(3).

The unexpected greater Lewis acidity of BCl(3) than BF(3) with respect to strong bases such as NH(3) has been the subject of much discussion. A number of explanations have been proposed, among which the most popular and most widely quoted is that stronger back-donation from fluorine than from chlorine decreases the availability of the otherwise empty 2p orbital on boron from accepting an electron pair from a base. In contrast, toward weak bases such as CO, BF(3) is a stronger Lewis acid than BCl(3).

Bonding and Geometry of OCF(3)(-), ONF(3), and Related Molecules in Terms of the Ligand Close Packing Model.

The nature of the bonding in OCF(3)(-) and the isoelectronic molecule ONF(3) has been the subject of much discussion for many years, because these species appear to have unusual bond lengths and angles. We have reinvestigated the nature of the bonding in these and some related molecules by analyzing their calculated electron density distributions. The results show that the bonding in the series OBF(3)(2)(-), OCF(3)(-), ONF(3) ranges from predominately ionic in OBF(3)(2)(-) to predominately covalent in ONF(3) and that the interligand distances are consistent with the close packing of the ligands around the central atom.

Bond Lengths and Bond Angles in Oxo, Hydroxo, and Alkoxo Molecules of Be, B, and C: A Close-Packed Nearly Ionic Model.

We have surveyed the experimental data for oxo, hydroxo, and alkoxo molecules of Be, B, and C and have shown that the intramolecular interligand distances for a given central atom are remarkably constant and independent of coordination number and of the presence of other ligands. Atomic charges obtained from the analysis of the calculated electron densities for a large selection of molecules of this type have shown that these molecules are predominately ionic. On the basis of these results we suggest that the bond lengths and geometries of these molecules can be best understood in terms of a model in which anion-like ligands are close-packed around a cation-like central atom.

Study of Bond Angles and Bond Lengths in Disiloxane and Related Molecules in Terms of the Topology of the Electron Density and Its Laplacian.

We have calculated the electron density distributions for the series of molecules H(n)XOXH(n), X = Li to F and Na to Cl, and some related molecules. We have analyzed these distributions and their Laplacian to obtain atomic charges, electron densities at the bond critical point, and the charge concentrations revealed by the Laplacian. On the basis of this information and an analysis of the X-O bond lengths and angles, we have examined the factors that determine the lengths of the X-O bonds and the XOX bond angles.

Reinterpretation of the Lengths of Bonds to Fluorine in Terms of an Almost Ionic Model.

We have calculated the electron density distributions, electron densities at the bond critical point, and atomic charges in the period 2 and 3 fluorides and a number of their cations and anions. On the basis of this information and an analysis of X-F bond lengths, we have examined the factors that determine the lengths of these bonds. We have shown that all the molecules except NF(3), OF(2), and F(2) have considerable ionic character.

Geometry of the Fluorides, Oxofluorides, Hydrides, and Methanides of Vanadium(V), Chromium(VI), and Molybdenum(VI): Understanding the Geometry of Non-VSEPR Molecules in Terms of Core Distortion.

This paper describes a study of the topology of the electron density and its Laplacian for the molecules VF(5), VMe(5), VH(5), CrF(6), CrMe(6), CrOF(4), MoOF(4), CrO(2)F(2,) CrO(2)F(4)(2)(-) and CrOF(5)(-) all of which, except VF(5,) CrF(6), and CrOF(5)(-) have a non-VSEPR geometry. It is shown that in each case the interaction of the ligands with the metal atom core causes it to distort to a nonspherical shape. In particular, the Laplacian of the electron density reveals the formation of local concentrations of electron density in the outer shell of the core, which have a definite geometrical arrangement such as four in a tetrahedral arrangement or five in a square pyramidal or trigonal bipyramidal and six in an octahedral arrangement.