Computer-assembled cross-species/cross-modalities two-pore physiologically based pharmacokinetic model for biologics in mice and rats.

Two-pore physiologically-based pharmacokinetic (PBPK) models can be expected to describe the tissue distribution and elimination kinetics of soluble proteins, endogenous or dosed, as function of their size. In this work, we amalgamated our previous two-pore PBPK model for an inert domain antibody (dAb) in mice with the cross-species platform PBPK model for monoclonal antibodies described in literature into a unified two-pore platform that describes protein modalities of different sizes and includes neonatal Fc receptor (FcRn) mediated recycling. This unified PBPK model was parametrized for organ-specific lymph flow rates and the endosomal recycling rate constant using an extended tissue distribution time-course dataset that included an inert dAb, albumin and IgG in rats and mice.

[P3Se4](+): A Binary Phosphorus-Selenium Cation.

Although a fairly large number of binary group 15/16 element cations have been reported, no example involving phosphorus in combination with a group 16 element has been synthesized and characterized to date. In this contribution is reported the synthesis and structural characterization of the first example of such a cation, namely a nortricyclane-type [P3Se4](+). This cation has been independently discovered by three groups through three different synthetic routes, as described herein.

Isolatable organophosphorus(III)-tellurium heterocycles.

A new structural arrangement Te3 (RP(III) )3 and the first crystal structures of organophosphorus(III)-tellurium heterocycles are presented. The heterocycles can be stabilized and structurally characterized by the appropriate choice of substituents in Tem (P(III) R)n (m=1: n=2, R=OMes* (Mes*=supermesityl or 2,4,6-tri-tert-butylphenyl); n=3, R=adamantyl (Ad); n=4, R=ferrocene (Fc); m=n=3: R=trityl (Trt), Mesor by the installation of a P(V) 2 N2 anchor in RP(III) [TeP(V) (tBuN)(μ-NtBu)]2 (R=Ad, tBu).

Quality of Cell Products: Authenticity, Identity, Genomic Stability and Status of Differentiation.

Cellular therapies that either use modifications of a patient's own cells or allogeneic cell lines are becoming in vogue. Besides the technical issues of optimal isolation, cultivation and modification, quality control of the generated cellular products are increasingly being considered to be more important. This is not only relevant for the cell's therapeutic application but also for cell science in general.

Structural and NMR spectroscopic investigations of chair and twist conformers of the P2Se8(2-) anion.

Four new salts of the P2Se8(2-) anion have been prepared, starting from easily available reagents using different reaction strategies including reaction of the elements, oxidation of P4Se3 with alkalimetal diselenides and elemental selenium, and the use of an ionic liquid as a reaction medium. Multinuclear NMR investigations show the presence of both chair-P2Se8(2-) and twist-P2Se8(2-) in solution, with twist-P2Se8(2-) being the predominant conformer. The interconversion between the two conformers is slow on the NMR time scale.

Aggregation-resistant domain antibodies selected on phage by heat denaturation.

We describe a method for selecting aggregation-resistant proteins by heat denaturation. This is illustrated with antibody heavy chain variable domains (dAbs), which are prone to aggregate. The dAbs were displayed multivalently at the infective tip of filamentous bacteriophage, and heated transiently to induce unfolding and to promote aggregation of the dAbs.

Crystal structure of HEL4, a soluble, refoldable human V(H) single domain with a germ-line scaffold.

The antigen binding site of antibodies usually comprises associated heavy (V(H)) and light (V(L)) chain variable domains, but in camels and llamas, the binding site frequently comprises the heavy chain variable domain only (referred to as V(HH)). In contrast to reported human V(H) domains, V(HH) domains are well expressed from bacteria and yeast, are readily purified in soluble form and refold reversibly after heat-denaturation. These desirable properties have been attributed to highly conserved substitutions of the hydrophobic residues of V(H) domains, which normally interact with complementary V(L) domains.

Binding of p53-derived ligands to MDM2 induces a variety of long range conformational changes.

We have used NMR to study the effects of peptide binding on the N-terminal p53-binding domain of human MDM2 (residues 25-109). There were changes in HSQC-chemical shifts throughout the domain on binding four different p53-derived peptide ligands that were significantly large to be indicative of global conformational changes. Large changes in chemical shift were observed in two main regions: the peptide-binding cleft that directly binds the p53 ligands; and the hinge regions connecting the beta-sheet and alpha-helical structures that form the binding cleft.

Cooperative organization in a macromolecular complex.

The mechanism of assembly of multiprotein complexes and the subsequent organization of activity are not well understood. Here we report the application of biophysical tools to investigate the relationship between structure and function in protein assemblies. We used as a model system the SCF(Skp2) complex that targets p27(Kip1) for ubiquitination and subsequent degradation; this process requires an adapter protein, Cks1.

Molecular mechanism of the interaction between MDM2 and p53.

We have investigated the kinetic and thermodynamic basis of the p53-MDM2 interaction using a set of peptides based on residues 15-29 of p53. Wild-type p53 peptide bound MDM2 with a dissociation constant of 580nM. Phosphorylation of S15 and S20 did not affect binding, but T18 phosphorylation weakened binding tenfold, indicating that phosphorylation of only T18 is responsible for abrogating p53-MDM2 binding.

The structure of an FF domain from human HYPA/FBP11.

The FF domain is a 60 amino acid residue phosphopeptide-binding module found in a variety of eukaryotic proteins including the transcription elongation factor CA150, the splicing factor Prp40 and p190RHOGAP. We have determined the structure of an FF domain from HYPA/FBP11. The domain is composed of three alpha helices arranged in an orthogonal bundle with a 3(10) helix in the loop between the second and third alpha helices.