Geometric control of vimentin intermediate filaments.

Significant efforts have addressed the role of vimentin intermediate filaments (VIF) in cell motility, shape, adhesion and their connections to microfilaments (MF) and microtubules (MT). The present work uses micropatterned substrates to control the shapes of mouse fibroblasts and demonstrates that the cytoskeletal elements are dependent on each other and that unlike MF, VIF are globally controlled. For example, both square and circle shaped cells have a similar VIF distribution while MF distributions in these two shapes are quite different and depend on the curvature of the shape.

The uses of supramolecular chemistry in synthetic methodology development: examples of anion and neutral molecular recognition.

The principles of supramolecular chemistry have successfully permeated through a broad range of organic chemistry subdisciplines. One subdiscipline that is not routinely associated with supramolecular chemistry is that of organic synthetic methodology. Though sometimes indiscernible, non-bonded and bonding supramolecular interactions play a large role in chemical reactions and catalysis.

Pattern-based recognition for the rapid determination of identity, concentration, and enantiomeric excess of subtly different threo diols.

A pattern-based recognition approach for the rapid determination of the identity, concentration, and enantiomeric excess of chiral vicinal diols, specifically threo diols, has been developed. A diverse enantioselective sensor array was generated using three chiral boronic acid receptors and three pH indicators. The optical response produced by the sensor array was analyzed by two pattern-recognition algorithms: principal component analysis and artificial neural networks.

Guidelines for pattern recognition using differential receptors and indicator displacement assays.

A colorimetric sensor array consisting of designed receptors and metal salts was utilized for discrimination of structurally similar carboxylic acid analytes (25-31). For the discrimination, the receptors do not need to have a 1:1 guest-receptor binding stoichiometry. More than 1:1 stoichiometry, such as 1:2 or 2:1, affords useful information for the discrimination.

Probing intramolecular B-N interactions in ortho-aminomethyl arylboronic acids.

This work investigates the interplay between the intramolecular B-N dative bonding and solvent insertion in various ortho-methylamino arylboronic acids in protic media. (11)B NMR experiments were conducted to study the effect that the degree of substitution of the amine group has on B-N bonding versus solvent insertion. It was found that there is a slight increase in the amount of B-N dative bonding on going from a tertiary to a secondary to a primary amine group, but that solvent insertion dominates in all cases of the boronate esters.

Molecular recognition and self-assembly special feature: A general protocol for creating high-throughput screening assays for reaction yield and enantiomeric excess applied to hydrobenzoin.

A general approach to high-throughput screening of enantiomeric excess (ee) and concentration was developed by using indicator displacement assays (IDAs), and the protocol was then applied to the vicinal diol hydrobenzoin. The method involves the sequential utilization of what we define herein as screening, training, and analysis plates. Several enantioselective boronic acid-based receptors were screened by using 96-well plates, both for their ability to discriminate the enantiomers of hydrobenzoin and to find their optimal pairing with indicators resulting in the largest optical responses.

Chromogenic cross-linker for the characterization of protein structure by infrared multiphoton dissociation mass spectrometry.

We have developed a new IR chromogenic cross-linker (IRCX) to aid in rapidly distinguishing cross-linked peptides from unmodified species in complex mixtures. By incorporating a phosphate functional group into the cross-linker, one can take advantage of its unique IR absorption properties, affording selective infrared multiphoton dissociation (IRMPD) of the cross-linked peptides. In a mock mixture of unmodified peptides and IRCX-cross-linked peptides (intramolecularly and intermolecularly cross-linked), only the peptides containing the IRCX modification were shown to dissociate upon exposure to 50 ms of 10.

Sequencing and characterization of oligosaccharides using infrared multiphoton dissociation and boronic acid derivatization in a quadrupole ion trap.

A simplified method for determining the sequence and branching of oligosaccharides using infrared multiphoton dissociation (IRMPD) in a quadrupole ion trap (QIT) is described. An IR-active boronic acid (IRABA) reagent is used to derivatize the oligosaccharides before IRMPD analysis. The IRABA ligand is designed to both enhance the efficiency of the derivatization reaction and to facilitate the photon absorption process.

Two methods for the determination of enantiomeric excess and concentration of a chiral sample with a single spectroscopic measurement.

The previously established enantioselective indicator-displacement assays (eIDAs) for the determination of concentration and enantiomeric excess (ee) require two spectroscopic measurements for each chiral sample. To further simplify the operation of eIDAs, we now introduce two innovative analytical methods, both of which utilize a dual-chamber quartz cuvette, which reduces the number of spectroscopic measurements from two to one. An attractive feature of this cuvette is that the concentration- and ee-dependent absorption data can be collected at the isosbestic points or transparent regions of the spectra recorded in each individual chamber, thereby reflecting optical changes that occur in the other chamber.

A structural investigation of the N-B interaction in an o-(N,N-dialkylaminomethyl)arylboronate system.

o-(Pyrrolidinylmethyl)phenylboronic acid (4) and its complexes with bifunctional substrates such as catechol, alpha-hydroxyisobutyric acid, and hydrobenzoin have been studied in detail by X-ray crystallography, (11)B NMR, and computational analysis. The N-B interactions in analogous boronic acids and esters have been extensively cited in molecular recognition and chemosensing literature. The focal point of this study was to determine the factors that are pertinent to the formation of an intramolecular N-B dative bond.