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Articles 1 - 14 of 14
Full-Text Articles in Physical Sciences and Mathematics
Using Lectinmicroarrays To Identify Regulatory Mechanisms For Mammalian Glycosylation, John F. Rakus
Using Lectinmicroarrays To Identify Regulatory Mechanisms For Mammalian Glycosylation, John F. Rakus
Chemistry Faculty Research
Glycosylation involves the post-translational addition of carbohydrates to protein molecules and is an intricate and indispensable biochemical process. Study of this complicated network of interactions is hindered by the lack of a coding template analogous to the genetic code, and by the vast structural complexity inherent to carbohydrate polymers. We use lectins (non-enzymatic carbohydrate-binding proteins of non-immunological origin) as microarray probes to identify carbohydrate features expressed on cellular surfaces. Specifically, we utilized lectin microarray technology to investigate the differences in carbohydrates expressed by the cell lines of the Nation Cancer Institute’s NCI-60 panel. Our investigation identified tissue-specific expression differences in …
Nanomolar Binding Of Peptides Containing Noncanonical Amino Acids By A Synthetic Receptor, Leigh A. Logsdon, Christopher L. Schardon, Vijayakumar Ramalingam, Sharon K. Kwee, Adam R. Urbach
Nanomolar Binding Of Peptides Containing Noncanonical Amino Acids By A Synthetic Receptor, Leigh A. Logsdon, Christopher L. Schardon, Vijayakumar Ramalingam, Sharon K. Kwee, Adam R. Urbach
Chemistry Faculty Research
This paper describes the molecular recognition of phenylalanine derivatives and their peptides by the synthetic receptor cucurbit[7]uril (Q7). The 4-tert-butyl and 4-aminomethyl derivatives of phenylalanine (tBuPhe and AMPhe) were identified from a screen to have 20–30-fold higher affinity than phenylalanine for Q7. Placement of these residues at the N-terminus of model tripeptides (X-Gly-Gly), resulted in no change in affinity for tBuPhe-Gly-Gly, but a remarkable 500-fold increase in affinity for AMPhe-Gly-Gly, which bound to Q7 with an equilibrium dissociation constant (Kd) value of 0.95 nM in neutral phosphate buffer. Structure–activity studies revealed that three functional groups …
Cucurbit[8]Uril Rotaxanes, Vijayakumar Ramalingam, Adam R. Urbach
Cucurbit[8]Uril Rotaxanes, Vijayakumar Ramalingam, Adam R. Urbach
Chemistry Faculty Research
The synthesis of [2]rotaxanes, each comprising a viologen core threaded through a cucurbit[8]uril (Q8, Figure 1) macrocycle and stoppered by tetraphenylmethane groups, and their binding to second guests as inclusion complexes in organic and aqueous media are described. Stoppering was observed to have little effect on binding. Chemical modification of the threaded guest was used to control solubility and binding characteristics, thus demonstrating a novel approach to making artificial receptors with readily modifiable properties.
An Integrated Systems Approach To Deconstructing Glycosylation, L. K. Mahal, John F. Rakus, Kanoelani Pilobello, P. Agrawal
An Integrated Systems Approach To Deconstructing Glycosylation, L. K. Mahal, John F. Rakus, Kanoelani Pilobello, P. Agrawal
Chemistry Faculty Research
Glycosylation involves the post-translational addition of carbohydrates to protein molecules and is an intricate and indispensable biochemical process. Study of this complicated network of interactions is hindered by the lack of a coding template analogous to the genetic code, and by the vast structural complexity inherent to carbohydrate polymers. We use lectins (non-enzymatic carbohydrate-binding proteins of non-immunological origin) as microarray probes to identify carbohydrate features expressed on cellular surfaces. Specifically, we utilized lectin microarray technology to investigate the differences in carbohydrates expressed by the cell lines of the Nation Cancer Institute’s NCI-60 panel. Our investigation identified tissue-specific expression differences in …
A Systems Approach To Understanding The Role Of Glycans In Cancer, John F. Rakus, Kaneolani T. Pilobello, Laura K. Mahal
A Systems Approach To Understanding The Role Of Glycans In Cancer, John F. Rakus, Kaneolani T. Pilobello, Laura K. Mahal
Chemistry Faculty Research
Glycosylation involves the post-translational addition of carbohydrates to protein molecules and is an intricate and indispensable biochemical process. Study of this complicated network of interactions is hindered by the lack of a coding template analogous to the genetic code, and by the vast structural complexity inherent to carbohydrate polymers. We use lectins (non-enzymatic carbohydrate-binding proteins of non-immunological origin) as microarray probes to identify carbohydrate features expressed on cellular surfaces. Specifically, we utilized lectin microarray technology to investigate the differences in carbohydrates expressed by the cell lines of the Nation Cancer Institute’s NCI-60 panel. Our investigation identified tissue-specific expression differences in …
Molecular Recognition Of Insulin By A Synthetic Receptor, Jordan M. Chinai, Alexander B. Taylor, Lisa M. Ryno, Nicholas D. Hargreaves, Christopher A. Morris, P John Hart, Adam R. Urbach
Molecular Recognition Of Insulin By A Synthetic Receptor, Jordan M. Chinai, Alexander B. Taylor, Lisa M. Ryno, Nicholas D. Hargreaves, Christopher A. Morris, P John Hart, Adam R. Urbach
Chemistry Faculty Research
The discovery of molecules that bind tightly and selectively to desired proteins continues to drive innovation at the interface of chemistry and biology. This paper describes the binding of human insulin by the synthetic receptor cucurbit[7]uril (Q7) in vitro. Isothermal titration calorimetry and fluorescence spectroscopy experiments show that Q7 binds to insulin with an equilibrium association constant of 1.5 × 106 M−1 and with 50−100-fold selectivity versus proteins that are much larger but lack an N-terminal aromatic residue, and with >1000-fold selectivity versus an insulin variant lacking the N-terminal phenylalanine (Phe) residue. The crystal structure of the …
Determining Protease Substrate Selectivity And Inhibition By Label-Free Supramolecular Tandem Enzyme Assays, Garima Ghale, Vijayakumar Ramalingam, Adam R. Urbach, Werner M. Nau
Determining Protease Substrate Selectivity And Inhibition By Label-Free Supramolecular Tandem Enzyme Assays, Garima Ghale, Vijayakumar Ramalingam, Adam R. Urbach, Werner M. Nau
Chemistry Faculty Research
An analytical method has been developed for the continuous monitoring of protease activity on unlabeled peptides in real time by fluorescence spectroscopy. The assay is enabled by a reporter pair comprising the macrocycle cucurbit[7]uril (CB7) and the fluorescent dye acridine orange (AO). CB7 functions by selectively recognizing N-terminal phenylalanine residues as they are produced during the enzymatic cleavage of enkephalin-type peptides by the metalloendopeptidase thermolysin. The substrate peptides (e.g., Thr-Gly-Ala-Phe-Met-NH2) bind to CB7 with moderately high affinity (K ≈ 104 M–1), while their cleavage products (e.g., Phe-Met-NH2) bind very tightly (K …
Molecular Recognition Of Amino Acids, Peptides, And Proteins By Cucurbit[N]Uril Receptors, Adam R. Urbach, Vijayakumar Ramalingam
Molecular Recognition Of Amino Acids, Peptides, And Proteins By Cucurbit[N]Uril Receptors, Adam R. Urbach, Vijayakumar Ramalingam
Chemistry Faculty Research
At the forefront of the endeavor to understand and manipulate living systems is the design and study of receptors that bind with high affinity and selectivity to specific amino acids, peptides, and proteins. Cucurbit[n]urils are among the most promising class of synthetic receptors for these targets due to their high affinities and selectivities in aqueous media and to the unique combination of electrostatic and hydrophobic interactions that govern binding. The fundamental supramolecular chemistry in this area has been explored in depth, and novel, useful applications are beginning to emerge.
Polymorphs And Hydrates Of Acyclovir, Katie M. Lutker, Rosalynn Quiñones-Fernández, Jiadi Xu, Ayyalusamy Ramamoorthy, Adam J. Matzger
Polymorphs And Hydrates Of Acyclovir, Katie M. Lutker, Rosalynn Quiñones-Fernández, Jiadi Xu, Ayyalusamy Ramamoorthy, Adam J. Matzger
Chemistry Faculty Research
Acyclovir (ACV) has been commonly used as an antiviral for decades. Although the crystal structure of the commercial form, a 3:2 ACV/water solvate, has been known since 1980s, investigation into the structure of anhydrous ACV has been limited. Here, we report the characterization of four anhydrous forms of ACV and a new hydrate in addition to the known hydrate. Two of the anhydrous forms appear as small needles and are stable to air exposure, whereas the third form is morphologically similar but quickly absorbs water from the atmosphere and converts back to the commercial form. The high-temperature modification is achieved …
Dications Of 3-Phenyl-Indenylidene Dibenzo[ A.D ]Cycloheptene: The Role Of Charge In The Antiaromaticity Of Cationic Systems, Nancy S. Mills, Francine E. Cheng, Joseph M. Baylan, Cornelia Tirla, Jennifer L. Hartmann, Kiran C. Patel, Bart J. Dahl, Sean P. Mcclintock
Dications Of 3-Phenyl-Indenylidene Dibenzo[ A.D ]Cycloheptene: The Role Of Charge In The Antiaromaticity Of Cationic Systems, Nancy S. Mills, Francine E. Cheng, Joseph M. Baylan, Cornelia Tirla, Jennifer L. Hartmann, Kiran C. Patel, Bart J. Dahl, Sean P. Mcclintock
Chemistry Faculty Research
Dications of 9-(3-phenyl-1H-inden-1-ylidene)-5H-dibenzo[a,d]cycloheptene, 52+, were prepared by oxidation with SbF5 in SO2ClF, and their magnetic behavior was compared to dications of 9-(3-phenyl-1H-inden-1-ylidene)-9H-fluorene, 22+. The good correlation between the experimental 1H NMR shifts for the dications that were oxidized cleanly and the chemical shifts calculated by the GAIO method supported the use of the nucleus independent chemical shifts, NICS, to evaluate the antiaromaticity of the indenyl systems of 22+/52+ and their unsubstituted parent compounds, 62+ and 72+, as well as the antiaromaticity of the fluorenyl system of 22+/72+ …
Dications Of Benzylidenefluorene And Diphenylmethylidene Fluorene: The Relationship Between Magnetic And Energetic Measures Of Antiaromaticity, Catherine Do, Julianne Hatfield, Shirali Patel, D Vasudevan, Cornelia Tirla, Nancy S. Mills
Dications Of Benzylidenefluorene And Diphenylmethylidene Fluorene: The Relationship Between Magnetic And Energetic Measures Of Antiaromaticity, Catherine Do, Julianne Hatfield, Shirali Patel, D Vasudevan, Cornelia Tirla, Nancy S. Mills
Chemistry Faculty Research
Oxidation of m- and p-substituted benzylidene fluorenes to antiaromatic dications was attempted by electrochemical and chemical means. Electrochemical oxidation to dications was successful for benzylidene fluorenes with p-methoxy, p-methyl, p-fluoro, and unsubstituted phenyl rings in the 3-position; attempts to oxidize the m-substituted derivatives via electrochemistry were unsuccessful. Chemical oxidation with SbF5/SO2ClF gave the dication of 9-[(4-methoxyphenyl)methylene]-9H-fluorene cleanly; oxidation of all other substituted benzylidene fluorenes resulted in mixtures of products. The excellent linear relationship between the chemical shifts calculated by the GIAO method and the experimental shifts for the p-methoxy-substituted benzylidene fluorene dication …
Access To Nmr Spectroscopy For Two-Year College Students: The Nmr Site At Trinity University, Nancy S. Mills, M. Shanklin
Access To Nmr Spectroscopy For Two-Year College Students: The Nmr Site At Trinity University, Nancy S. Mills, M. Shanklin
Chemistry Faculty Research
Students at two-year colleges and small four-year colleges have often obtained their exposure to NMR spectroscopy through "canned" spectra because the cost of an NMR spectrometer, particularly a high-field spectrometer, is prohibitive in these environments. This article describes the design of a NMR site at Trinity University in which spectral data from student samples from community colleges and several four-year colleges are obtained on a 300 MHz NMR spectrometer. The unprocessed free induction decay (FID) is distributed to the students via the Internet and then processed by the students at their local institutions. The success of the NMR site at …
Antiaromatic Dianions: Dianions Of Dixanthylidene By Reduction And Attempted Excited-State Deprotonation, Mary Black, Clifford Woodford, Nancy S. Mills
Antiaromatic Dianions: Dianions Of Dixanthylidene By Reduction And Attempted Excited-State Deprotonation, Mary Black, Clifford Woodford, Nancy S. Mills
Chemistry Faculty Research
Reduction of dixanthylidene with potassium or lithium resulted in formation of the antiaromatic dianion in high yield. Attempts to form the dianion by excited-state deprotonation of dixanthene with n-butyllithium/TMEDA resulted in formation of the tetraanion from deprotonation ortho to the oxygen. Orientation of the sp3 hydrogens presumably allows preferential deprotonation of the xanthene rings.
Reduction Of Benzylidene Dibenzo[ A, D ]Cycloheptenes: Over-Reduction Of Antiaromatic Dianions To Aromatic Tetraanions, Blakely Tresca, Macdonald Higbee, Nancy S. Mills
Reduction Of Benzylidene Dibenzo[ A, D ]Cycloheptenes: Over-Reduction Of Antiaromatic Dianions To Aromatic Tetraanions, Blakely Tresca, Macdonald Higbee, Nancy S. Mills
Chemistry Faculty Research
The antiaromaticity of a series of dianions of p-substituted benzylidene dibenzo[a,d]cycloheptenes was examined through calculated measures of antiaromaticity. The nucleus-independent chemical shifts (NICS) and magnetic susceptibility exaltation both showed substantial antiaromatic character in the benzannulated tropylium anion. When the antiaromaticity was normalized for the area of the ring, these tropylium anions were shown to be among the most antiaromatic anions in the chemical literature. Attempts to make the dianion through reduction with lithium or potassium gave the tetraanion as the only species observable in the (1)H NMR spectrum. Quench of the reaction mixture with trimethylsilyl chloride or D(2)O confirmed the …