A5013854268- Chemical Synthesis and Analysis
- Carbohydrate Chemistry and Synthesis
- Synthetic Organic Chemistry Methods
- Microbial Natural Products and Biosynthesis
- Click Chemistry and Applications
- Asymmetric Synthesis and Catalysis
- Cyclization and Aryne Chemistry
- Chemical Synthesis and Reactions
- Catalytic Alkyne Reactions
- Analytical Chemistry and Chromatography
- Asymmetric Hydrogenation and Catalysis
- Marine Sponges and Natural Products
- Catalytic C–H Functionalization Methods
- Atmospheric chemistry and aerosols
- Molecular spectroscopy and chirality
- Phosphorus compounds and reactions
- Catalytic Cross-Coupling Reactions
- Various Chemistry Research Topics
- Natural product bioactivities and synthesis
- Atmospheric Ozone and Climate
- Protein Structure and Dynamics
- Atmospheric aerosols and clouds
- Microbial Metabolism and Applications
- Antimicrobial Peptides and Activities
- Plant biochemistry and biosynthesis
Purdue University West Lafayette
2011-2023
Center for Cancer Research
2005-2013
Purdue University Institute for Cancer Research
2008
Target (United States)
2005
Texas A&M University
2005
Frederick National Laboratory for Cancer Research
2005
National Cancer Institute
2005
Columbia University
1988-1990
Yale University
1990
Shell (United States)
1984
Abstract An integrated molecular modeling system for designing and studying organic bioorganic molecules their complexes using mechanics is described. The graphically controlled, atom‐based allows the construction, display manipulation of having as many 10,000 atoms provides interactive, state‐of‐the‐art on any subset up to 1,000 atoms. semiautomates graphical construction analysis complex structures ranging from polycyclic biopolymers mixed complexes. We have placed emphasis providing...
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTRETRACTIONThis article has been retracted. View the notice.Asymmetric Catalysis of Strecker Amino Acid Synthesis by a Cyclic DipeptideMani S. Iyer, Kenneth M. Gigstad, Nivedita D. Namdev, and Mark LiptonView Author Information Department Chemistry, Purdue University West Lafayette, Indiana 47907 Cite this: J. Am. Chem. Soc. 1996, 118, 20, 4910–4911Publication Date (Web):May 22, 1996Publication History Received8 August 1995Published online22...
Abstract A general algorithm is described which exhaustively searches conformational space using an internal coordinate tree search. Using only geometrical operations and a set of criteria for eliminating chemically unreasonable structures, the generates starting geometries optimization by molecular mechanics. An implementation this exceedingly fast finds all known minima, as well several new ones, four test alkanes. This method makes feasible global molecules with up to 10 9 possibilities.
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTFacile and Efficient Guanylation of Amines Using Thioureas Mukaiyama's ReagentYaw Fui Yong, Jennifer A. Kowalski, Mark LiptonView Author Information Department Chemistry, Purdue University, West Lafayette, Indiana 47907 Cite this: J. Org. Chem. 1997, 62, 5, 1540–1542Publication Date (Web):March 7, 1997Publication History Received25 November 1996Published online7 March 1997Published inissue 1...
The C2−C6 (Schmittel)/ene cyclization of enyne-allenes is studied by a combination kinetic isotope effects, theoretical calculations, and dynamics trajectories. For the allenol acetate 9, effect (kCH3/kCD3) approximately 1.43. interpreted in terms highly asynchronous transition state near concerted/stepwise boundary. This supported density functional theory calculations that locate structure for concerted ene reaction. However, both experimental system model reaction were unable to formation...
Abstract. Isoprene hydroxynitrates (IN) are tracers of the photochemical oxidation isoprene in high NOx environments. Production and loss IN have a significant influence on cycle tropospheric O3 chemistry. To better understand chemistry, series reaction chamber experiments was conducted to determine yield from photooxidation at NO concentrations (> 100 ppt). By combining experimental data calculated isomer distributions, total 9(+4/−3) % derived. The result applied zero-dimensional model...
Abstract. The production of atmospheric organic nitrates (RONO2) has a large impact on air quality and climate due to their contribution secondary aerosol influence tropospheric ozone concentrations. Since control the fate gas phase NOx (NO + NO2), byproduct anthropogenic combustion processes, reactivity is great interest. While many relevant still uncertain, one significant reactive pathway, condensed hydrolysis, recently been identified as potential sink for nitrate species. partitioning...
Two patients with phosphofructokinase (PFK) deficiency had exercise intolerance and increased serum activity of creatine kinase; one presented hemolytic anemia, hyperuricemia, gouty arthritis. The glycogen concentration in the muscle these was about twice normal. PFK virtually absent muscle, but antibodies against M subunits normal human showed cross-reacting material from both patients. level red blood cells, studied case, lower than patient parents. Morphologically, there extensive...
Four model dipeptides, Ac-ψ[CSNH]-Gly-NHMe, Ac-Gly-ψ[CSNH]-NHMe, Ac-ψ[CSNH]-Ala-NHMe, and Ac-Ala-ψ[CSNH]-NHMe, each containing a thioamide bond, were studied by high-level ab initio calculations. For compound, conformational potential energy surface was generated constrained optimization at the HF/6-31G*//HF/6-31G* level of 144 starting geometries, resulting from systematic variation two flexible backbone torsions φ ψ. Selected regions used as points for full geometry MP2/6-31G*//MP2/6-31G*...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCyclic Hexapeptides and Chimeric Peptides as Mimics of TendamistatFelicia A. Etzkorn, Tao Guo, Mark Lipton, Steven D. Goldberg, Paul BartlettCite this: J. Am. Chem. Soc. 1994, 116, 23, 10412–10425Publication Date (Print):November 1, 1994Publication History Published online1 May 2002Published inissue 1 November 1994https://pubs.acs.org/doi/10.1021/ja00102a008https://doi.org/10.1021/ja00102a008research-articleACS PublicationsRequest reuse...
N-Fmoc-(2S,3S,4R)-3,4-dimethylglutamine (6) was synthesized from tert-butyl N-Boc-(2S,3S,4R)-dimethylpyroglutamate (13). This synthesis involved selective deprotection of a Boc group lactam nitrogen in the presence ester, Fmoc protection lactam, and lanthanide-catalyzed transamidation reaction Fmoc-protected using ammonia dimethylaluminum chloride. The scope Lewis acid-catalyzed acylated lactams explored through variation lanthanide, acyl group, amine, aluminum reagent. reactivity various...
The cytotoxic, cyclic heptadepsipeptide, natural product callipeltin B was synthesized on a solid-phase support in 15% overall yield. Comparison of the 1H NMR spectra three synthetic isomers with those confirmed configurational reassignment its threonine residues as d-allothreonine and assignment configuration β-methoxytyrosine residue (2R,3R).
The cyclic dipeptide cyclo[(R)-His-(R)-Phe] (1) has been known since 1981 to catalyze the enantioselective formation of cyanohydrins from aldehydes and HCN. Although 1 proved be very effective in production optically active cyanohydrins, precise structure its catalytically form remains unresolved. reaction 3-phenoxybenzaldehyde HCN presence also shown exhibit autocatalysis: product (S)-3-phenoxymandelonitrile reacts with a new, more catalytic species. It is now demonstrated that this...
Resonant two-photon ionization (R2PI), resonant ion-dip infrared (RIDIR), and UV-UV hole-burning spectroscopies have been employed to obtain conformation-specific ultraviolet spectra under supersonic expansion conditions for O-(2-acetamidoethyl)-N-acetyltyramine (OANAT), a doubly substituted aromatic in which amide-containing alkyl alkoxy side chains are located para positions on phenyl ring. For comparison, three single-chain analogs were also studied: (i) N-phenethyl-acetamide (NPEA), (ii)...
Abstract HMG-CoA reductase (HMGR), a rate-limiting enzyme of the mevalonate pathway in Gram-positive pathogenic bacteria, is an attractive target for development novel antibiotics. In this study, we report crystal structures HMGR from Enterococcus faecalis (efHMGR) apo and liganded forms, highlighting several unique features enzyme. Statins, which inhibit human with nanomolar affinity, perform poorly against bacterial homologs. We also potent competitive inhibitor (Chembridge2 ID 7828315 or...
Two possible isomers of the natural product callipeltin E (1, 5) were synthesized by using an Fmoc-based solid-phase strategy in 7 steps, 20% and 26% overall yields, respectively. The (1)H NMR spectrum synthetic 5 correlated closely with that product, whereas 1 did not, providing confirmation configurational reassignment N-terminal residue as D-allothreonine. This result strongly implies corresponding related cyclic depsipeptides callipeltins A B should also be considered a D-allothreonine residue.
The electronic factors influencing the competition between C2−C7 (Myers−Saito) and C2−C6 (Schmittel) cyclizations of 1,2,4-heptatrien-6-yne 1-ethynyl-2-propadienylbenzene are investigated using Becke3LYP/6-31G* calculations. relative energies biradical products formed upon cyclization calculated a simple bond additivity estimate by direct calculation. Both approaches predict that benzannulation stabilizes bis-dehydromethylfulvene forms with respect to ca. 10 kcal/mol. Transition state...