Physical Sciences and Mathematics Commons^™

Secondary Structure Adopted By The Gly-Gly-X Repetitive Regions Of Dragline Spider Silk, Geoffrey M Gray, Arjan Van Der Vaart, Chengchen Guo, Justin Jones, David Onofrei, Brian R Cherry, Randolph V Lewis, Jeffery L Yarger, Gregory P Holland

Chemistry Faculty Publications

Solid-state NMR and molecular dynamics (MD) simulations are presented to help elucidate the molecular secondary structure of poly(Gly-Gly-X), which is one of the most common structural repetitive motifs found in orb-weaving dragline spider silk proteins. The combination of NMR and computational experiments provides insight into the molecular secondary structure of poly(Gly-Gly-X) segments and provides further support that these regions are disordered and primarily non-β-sheet. Furthermore, the combination of NMR and MD simulations illustrate the possibility for several secondary structural elements in the poly(Gly-Gly-X) regions of dragline silks, including β-turns, 3

Giant Electrorheological Fluids With Ultrahigh Electrorheological Efficiency Based On A Micro/Nano Hybrid Calcium Titanyl Oxalate Composite, Jinghua Wu, Zhenyang Song, Fenghua Liu, Jianjun Guo, Yuchuan Cheng, Shengqian Ma, Gaojie Xu

Chemistry Faculty Publications

A novel micro/nanoparticle hybrid calcium titanyl oxalate electrorheological (ER) material composed of micron-sized spindly particles and nanometer-sized irregular particles was successfully fabricated. The giant ER fluid based on the composite exhibits enhanced not only yield stress but also low field-off viscosity, thereby resulting in an ultrahigh ER efficiency that greatly exceeds that of any existing giant ER (GER) material. The synergistic effect between the spindly microparticles and irregular nanoparticles discovered in this study suggests a promising method for solving the long-standing ER efficiency problems. Moreover, the one-step synthesis approach presented in this work can be readily expanded for mass production …

Towards An Understanding Of The Propensity For Crystalline Hydrate Formation By Molecular Compounds, Alankriti Bajpai, Hayley S Scott, Tony Pham, Kai-Jie Chen, Brian Space, Matteo Lusi, Miranda L Perry, Michael J Zaworotko

Chemistry Faculty Publications

Hydrates are technologically important and ubiquitous yet they remain a poorly understood and understudied class of molecular crystals. In this work, we attempt to rationalize propensity towards hydrate formation through crystallization studies of molecules that lack strong hydrogen-bond donor groups. A Cambridge Structural Database (CSD) survey indicates that the statistical occurrence of hydrates in 124 molecules that contain five- and six-membered N-heterocyclic aromatic moieties is 18.5%. However, hydrate screening experiments on a library of 11 N-heterocyclic aromatic compounds with at least two acceptor moieties and no competing hydrogen-bond donors or acceptors reveals that over 70% of this group …

Imparting Amphiphobicity On Single-Crystalline Porous Materials., Qi Sun, Hongming He, Wen-Yang Gao, Briana Aguila, Lukasz Wojtas, Zhifeng Dai, Jixue Li, Yu-Sheng Chen, Feng-Shou Xiao, Shengqian Ma

Chemistry Faculty Publications

The sophisticated control of surface wettability for target-specific applications has attracted widespread interest for use in a plethora of applications. Despite the recent advances in modification of non-porous materials, surface wettability control of porous materials, particularly single crystalline, remains undeveloped. Here we contribute a general method to impart amphiphobicity on single-crystalline porous materials as demonstrated by chemically coating the exterior of metal-organic framework (MOF) crystals with an amphiphobic surface. As amphiphobic porous materials, the resultant MOF crystals exhibit both superhydrophobicity and oleophobicity in addition to retaining high crystallinity and intact porosity. The chemical shielding effect resulting from the amphiphobicity of …

Intramolecular 1,5-C(Sp3)–H Radical Amination Via Co(Ii)-Based Metalloradical Catalysis For Five-Membered Cyclic Sulfamides, Hongjian Lu, Kai Lang, Huiling Jiang, Lukasz Wojtas, X Peter Zhang

Chemistry Faculty Publications

Co(II)-based metalloradical catalysis (MRC) proves effective for intramolecular 1,5-C–H amination of sulfamoyl azides under neutral and nonoxidative conditions, providing a straightforward approach to access strained 5-membered cyclic sulfamides with nitrogen gas as the only byproduct. The metalloradical amination system is applicable to different types of C(sp³)–H bonds and has a high degree of functional group tolerance. Additional features of the Co(II)-catalyzed 1,5-C–H amination include excellent chemoselectivity toward allylic and propargylic C–H bonds. The unique reactivity and selectivity profile of the Co(II)-catalyzed 1,5-C–H amination is attributed to the underlying radical mechanism of MRC.

Identification Of Ecdysone Hormone Receptor Agonists As A Therapeutic Approach For Treating Filarial Infections, Amruta S Mhashilkar, Sai L Vankayala, Canhui Liu, Fiona Kearns, Priyanka Mehrotra, George Tzertzinis, Subba R Palli, H. Lee Woodcock Iii, Thomas R Unnasch

Chemistry Faculty Publications

BACKGROUND: A homologue of the ecdysone receptor has previously been identified in human filarial parasites. As the ecdysone receptor is not found in vertebrates, it and the regulatory pathways it controls represent attractive potential chemotherapeutic targets.

METHODOLOGY/ PRINCIPAL FINDINGS: Administration of 20-hydroxyecdysone to gerbils infected with B. malayi infective larvae disrupted their development to adult stage parasites. A stable mammalian cell line was created incorporating the B. malayi ecdysone receptor ligand-binding domain, its heterodimer partner and a secreted luciferase reporter in HEK293 cells. This was employed to screen a series of ecdysone agonist, identifying seven agonists active at sub-micromolar concentrations. …

Molecular Mechanism Of Protein Kinase Recognition And Sorting By The Hsp90 Kinome-Specific Cochaperone Cdc37, Dimitra Keramisanou, Adam Aboalroub, Ziming Zhang, Wenjun Liu, Devon Marshall, Andrea Diviney, Randy W. Larsen, Ralf Landgraf, Ioannis Gelis

Chemistry Faculty Publications

Despite the essential functions of Hsp90, little is known about the mechanism that controls substrate entry into its chaperone cycle. We show that the role of Cdc37 cochaperone reaches beyond that of an adaptor protein and find that it participates in the selective recruitment of only client kinases. Cdc37 recognizes kinase specificity determinants in both clients and nonclients and acts as a general kinase scanning factor. Kinase sorting within the client-to-nonclient continuum relies on the ability of Cdc37 to challenge the conformational stability of clients by locally unfolding them. This metastable conformational state has high affinity for Cdc37 and forms …

Agonist-Mediated Activation Of Sting Induces Apoptosis In Malignant B Cells, Chih-Hang Anthony Tang, Joseph A. Zundell, Sujeewa Ranatunga, Cindy Lin, Yulia Nefedova, Juan R. Del Valle, Chih-Chi Andrew Hu

Chemistry Faculty Publications

Endoplasmic reticulum (ER) stress responses through the IRE-1/XBP-1 pathway are required for the function of STING (TMEM173), an ER-resident transmembrane protein critical for cytoplasmic DNA sensing, IFN production, and cancer control. Here we show that the IRE-1/XBP-1 pathway functions downstream of STING and that STING agonists selectively trigger mitochondria-mediated apoptosis in normal and malignant B cells. Upon stimulation, STING was degraded less efficiently in B cells, implying that prolonged activation of STING can lead to apoptosis. Transient activation of the IRE-1/XBP-1 pathway partially protected agonist-stimulated malignant B cells from undergoing apoptosis. In Eμ-TCL1 mice with chronic lymphocytic leukemia, injection of …

Mechanistic Binding Insights For 1-Deoxy-D-Xylulose-5-Phosphatesynthase, The Enzyme Catalyzing The First Reaction Of Isoprenoid Biosynthesis In The Malaria-Causing Protists, Plasmodium Falciparum And Plasmodium Vivax, Matthew R. Battistini, Christopher Shoji, Sumit Handa, Leonid Breydo, David J. Merkler

Chemistry Faculty Publications

We have successfully truncated and recombinantly-expressed 1-deoxy-D-xylulose-5-phosphate synthase (DXS) from both Plasmodium vivax and Plasmodium falciparum. We elucidated the order of substrate binding for both of these ThDP-dependent enzymes using steady-state kinetic analyses, dead-end inhibition, and intrinsic tryptophan fluorescence titrations. Both enzymes adhere to a random sequential mechanism with respect to binding of both substrates: pyruvate and D-glyceraldehyde-3-phosphate. These findings are in contrast to other ThDP-dependent enzymes, which exhibit classical ordered and/or ping-pong kinetic mechanisms. A better understanding of the kinetic mechanism for these two Plasmodial enzymes could aid in the development of novel DXS-specific inhibitors that might prove useful …

Glycine N-Acyltransferase-Like 3 Is Responsible For Long-Chain N-Acylglycine Formation In N18Tg2 Cells, Kristen A Jeffries, Daniel R Dempsey, Emma K Farrell, Ryan L Anderson, Gabrielle J Garbade, Tatyana S Gurina, Imran Gruhonjic, Carly A Gunderson, David J Merkler

Chemistry Faculty Publications

Long-chain fatty acid amides are signaling lipids found in mammals and other organisms; however, details of the metabolic pathways for the N-acylglycines and primary fatty acid amides (PFAMs) have remained elusive. Heavy-labeled precursor and subtraction lipidomic experiments in mouse neuroblastoma N18TG2 cells, a model cell line for the study of fatty acid amide metabolism, establish the biosynthetic pathways for the N-acylglycines and the PFAMs. We provide evidence that the N-acylglycines are formed by a long-chain specific glycine-conjugating enzyme, glycine N-acyltransferase-like 3 (GLYATL3). siRNA knockdown of GLYATL3 in the N18TG2 cells resulted in a decrease in the levels of the N-acylglycines …

Restricted Mobility Of Specific Functional Groups Reduces Anti-Cancer Drug Activity In Healthy Cells, Murillo L. Martins, Rosanna Ignazzi, Juergen Eckert, Benjamin Watts, Ramon Kaneno, Willian F Zambuzzi, Luke Daemen, Margarida J Saeki, Heloisa N Bordallo

Chemistry Faculty Publications

The most common cancer treatments currently available are radio- and chemo-therapy. These therapies have, however, drawbacks, such as, the reduction in quality of life and the low efficiency of radiotherapy in cases of multiple metastases. To lessen these effects, we have encapsulated an anti-cancer drug into a biocompatible matrix. In-vitro assays indicate that this bio-nanocomposite is able to interact and cause morphological changes in cancer cells. Meanwhile, no alterations were observed in monocytes and fibroblasts, indicating that this system might carry the drug in living organisms with reduced clearance rate and toxicity. X-rays and neutrons were used to investigate the …

Creation Of A New Type Of Ion Exchange Material For Rapid, High-Capacity, Reversible And Selective Ion Exchange Without Swelling And Entrainment, Baiyan Li, Yiming Zhang, Dingxuan Ma, Zhenyu Xing, Tianliang Ma, Zhan Shi, Xiulei Ji, Shengqian Ma

Chemistry Faculty Publications

Ion-exchange materials, currently dominated by resins, are widely used in a plethora of areas. However, the drawbacks of conventional resins necessitate the creation of a new model of ion exchange materials that feature controllable swelling, easily accessible ion exchange sites, high ion exchange capacity, fast ion exchange kinetics, and high chemical stability as illustrated herein in the context of functionalizing a porous organic polymer (POP) with ion exchange groups. The advantages of POP-based ion exchange materials in comparison with conventional resins and other types of ion exchange materials have been highlighted through an evaluation of their performances in scavenging precious …

New Urjc-1 Material With Remarkable Stability And Acid-Base Catalytic Properties, Pedro Leo, Ferdnando Martinez, Guillermo Calleja, David Briones, Lukasz Wojtas

Chemistry Faculty Publications

Emerging new metal-organic structures with tunable physicochemical properties is an exciting research field for diverse applications. In this work, a novel metal-organic framework Cu(HIT)(DMF)_0.5, named URJC-1, with a three-dimensional non-interpenetrated utp topological network, has been synthesized. This material exhibits a microporous structure with unsaturated copper centers and imidazole–tetrazole linkages that provide accessible Lewis acid/base sites. These features make URJC-1 an exceptional candidate for catalytic application in acid and base reactions of interest in fine chemistry. The URJC-1 material also displays a noteworthy thermal and chemical stability in different organic solvents of different polarity and boiling water. Its catalytic …

Crystal Structure Of Ethyl 4-[(E)-(4-Hy-Droxy-3-Meth-Oxy-Benzyl-Idene)Amino]-Benzoate: A P-Hy-Droxy Schiff Base, Jing Ling, Padmini Kavuru, Lukasz Wojtas, Keith Chadwick

Chemistry Faculty Publications

The title p-hy-droxy Schiff base, C17H17NO4, was synthesized via the condensation reaction of benzocaine with vanillin. The benzyl-idine and benzoate rings are inclined to one another by 24.58 (8)°, and the conformation about the C=N bond is E. In the crystal, mol-ecules are linked by O-H⋯N hydrogen bonds, forming zigzag chains propagating along [010]. Adjacent chains are linked by C-H⋯π and weak offset π-π inter-actions [inter-centroid distance = 3.819 (1) Å], forming sheets parallel to (10-2).

Nucleophile Promoted Gold Redox Catalysis With Diazonium Salts: C-Br, C-S And C-P Bond Formation Through Catalytic Sandmeyer Coupling, Haihui Peng, Rong Cai, Chang Xu, Hao Chen, Xiaodong Shi

Chemistry Faculty Publications

Gold-catalyzed C-heteroatom (C-X) coupling reactions are evaluated without using sacrificial oxidants. Vital to the success of this methodology is the nucleophile-assisted activation of aryldiazonium salts, which could be an effective oxidant for converting Au(i) to Au(iii) even without the addition of an assisting ligand or photocatalyst. By accelerating the reaction kinetics to outcompete C-C homo-coupling or diazonium dediazoniation, gold-catalyzed Sandmeyer reactions were achieved with different nucleophiles, forming C-Br, C-S and C-P bonds in high yields and selectivities.

Inactivation Of Peptidylglycine Α-Hydroxylating Monooxygenase By Cinnamic Acid Analogs, Neil R. Mcintyre, Edward W. Lowe Jr, Matthew R. Battistini, James W. Leahy, David J. Merkler

Chemistry Faculty Publications

Peptidylglycine α-amidating monooxygenase (PAM) is a bifunctional enzyme that catalyzes the final reaction in the maturation of α-amidated peptide hormones. Peptidylglycine α-hydroxylating monooxygenase (PHM) is the PAM domain responsible for the copper-, ascorbate- and O₂-dependent hydroxylation of a glycine-extended peptide. Peptidylamidoglycolate lyase is the PAM domain responsible for the Zn(II)-dependent dealkylation of the α-hydroxyglycine-containing precursor to the final α-amidated peptide. We report herein that cinnamic acid and cinnamic acid analogs are inhibitors or inactivators of PHM. The inactivation chemistry exhibited by the cinnamates exhibits all the attributes of a suicide-substrate. However, we find no evidence for the formation …

Crystal Engineering Of A Family Of Hybrid Ultramicroporous Materials Based Upon Interpenetration And Dichromate Linkers, Hayley S. Scott, Naoki Ogiwara, Kai-Jie Chen, David G. Madden, Tony Pham, Katherine Forrest, Brian Space, Satoshi Horike, John J. Perry Iv, Susumu Kitagawa, Michael J. Zaworotko

Chemistry Faculty Publications

A new family of 2-fold interpenetrated primitive cubic (pcu) networks of formula [M(L)₂(Cr₂O₇)]_n (M = Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺; L = 4,4′-azopyridine), DICRO-3-M-i, has been synthesised and their structures, permanent porosity and gas sorption properties were comprehensively characterised. Molecular simulations indicate that CO₂ molecules occupy both of the two distinct ultramicropores that run through this isostructural series. The orientation of the Cr₂O₇²⁻ pillars is thought to contribute to high isosteric enthalpy of adsorption (Q_st) …

Traits And Roles Of Jonas Kamlet, Pioneering Chemistry Consultant, As A Guide To Contemporary Inventors, Dean F. Martin, Autumn S. Thompson

Chemistry Faculty Publications

As state universities feel economic pinches of reduced support from state legislatures, and as sources of federal funding for supported research projects face additional challenges, other sources of support need to be found. Two sources under consideration are royalties and licensing fees for successful patents. A good example of a successful developer of patents was Jonas Kamlet, Ph.D. (1914‐1960), who was an early consultant in chemical and other matters and was the successful co-owner, with his wife Edna, of the Kamlet Laboratories. The roles that he played in his career can, we believe, provide good examples for contemporary researchers in …

Nonexistent Compounds As A Guide To Innovation, Dean F. Martin, Barbara B. Martin

Chemistry Faculty Publications

A study of nonexistent compounds can be a useful exercise in gaining insight into the factors that can inhibit innovation. Several reasons are suggested: lack of financial support, disinterest in preparing compounds that lack evident utility, notable synthetic challenges with inadequate rewards, inhibition by well-established contemporary knowledge, and invalid interpolations.

Kamlet Laboratories And Clinitest: Idea To Product, Dean F. Martin, Brodie A. Reiger

Chemistry Faculty Publications

This paper examines the process of development of Clinitest pills that could be used in clinics or physicians' offices for rapid, convenient analysis of glucose and other components of clinical interest. It was invented by Dr. Jonas Kamlet. We were able to follow the process because his papers are accessible (as The Kamlet Laboratories Collection) at the University of South Florida Library. The accessibility of these papers gives an opportunity to see steps in the development of a successful product from conception to patent and commercialization. Kamlet, a consulting chemist, took the invention to Miles Laboratories of Elkhart, Indiana, in …

The Kamlet Laboratories Collection At The University Of South Florida, Dean F. Martin, Karina Bidani

Chemistry Faculty Publications

Jonas Kamlet (1914-1960) and his wife Edna (1915- 2011) founded the Kamlet Laboratory (as it was then called) in 1941 (I). It was in many ways a pioneering consulting laboratory that was unique for its approach and creativity. In 2006, the collected papers of the Kamlet Laboratories that were housed in two storage units in Sarasota, Florida, were donated to the University of South Florida (USF) Library, Tampa Campus, as noted elsewhere (I). This paper describes the background of the laboratory and indicates the potential value of the material in the Kamlet Chemical Laboratories Collection. The collection came to USF …

Jonas Kamlet (1914-1960) Chemist/Entrepreneur, Dean F. Martin, Barbara B. Martin

Chemistry Faculty Publications

Jonas Kamlet, Ph.D., as a chemist, inventor, and a significant entrepreneur who founded Kamlet Laboratories in New York City that became the model of a successful consulting firm. Among his hundreds of patents and inventions were a tablet that could be used to measure glucose in urine, a treated strip that could detect pregnancy, a fodder for ruminants that used newsprint, and biuret (a self-condensation product of urea) that could be used as a non-protein component of fodder. Following his death in an airplane collision on December 16, 1960, his wife and collaborator (and later a resident of Florida) carried …