Molecular Biology Commons^™

Functional Association Between Three Archaeal Aminoacyl-Trna Synthetases, Mette Praetorius-Ibba, Corinne D. Hausmann, Molly Paras, Theresa E. Rogers, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Aminoacyl-tRNA synthetases (aaRSs) are responsible for attaching amino acids to their cognate tRNAs during protein synthesis. In eukaryotes aaRSs are commonly found in multi-enzyme complexes, although the role of these complexes is still not completely clear. Associations between aaRSs have also been reported in archaea, including a complex between prolyl-(ProRS) and leucyl-tRNA synthetases (LeuRS) in Methanothermobacter thermautotrophicus that enhances tRNA^Pro aminoacylation. Yeast two-hybrid screens suggested that lysyl-tRNA synthetase (LysRS) also associates with LeuRS in M. thermautotrophicus. Co-purification experiments confirmed that LeuRS, LysRS, and ProRS associate in cell-free extracts. LeuRS bound LysRS and ProRS with a comparable K_{D …}

A Genomic Approach To Identify Regulatory Nodes In The Transcriptional Network Of Systemic Acquired Resistance In Plants, Dong Wang, Nita Amornsiripanitch, Xinnian Dong

Dong Wang

Many biological processes are controlled by intricate networks of transcriptional regulators. With the development of microarray technology, transcriptional changes can be examined at the whole-genome level. However, such analysis often lacks information on the hierarchical relationship between components of a given system. Systemic acquired resistance (SAR) is an inducible plant defense response involving a cascade of transcriptional events induced by salicylic acid through the transcription cofactor NPR1. To identify additional regulatory nodes in the SAR network, we performed microarray analysis on Arabidopsis plants expressing the NPR1-GR (glucocorticoid receptor) fusion protein. Since nuclear translocation of NPR1-GR requires dexamethasone, we were able …

The Role Of A Conserved Serine Residue Within Hydrogen Bonding Distance Of Fad In Redox Properties And The Modulation Of Catalysis By Ca2+/Calmodulin Of Constitutive Nitric-Oxide Synthases, Satya Prakash Panda, Ying Tong Gao, Linda J. Roman, Pavel Marta´Sek, John C. Salerno, Bettie Masters

Faculty and Research Publications

The crystal structure of the neuronal nitric-oxide synthase (nNOS) NADPH/FAD binding domain indicated that Ser-1176 is within hydrogen bonding distance of Asp-1393 and the O4 atom of FAD and is also near the N5 atom of FAD (3.7Å). This serine residue is conserved in most of the ferredoxin-NADP⁺ reductase family of proteins and is important in electron transfer. In the present study, the homologous serines of both nNOS (Ser-1176) and endothelial nitric-oxide synthase (eNOS) (Ser-942) were mutated to threonine and alanine. Both substitutions yielded proteins that exhibited decreased rates of electron transfer through the flavin domains, in the presence …

Reconstitution Of Protein Targeting To The Inner Envelope Membrane Of Chloroplasts, Ming Li, Danny Schnell

Danny Schnell

The chloroplast envelope plays critical roles in the synthesis and regulated transport of key metabolites, including intermediates in photosynthesis and lipid metabolism. Despite this importance, the biogenesis of the envelope membranes has not been investigated in detail. To identify the determinants of protein targeting to the inner envelope membrane (IM), we investigated the targeting of the nucleus-encoded integral IM protein, atTic40. We found that pre-atTic40 is imported into chloroplasts and processed to an intermediate size (int-atTic40) before insertion into the IM. Int-atTic40 is soluble and inserts into the IM from the internal stromal compartment. We also show that atTic40 and …

The Structure And Function Of Frataxin, Krisztina Z. Bencze, Kalyan C. Kondapalli, Jeremy D. Cook, Stephen Mcmahon, César Millán-Pacheco, Nina Pastor, Timothy L. Stemmler

Biochemistry and Molecular Biology Faculty Publications

Frataxin, a highly conserved protein found in prokaryotes and eukaryotes, is required for efficient regulation of cellular iron homeostasis. Humans with a frataxin deficiency have the cardio- and neurodegenerative disorder Friedreich’s ataxia, commonly resulting from a GAA trinucleotide repeat expansion in the frataxin gene. While frataxin’s specific function remains a point of controversy, a general consensus is the protein assists in controlling cellular iron homeostasis by directly binding iron. This review focuses on the structural and biochemical aspects of iron binding by the frataxin orthologs and outlines molecular attributes that may help explain the protein’s role in different cellular pathways.

The Structure Of Escherichia Coli Signal Recognition Particle Revealed By Scanning Transmission Electron Microscopy, Lain L. Mainprize, Daniel R. Beniac, Elena Falkovskaia, Robert M. Cleverley, Lila Gierasch, F. Peter Ottensmeyer, David W. Andrews

Lila Gierasch

Structural studies on various domains of the ribonucleoprotein signal recognition particle (SRP) have not converged on a single complete structure of bacterial SRP consistent with the biochemistry of the particle. We obtained a three-dimensional structure for Escherichia coli SRP by cryoscanning transmission electron microscopy and mapped the internal RNA by electron spectroscopic imaging. Crystallographic data were fit into the SRP reconstruction, and although the resulting model differed from previous models, they could be rationalized by movement through an interdomain linker of Ffh, the protein component of SRP. Fluorescence resonance energy transfer experiments determined interdomain distances that were consistent with our …

Biophotonics: Electrochemiluminescence At Microelectrodes During Pcr Amplification Of Dna, Rosemary L. Smith, Scott Collins

University of Maine Office of Research Administration: Grant Reports

This project investigates a new technique for in situ quantification of Polymerase Chain Reaction (PCR) amplification products using electrochemiluminescence (ECL). The technique implements the highly sensitive, ECL detection and quantification of tris(2,2'bipyridyl) ruthenium (II) labeled DNA. This method is expected to yield significant improvement in speed, cost and performance over existing quantitative PCR methods, by reducing the number and quantity of reagents, reducing the number of sample preparation steps, increasing sensitivity, and shortening analysis time.

A Comprehensive Structure–Function Analysis Of Arabidopsis Sni1 Defines Essential Regions And Transcriptional Repressor Activity, Rebecca A. Mosher, Wendy E. Durrant, Dong Wang, Jungi Song, Xinnian Dong

Dong Wang

The expression of systemic acquired resistance (SAR) in plants involves the upregulation of many Pathogenesis-Related (PR) genes, which work in concert to confer resistance to a broad spectrum of pathogens. Because SAR is a costly process, SAR-associated transcription must be tightly regulated. Arabidopsis thaliana SNI1 (for Suppressor of NPR1, Inducible) is a negative regulator of SAR required to dampen the basal expression of PR genes. Whole genome transcriptional profiling showed that in the sni1 mutant, Nonexpresser of PR genes (NPR1)–dependent benzothiadiazole S-methylester–responsive genes were specifically derepressed. Interestingly, SNI1 also repressed transcription when expressed in yeast, suggesting that it functions as …

Evaluation Of Toxicity Following Electrically Mediated Interleukin-12 Gene Delivery In A B16 Mouse Melanoma Model, Loree Heller, Kathleen Merkler, Jeffrey Westover, Yolmari Cruz, Domenico Coppola, Kaaron Benson, Adil Daud, Richard Heller

Bioelectrics Publications

PURPOSE: Interleukin-12 (IL-12) has potential as an immunotherapeutic agent for the treatment of cancer but is unfortunately associated with toxicity. Delivery of a plasmid encoding IL-12 with electroporation induces an antitumor effect in the B16 mouse melanoma model without serious side effects. To translate this observation to the clinic, an evaluation of toxicity was done in the mouse model.

EXPERIMENTAL DESIGN: Weight change, tumor response, blood chemistry and hematology values, and serum IL-12 levels were evaluated. Multiple tissues were analyzed histopathologically.

RESULTS: A pronounced reduction in tumor volume, including a large percentage of complete regressions, was observed after electrically mediated …

Biochemical Characterization Of The Major Sorghum Grain Peroxidase, Mamoudou H. Dicko, Harry Gruppen, Riet Hilhorst, Alphons G. J. Voragen, Willen W. H. Van Berkel

Pr. Mamoudou H. DICKO, PhD

The Study Of Nitric Oxide Synthase Expression, Function, And Regulation In The Renal Vasculature During Postnatal Renal Development, Brian Blake Ratliff

Theses and Dissertations in Biomedical Sciences

The newborn kidney is vulnerable to vasomotor acute renal failure (ARF) from adverse perinatal events or complications of prematurity. Nitric oxide (NO) vasodilation is vitally protective in this type of ARF, but its relationship with other vasoactive factors, such as angiotensin II (AII) has not been examined. In the immature kidney, nitric oxide synthase (NOS) isoforms, specifically eNOS and nNOS, are developmentally regulated, but their specific role and regulation are unknown.

The enhanced vasodilatory role of NO in the immature kidney was hypothesized to be attributed to regulatory, expressional, and functional differences in eNOS and nNOS isoforms from the adult. …

Aspartyl-Trna Synthetase Is The Target Of Peptidenucleotide Antibiotic Microcin C, Anastasia Metlitskaya, Teymur Kazakov, Aigar Kommer, Olga Pavlova, Mette Praetorius-Ibba, Michael Ibba, Igor Krasheninnkov, Vyacheslav Kolb, Inessa Khmel, Konstantin Severinov

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Microcin C is a ribosome-synthesized heptapeptide that contains a modified adenosine monophosphate covalently attached to the C-terminal aspartate. Microcin C is a potent inhibitor of bacterial cell growth. Based on the in vivo kinetics of inhibition of macromolecular synthesis, Microcin C targets translation, through a mechanism that remained undefined. Here, we show that Microcin C is a subject of specific degradation inside the sensitive cell. The product of degradation, a modified aspartyl-adenylate containing an N-acylphosphoramidate linkage, strongly inhibits translation by blocking the function of aspartyl-tRNA synthetase.

Three-Dimensional Structure Of The Bacterial Cell Wall Peptidoglycan, Samy O. Meroueh, Krisztina Z. Bencze, Dusan Hesek, Mijoon Lee, Timothy L. Stemmler, Shahriar Mobashery

Biochemistry and Molecular Biology Faculty Publications

The 3D structure of the bacterial peptidoglycan, the major constit- uent of the cell wall, is one of the most important, yet still unsolved, structural problems in biochemistry. The peptidoglycan comprises alternating N-acetylglucosamine (NAG) and N-acetylmu- ramic disaccharide (NAM) saccharides, the latter of which has a peptide stem. Adjacent peptide stems are cross-linked by the transpeptidase enzymes of cell wall biosynthesis to provide the cell wall polymer with the structural integrity required by the bacte- rium. The cell wall and its biosynthetic enzymes are targets of antibiotics. The 3D structure of the cell wall has been elusive because of its …

The Importance Of Maltose In Transitory Starch Breakdown, Yan Lu, Thomas Sharkey

Yan Lu

No abstract provided.

C To U Editing Stimulates A To I Editing In The Anticodon Loop Of A Cytoplasmic Threonyl Trna In Trypanosoma Brucei, Mary Anne T. Rubio, Frank L. Ragone, Kirk W. Gaston, Michael Ibba, Juan D. Alfonzo

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Editing of tRNAs is widespread in nature and either changes the decoding properties or restores the folding of a tRNA. Unlike the phylogenetically disperse adenosine (A) to inosine (I) editing, cytosine (C) to uridine (U) editing has only been previously described in organellar tRNAs. We have shown that cytoplasmic tRNA^Thr(AGU) undergoes two distinct editing events in the anticodon loop: C to U and A to I. In vivo, every inosine-containing tRNA^Thr is also C to U edited at position 32. In vitro, C to U editing stimulates conversion of A to I at the wobble base. Although …

Ethylene Stimulates Nutations That Are Dependent On The Etr1 Receptor, Brad M. Binder, Ronan C. O'Malley, Wuyi Wang, Tobias C. Zutz, Anthony B. Bleeker

Faculty Publications and Other Works -- Biochemistry, Cellular and Molecular Biology

Ethylene influences a number of processes in Arabidopsis (Arabidopsis thaliana) through the action of five receptors. In this study, we used high-resolution, time-lapse imaging to examine the long-term effects of ethylene on growing, etiolated Arabidopsis seedlings. These measurements revealed that ethylene stimulates nutations of the hypocotyls with an average delay in onset of over 6 h. The nutation response was constitutive in ctr1-2 mutants maintained in air, whereas ein2-1 mutants failed to nutate when treated with ethylene. Ethylene-stimulated nutations were also eliminated in etr1-7 loss-of-function mutants. Transformation of the etr1-7 mutant with a wild-type genomic ETR1 transgene rescued the nutation …

Soluble Fibrin Inhibits Monocyte Adherence And Cytotoxicity Against Tumor Cells: Implications For Cancer Metastasis, John Biggerstaff, Brandy Weidow, Jacqueline Vidosh, Judith Dexheimer, Shonak Patel, Pretesh Patel

Faculty Publications and Other Works -- Biochemistry, Cellular and Molecular Biology

Background Soluble fibrin (sFn) is a marker for disseminated intravascular coagulation and may have prognostic significance, especially in metastasis. However, a role for sFn in the etiology of metastatic cancer growth has not been extensively studied. We have reported that sFn cross-linked platelet binding to tumor cells via the major platelet fibrin receptor αIIbβ3, and tumor cell CD54 (ICAM-1), which is the receptor for two of the leukocyte β2 integrins (αLβ2 and aMβ2). We hypothesized that sFn may also affect leukocyte adherence, recognition, and killing of tumor cells. Furthermore, in a rat experimental metastasis model sFn pre-treatment of tumor cells …

Epichlorohydrin Cross-Linking Of Synthetic Dna Oligomers, Rami W. Zaharan, Julie T. Millard

Undergraduate Research Symposium (UGRS)

Epichlorohydrin (ECH), an important chemical in the synthetic polymer industry, is a bifunctional alkylating agent with the potential to form DNA interstrand crosslinks. Occupational exposure to this suspect carcinogen leads to chromosomal aberrations, and ECH has been shown to undergo reaction with DNA in vivo and in vitro. We are using denaturing polyacrylamide gel electrophoresis to assess cross-linking of synthetic DNA oligomers by both ECH and the related compound, epibromohydrin (EBH). Both epihalohydrins produce a low-mobility band on denaturing gels consistent with an interstrand cross-link. Moreover, the efficiencies, sequence preferences, reaction kinetics, and pH dependence differ for the two compounds, …

Direct Control Of Cell Cycle Gene Expression By Proto-Oncogene Product Actr, And Its Autoregulation Underlies Its Transforming Activity, Maggie C. Louie, Alexey S. Revenko, June X. Zou, Jennifer Yao, Hong-Wu Chen

Collected Faculty and Staff Scholarship

ACTR (also called AIB1 and SRC-3) was identified as a coactivator for nuclear receptors and is linked to multiple types of human cancer due to its frequent overexpression. However, the molecular mechanism of ACTR oncogenicity and its function independent of nuclear receptors remain to be defined. We demonstrate here that ACTR is required for both normal and malignant human cells to effectively enter S phase. RNA interference-mediated depletion and chromatin immunoprecipitation assays show that endogenous ACTR directly controls the expression of genes important for initiation of DNA replication, which include cdc6, cdc25A, MCM7, cyclin E, and Cdk2. Moreover, consistent with …

Heparin Modulates The 99-Loop Of Factor Ixa: Effects On Reactivity With Isolated Kunitz-Type Inhibitor Domains, Pierre F. Neuenschwander, Stephen R. Williamson, Armen Nalian, Kimberly J. Baker-Deadmond

Faculty Publications

Reactivity of factor IXa with basic pancreatic trypsin inhibitor is enhanced by low molecular weight heparin (enoxaparin). Previous studies by us have suggested that this effect involves allosteric modulation of factor IXa. We examined the reactivity of factor IXa with several isolated Kunitz-type inhibitor domains: basic pancreatic trypsin inhibitor, the Kunitz inhibitor domain of protease Nexin-2, and the first two inhibitor domains of tissue factor pathway inhibitor. We find that enhancement of factor IXa reactivity by enoxaparin is greatest for basic pancreatic trypsin inhibitor (>10-fold), followed by the second tissue factor pathway inhibitor domain (1.7-fold) and the Kunitz inhibitor …

Ethylene Stimulates Nutations That Are Dependent On The Etr1 Receptor, Brad M. Binder, Ronan C. O'Malley, Wuyi Wang, Tobias C. Zutz, Anthony B. Bleeker

Brad M. Binder

Ethylene influences a number of processes in Arabidopsis (Arabidopsis thaliana) through the action of five receptors. In this study, we used high-resolution, time-lapse imaging to examine the long-term effects of ethylene on growing, etiolated Arabidopsis seedlings. These measurements revealed that ethylene stimulates nutations of the hypocotyls with an average delay in onset of over 6 h. The nutation response was constitutive in ctr1-2 mutants maintained in air, whereas ein2-1 mutants failed to nutate when treated with ethylene. Ethylene-stimulated nutations were also eliminated in etr1-7 loss-of-function mutants. Transformation of the etr1-7 mutant with a wild-type genomic ETR1 transgene rescued the nutation …

Soluble Fibrin Inhibits Monocyte Adherence And Cytotoxicity Against Tumor Cells: Implications For Cancer Metastasis, John Biggerstaff, Brandy Weidow, Jacqueline Vidosh, Judith Dexheimer, Shonak Patel, Pretesh Patel

John Biggerstaff

Background Soluble fibrin (sFn) is a marker for disseminated intravascular coagulation and may have prognostic significance, especially in metastasis. However, a role for sFn in the etiology of metastatic cancer growth has not been extensively studied. We have reported that sFn cross-linked platelet binding to tumor cells via the major platelet fibrin receptor αIIbβ3, and tumor cell CD54 (ICAM-1), which is the receptor for two of the leukocyte β2 integrins (αLβ2 and aMβ2). We hypothesized that sFn may also affect leukocyte adherence, recognition, and killing of tumor cells. Furthermore, in a rat experimental metastasis model sFn pre-treatment of tumor cells …

Farnesylated Lamins, Progeroid Syndromes And Farnesyl Transferase Inhibitors, Michael Sinensky, A. E. Rusinol

Michael Sinensky

Three mammalian nuclear lamin proteins, lamin B1, lamin B2 and the lamin A precursor, prelamin A, undergo canonical farnesylation and processing at CAAX motifs. In the case of prelamin A, there is an additional farnesylation-dependent endoproteolysis, which is defective in two congenital diseases: Hutchinson-Gilford progeria (HGPS) and restrictive dermopathy (RD). These two diseases arise respectively from defects in the prelamin A substrate and the enzyme (ZmpSte24) that processes it. Recent work has shed light on the roles of the lamin proteins and the enzymes involved in their farnesylation-dependent maturation. Other experimental work, including mouse model studies, have examined the possibility …

Dna Damage Responses In Progeroid Syndromes Arise From Defective Maturation Of Prelamin A, Michael Sinensky, Y. Liu, A. Rusinol, Y. Wang, Y. Zou

Michael Sinensky

The genetic diseases Hutchinson-Gilford progeria syndrome (HGPS) and restrictive dermopathy (RD) arise from accumulation of farnesylated prelamin A because of defects in the lamin A maturation pathway. Both of these diseases exhibit symptoms that can be viewed as accelerated aging. The mechanism by which accumulation of farnesylated prelamin A leads to these accelerated aging phenotypes is not understood. Here we present evidence that in HGPS and RD fibroblasts, DNA damage checkpoints are persistently activated because of the compromise in genomic integrity. Inactivation of checkpoint kinases Ataxia-telangiectasia-mutated (ATM) and ATR (ATM- and Rad3-related) in these patient cells can partially overcome their …

Farnesylated Lamins, Progeroid Syndromes And Farnesyl Transferase Inhibitors, Michael Sinensky, A. E. Rusinol

Faculty Publications, Biological Sciences

Three mammalian nuclear lamin proteins, lamin B1, lamin B2 and the lamin A precursor, prelamin A, undergo canonical farnesylation and processing at CAAX motifs. In the case of prelamin A, there is an additional farnesylation-dependent endoproteolysis, which is defective in two congenital diseases: Hutchinson-Gilford progeria (HGPS) and restrictive dermopathy (RD). These two diseases arise respectively from defects in the prelamin A substrate and the enzyme (ZmpSte24) that processes it. Recent work has shed light on the roles of the lamin proteins and the enzymes involved in their farnesylation-dependent maturation. Other experimental work, including mouse model studies, have examined the possibility …

Dna Damage Responses In Progeroid Syndromes Arise From Defective Maturation Of Prelamin A, Michael Sinensky, Y. Liu, A. Rusinol, Y. Wang, Y. Zou

Faculty Publications, Biological Sciences

The genetic diseases Hutchinson-Gilford progeria syndrome (HGPS) and restrictive dermopathy (RD) arise from accumulation of farnesylated prelamin A because of defects in the lamin A maturation pathway. Both of these diseases exhibit symptoms that can be viewed as accelerated aging. The mechanism by which accumulation of farnesylated prelamin A leads to these accelerated aging phenotypes is not understood. Here we present evidence that in HGPS and RD fibroblasts, DNA damage checkpoints are persistently activated because of the compromise in genomic integrity. Inactivation of checkpoint kinases Ataxia-telangiectasia-mutated (ATM) and ATR (ATM- and Rad3-related) in these patient cells can partially overcome their …

Linking Ligand-Induced Alterations In Androgen Receptor Structure To Differential Gene Expression: A First Step In The Rational Design Of Selective Androgen Receptor Modulators, Dmitri Kazmin, Tatiana Prytkova, C. Edgar Cook, Russell Wolfinger, Tzu-Ming Chu, David Beratan, J. D. Norris, Ching-Yi Chang, Donald P. Mcdonnell

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We have previously identified a family of novel androgen receptor (AR) ligands that, upon binding, enable AR to adopt structures distinct from that observed in the presence of canonical agonists. In this report, we describe the use of these compounds to establish a relationship between AR structure and biological activity with a view to defining a rational approach with which to identify useful selective AR modulators. To this end, we used combinatorial peptide phage display coupled with molecular dynamic structure analysis to identify the surfaces on AR that are exposed specifically in the presence of selected AR ligands. Subsequently, we …

Never Let Me Clone? Countering An Ethical Argument Against The Reproductive Cloning Of Humans, Yvette Pearson

Philosophy Faculty Publications

In the March 2006 issue of EMBO reports, Christof Tannert, a bioethicist at the Max Delbrück Research Centre in Berlin, Germany, presented a moral argument against human reproductive cloning on the basis of Immanuel Kant’s categorical imperative (Tannert, 2006). In this article, I address some problems with Tannert’s views and show that our concerns about this prospective procedure should prompt us to scrutinize carefully the conventional procreative practices and attitudes. Indeed, if we set aside objections that are grounded in genetic determinism, many of the offensive features of human cloning are identical to problems with procreation by more conventional means, …

Analysis Of The Mouse And Human Acyl-Coa Thioesterase (Acot) Gene Clusters Shows That Convergent, Functional Evolution Results In A Reduced Number Of Human Peroxisomal Acots., Mary Hunt, Anna Rautanen, Maria Westin, Thomas Svensson, Stefan Alexson

Articles

The maintenance of cellular levels of free fatty acids and acyl-CoAs, the activated form of free fatty acids, is extremely important as imbalances in lipid metabolism have serious consequences for human health. Acyl-CoA thioesterases (ACOTs) hydrolyze acyl-CoAs to the free fatty acid and CoASH, and thereby have the potential to regulate intracellular levels of these compounds. We have previously identified and characterized a mouse ACOT gene cluster, comprised of six genes that apparently arose by gene duplications, encoding acyl- CoA thioesterases with localizations in cytosol (ACOT1), mitochondria (ACOT2) and peroxisomes (ACOT3-6). However, the corresponding human gene cluster contains only three …

2-Aminoethoxydiphenyl Borate As A Prototype Drug For A Group Of Structurally Related Calcium Channel Blockers In Human Platelets, Yuliya Dobrydneva, Christopher J. Abelt, Beth Dovel, Celina M. Thadigiri, Roy L. Williams, Peter F. Blackmore

Chemistry & Biochemistry Faculty Publications

We have synthesized a series of 2-aminoethoxydiphenyl borate (2-APB, 2,2-diphenyl-1,3,2-oxazaborolidine) analogs and tested their ability to inhibit thrombin-induced Ca²⁺ influx in human platelets. The analogs were either synthesized by adding various substituents to the oxazaborolidine ring (methyl, dimethyl, tert-butyl, phenyl, methyl phenyl, and pyridyl) or increasing the size of the oxazaborolidine ring to seven- and nine-membered rings. NMR analysis of the boron-containing analogs suggests that each of them exist as a ring structure through the formation of an N -> B coordinate bond (except for the hexyl analog). The possibility that these boron-containing compounds formed dimers was also …