Color properties and non-covalent interactions in hydrated (Z)-4-(1-cyano-2-(2,4,5-trimethoxyphenyl)-vinyl)pyridin-1-ium chloride salt: Insights from experimental and theoretical studies

The optical charge-transfer (CT) property and the crystal structure of (Z)-4-(1-cyano-2-(2,4,5-trimethoxyphenyl)vinyl)pyridin-1-ium chloride monohydrate salt (I), which belongs to an acrylonitrile family, was studied. The title salt, I, was characterized using different spectroscopy techniques and a single-crystal X-ray diffraction study combined with quantum chemical computations. The results showed that the color properties of I are determined by the CT, changes in bandgap, optical absorption, and various non-covalent interactions. The HOMO-LUMO energy gaps are 5.41 eV and 5.23 eV for the precursor and salt, respectively. It was demonstrated that π-π stacking interactions lead to the formation of intercalated dimers and donor-acceptor interactions assisted by hydrogen bonds; the dimers and interactions are different between the precursor and the salt. The cation moiety is mainly stabilized by N(1)+-H···Cl, and the anion is predominantly stabilized by strong O(1W)- H⋯ Cl- bonds as well as the hydrogen bonds with the MeO group O(2W)-H⋯O(1) and O(2W)-H⋯O(1W). The charge transfer between cation and anion moieties in the structure is established through NBO analysis.

Synthesis, structure, crystal growth and characterization of a novel semiorganic nonlinear optical l-proline lithium bromide monohydrate single crystal

l-Proline lithium bromide monohydrate (LPLBM), a promising semiorganic nonlinear optical material, was synthesized and single crystals of LPLBM were grown from solution by slow evaporation technique. Single crystal X-ray structure solution reveals that the grown crystal belongs to monoclinic system with space group P21. Presence of various functional groups was identified by FT-IR and FT-Raman spectral analyses. UV-Vis-NIR spectroscopic study shows that the LPLBM crystal possesses 90% of transmittance in the range of 250-1100nm. Vickers microhardness values, the dielectric constant and dielectric loss of the LPLBM crystal were reported. Elemental analysis by energy dispersive X-ray analysis shows the presence of carbon, nitrogen, oxygen and bromine. The surface morphology of the crystal was investigated using scanning electron microscopic study. The thermal stability of the LPLBM crystal was studied from TGA and DSC analysis. Second harmonic generation efficiency of the LPLBM crystal measured by Kurtz and Perry powder technique using Nd:YAG laser is about 0.3 times that of urea.

Crystal structure of catena-poly[[cadmium(II)-di-μ2-bromido-μ2-l-proline-κ(2) O:O'] monohydrate]

In the title coordination polymer, {[CdBr2(C5H9NO2)]·H2O} n , the Cd(II) ion is coordinated by four bromido ligands and two carboxyl-ate oxygen atoms of two symmetry-related proline ligands, which exist in a zwitterionic form, in a distorted octa-hedral geometry. There is an intra-molecular N-H⋯O hydrogen bond between the amino group and the carboxyl-ate fragment. Each coordinating ligand bridges two Cd(II) atoms, thus forming polymeric chains running along the c-axis direction. The water mol-ecules of crystallization serve as donors for the weak inter-molecular O-H⋯O and O-H⋯Br hydrogen bonds that link adjacent polymeric chains, thus forming a three-dimensional structure. N-H⋯O and N-H⋯Br hydrogen bonds also occur.

Crystal structure of 3-amino-1-propyl-pyridinium bromide

The title mol-ecular salt, C8H13N2 (+)·Br(-), crystallizes with two independent 3-amino-pyridinium cations and two bromide anions in the asymmetric unit (Z' = 2). In the pyridine ring, the N atom is alkyl-ated by a propyl group. The dihedral angle between the mean planes of the pyridinium ring and the propyl group is 84.84 (2)° in cation A, whereas the corresponding angle is 89.23 (2)° in cation B. In the crystal, the anions and cations are linked via N-H⋯Br and C-H⋯Br hydrogen bonds, forming chains propagating along [100].

4-Hy-droxy-1,2,6-tri-methyl-pyridinium chloride monohydrate

In the crystal of the title hydrated mol­ecular salt, C₈H₁₂NO⁺·Cl⁻·H₂O, the water mol­ecule makes two O—H⋯Cl hydrogen bonds, generating [010] zigzag chains of alternating water mol­ecules and chloride ions. The cation is bonded to the chain by an O—H⋯O hydrogen bond and two weak C—H⋯Cl inter­actions. Weak aromatic π–π stacking [centroid–centroid separation = 3.5175 (15) Å] occurs between the chains.

4-Hy-droxy-1,2,6-tri-methyl-pyridinium bromide monohydrate

The title salt, C₈H₁₂NO⁺·Br⁻·H₂O, is isomorphous with the chloride analogue [Seethalakshmi et al. (2013). Acta Cryst. E69, o835–o836]. In the solid state, the cations, anions and water mol­ecules are inter­linked by a network of O—H⋯O, O—H⋯Br and C—H⋯Br inter­actions. The water mol­ecule makes two O—H⋯Br hydrogen bonds, generating [010] zigzag chains of alternating water mol­ecules and bromide anions. The cation is involved in two inter­molecular C—H⋯Cl inter­actions in the chloride salt, whereas three inter­molecular C—H⋯Br inter­actions are observed in the title bromide salt. This additional inter­molecular C—H⋯Br inter­action links the adjacent water and bromide zigzag chains via cationic mol­ecules. In addition, weak π–π stacking inter­actions are observed between pyridinium rings [centroid–centroid distance = 3.5664 (13) Å].

1-Allyl-2-amino-pyridin-1-ium bromide

In the cation of the title salt, C₈H₁₁N₂⁺·Br⁻, the dihedral angle between the planes of the pyridinium ring and the allyl group is 79.4 (3)°. In the crystal, N—H⋯Br and weak C—H⋯Br hydrogen bonds link the cations and anions, forming chains of alternating R₂¹(7) and R₄²(8) rings, which run parallel to the c-axis direction. The crystal studied was an inversion twin with components in a 0.753 (12):0.247 (12) ratio.

catena-Poly[[[aqua-(glycine-κO)lithium]-μ-glycine-κ(2) O:O'] bromide]

In the title coordination polymer, {[Li(C₂H₅NO₂)₂(H₂O)]Br}_n, the Li⁺ cation is coordinated by three carboxyl­ate O atoms of zwitterionic glycine mol­ecules and by a water mol­ecule, forming a distorted tetra­hedral geometry. One of the two glycine mol­ecules bridges neighbouring complexes, forming an infinite chain parallel to the c axis. Polymeric chains are further linked by extensive hydrogen bonds involving the Br⁻ anions and glycine and water mol­ecules, producing a three-dimensional network.

Glycine-phthalic acid (1/1)

In the title compound, C₂H₅NO₂·C₈H₆O₄, the glycine mol­ecule exists as a zwitterion (2-aza­niumyl­ethano­ate) with a positively charged amino group and a negatively charged carboxyl­ate group. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link the components into layers parallel to the ab plane. The central part of each layer is composed of hydrogen-bonded glycine zwitterions, while phthalic acid mol­ecules inter­act with the zwitterions in such a way that benzene rings protrude up and down from the layer.

Crystallographic and modelling studies on Mycobacterium tuberculosis RuvA Additional role of RuvB-binding domain and inter species variability

RuvA, along with RuvB, is involved in branch migration of heteroduplex DNA in homologous recombination. The structures of three new crystal forms of RuvA from Mycobacterium tuberculosis (MtRuvA) have been determined. The RuvB-binding domain is cleaved off in one of them. Detailed models of the complexes of octameric RuvA from different species with the Holliday junction have also been constructed. A thorough examination of the structures presented here and those reported earlier brings to light the hitherto unappreciated role of the RuvB-binding domain in determining inter-domain orientation and oligomerization. These structures also permit an exploration of the interspecies variability of structural features such as oligomerization and the conformation of the loop that carries the acidic pin, in terms of amino acid substitutions. These models emphasize the additional role of the RuvB-binding domain in Holliday junction binding. This role along with its role in oligomerization could have important biological implications.

X-ray studies of crystalline complexes involving amino acids and peptides. XLIV. Invariant features of supramolecular association and chiral effects in the complexes of arginine and lysine with tartaric acid

The tartaric acid complexes with arginine and lysine exhibit two stoichiometries depending upon the ionization state of the anion. The structures reported here are DL-argininium DL-hydrogen tartrate, bis(L-argininium) L-tartrate, bis(DL-lysinium) DL-tartrate monohydrate, L-lysinium D-hydrogen tartrate and L-lysinium L-hydrogen tartrate. During crystallization, L-lysine preferentially interacts with D-tartaric acid to form a complex when DL-tartaric acid is used in the experiment. The anions and the cations aggregate into separate alternating layers in four of the five complexes. In bis(L-argininium) L-tartrate, the amino acid layers are interconnected by individual tartrate ions which do not interact among themselves. The aggregation of argininium ions in the DL- and the L-arginine complexes is remarkably similar, which is in turn similar to those observed in other dicarboxylic acid complexes of arginine. Thus, argininium ions have a tendency to assume similar patterns of aggregation, which are largely unaffected by a change in the chemistry of partner molecules such as the introduction of hydroxyl groups or a change in chirality or stoichiometry. On the contrary, the lysinium ions exhibit fundamentally different aggregation patterns in the DL–DL complexes on the one hand and L–D and L–L complexes on the other. Interestingly, the pattern in the L–D complex is similar to that in the L–L complex. The lysinium ions in the DL–DL complex exhibit an aggregation pattern similar to those observed in the DL-lysine complexes involving other dicarboxylic acids. Thus, the effect of change in the chirality of a subset of the component complexes could be profound or marginal, in an unpredictable manner. The relevant crystal structures appear to indicate that the preference of L-lysine for D-tartaric acid is perhaps caused by chiral discrimination resulting from the amplification of a small energy difference.

Structure of Mycobacterium tuberculosis RuvA, a protein involved in recombination

The process of recombinational repair is crucial for maintaining genomic integrity and generating biological diversity. In association with RuvB and RuvC, RuvA plays a central role in processing and resolving Holliday junctions, which are a critical intermediate in homologous recombination. Here, the cloning, purification and structure determination of the RuvA protein from Mycobacterium tuberculosis (MtRuvA) are reported. Analysis of the structure and comparison with other known RuvA proteins reveal an octameric state with conserved subunit-subunit interaction surfaces, indicating the requirement of octamer formation for biological activity. A detailed analysis of plasticity in the RuvA molecules has led to insights into the invariant and variable regions, thus providing a framework for understanding regional flexibility in various aspects of RuvA function.

X-ray studies of crystalline complexes involving amino acids and peptides. XLIII. Adipic acid complexes of L- and DL-lysine

The asymmetric unit of the DL-lysine complex of adipic acid [bis(DL-lysinium) adipate], 2C6H15N2O2+.C6H8O(4)2-, contains a zwitterionic singly charged lysinium cation and half a doubly charged adipate anion (the complete anion has inversion symmetry). That of the L-lysine complex (lysinium hydrogen adipate), C6H15N2O2+.C6H9O4-, consists of a lysinium cation and a singly charged hydrogen adipate anion. In both structures, the lysinium cations organize into layers interconnected by adipate or hydrogen adipate anions. However, the arrangement of the molecular ions in the layer is profoundly different in the DL- and L-lysine complexes. The hydrogen adipate anions in the L-lysine complex form linear arrays in which adjacent ions are interconnected by a symmetric O...H...O hydrogen bond.

2'-(4-Fluorophenyl)-[1,2,3]triazolo[4',5':16,17]androst-5-en-3beta-ol methanol hemisolvate

The asymmetric unit of the title compound, C(25)H(30)FN(3)O.0.5CH(3)OH, contains four symmetry-independent steroid and two methanol molecules. The conformations of the independent steroid molecules are very similar. Intermolecular O-H.O hydrogen bonds create two independent chains, each of which links two of the independent steroid molecules plus one methanol molecule via a co-operative O-H.O-H.O-H pattern. Intermolecular C-H.O and C-H.F interactions are also observed.

16-Cyano-13α-(5-methyl-1,3,4-oxadiazol-2-yl)-13,16-seco-17-norandrost-5-en-3β-yl acetate

In the title compound, C(23)H(31)N(3)O(3), the outer cyclohexane rings have chair conformations, while the central cyclohexene ring adopts a half-chair conformation. In the solid state, intra- and intermolecular C-H.N interactions are observed.

An aza-steroidal [17,16-c]pyrazole derivative: 2'-(p-fluorophenyl)-17a-aza-2'H-pyrazolo[4',3':16,17]-D-homoandrost-4-en-3-one

The asymmetric unit of the title compound, C(26)H(30)FN(3)O, contains two crystallographically independent molecules, the core skeletons of which have the same absolute configuration and almost identical conformations, except for differences in the orientation of the p-fluorophenyl ring. The tetrahydropyridine ring adopts a half-chair conformation, while the cyclohexenone ring has a slightly distorted envelope conformation. The cyclohexane rings have chair conformations, sometimes slightly distorted. Intermolecular N-H.O, N-H.N and C-H.F interactions and an intramolecular C-H.N interaction are observed.

16-(4-Isopropylbenzylidene)androst-4-ene-3,17-dione

In the title compound, C(29)H(36)O(2), the outer cyclohexene ring of the steroid nucleus has a conformation that lies about half-way between a half-chair and an envelope, while the central and outer cyclohexane rings of the steroid nucleus have slightly distorted chair conformations. The steroidal cyclopentane ring adopts a 13beta,14alpha-half-chair conformation. The benzylidene moiety has an E configuration with respect to the carbonyl group on the cyclopentane ring. The dihedral angle between the mean planes of the steroid nucleus and the benzylidene moiety is 35.54 (9) degrees. The packing of the molecules is assumed to be dictated mainly by weak intermolecular C-H.O interactions.

Two androst-5-ene derivatives: 16-[4-(3-chloropropoxy)-3-methoxybenzylidene]-17-oxoandrost-5-en-3 beta-ol and 16-[3-methoxy-4-(2-pyrrolidin-1-ylethoxy)benzylidene]-3 beta-pyrrolidinoandrost-5-en-17 beta-ol monohydrate

In the steroidal nucleus of 16-[4-(3-chloropropoxy)-3-methoxybenzylidene]-17-oxoandrost-5-en-3 beta-ol, C(30)H(29)ClO(4), (I), the outer two six-membered rings are in chair conformations, while the five-membered ring and the central six-membered ring of the steroidal nucleus adopt half-chair and envelope conformations, respectively. In 16-[3-methoxy-4-(2-pyrrolidin-1-ylethoxy)benzylidene]-3 beta-pyrrolidinoandrost-5-en-17 beta-ol monohydrate, C(37)H(54)N(2)O(3).H(2)O, (II), one C atom of one of the outer six-membered rings of the steroid nucleus and the four C atoms of the ethoxypyrrolidine ring are disordered over two sites. The five-membered ring, and the central and one of the outer six-membered rings of the steroidal nucleus exhibit distorted half-chair, chair and envelope conformations, respectively. In (I), intermolecular O-H...O hydrogen bonds link the molecules into chains via a co-operative O-H...O-H...O-H pattern. In (II), intermolecular O-H...O and O-H...N hydrogen bonds link the steroid and water molecules alternately into extended chains.

Two azasteroidal [3,2-c]pyrazole derivatives: 2′-(p-fluorophenyl)-4-azapyrazolo[4′,3′:2,3]-5α-androstan-17β-yl acetate and 2′-(p-fluorophenyl)-4-azapyrazolo[4′,3′:2,3]-5α-androstan-17β-ol

In both the title aza-steroids, 2'-(p-fluorophenyl)-4-azapyrazolo[4',3':2,3]-5alpha-androstan-17beta-yl acetate, C(27)H(34)FN(3)O(2), (I), and 2'-(p-fluorophenyl)-4-azapyrazolo[4',3':2,3]-5alpha-androstan-17beta-ol, C(25)H(32)FN(3)O, (II), the tetrahydropyridine ring adopts a half-chair conformation and is considerably strained as a consequence of the presence of the fused planar pyrazole ring. In both compounds, both cyclohexane rings have chair conformations, while the cyclopentane ring has an envelope conformation. All the rings of the steroid nucleus are trans fused. In (I), intermolecular N-H.O, C-H.F, C-H.O and C-H.N interactions are observed in the solid state, while intermolecular N-H.O and O-H.N hydrogen bonds are observed in (II).

1-[2-(4-nitrophenoxy)acetyl]pyrrolidin-2-one: an antiamnesic agent

The title compound, C(12)H(12)N(2)O(5), is a potential antiamnesic agent. The pyrrolidinone ring has an envelope conformation, and the central moiety is almost coplanar with the planes of the phenyl and pyrrolidinone rings. In the crystal structure, weak intermolecular C--H...O interactions link the molecules into a complex network that can be described by R(2)(2)(X) rings (X = 16, 20 and 26) and a C(12) chain.

2-(2-Naphthyloxy)acetate derivatives. II. A new class of antiamnesic agents

The title compounds, 4-(2-naphthyloxymethylcarbonyl)morpholine, C(16)H(17)NO(3), (I), and 4-methyl-1-(2-naphthyloxymethylcarbonyl)piperazine, C(17)H(20)N(2)O(2), (II), are potential antiamnesics. The morpholine ring in (I) and the piperazine ring in (II) adopt chair conformations. In (I), the molecules are linked by weak intermolecular C-H.O interactions into chains that have a graph-set motif of C(10), while in (II), the molecules are linked by weak intermolecular C-H.O interactions that generate two C(7) graph-set motifs. The dihedral angle between the naphthalene moiety and the best plane through the morpholine ring is 20.62 (4) degrees in (I), while the naphthalene moiety is oriented nearly perpendicular to the mean plane of the piperazine ring in (II).

2-(2-Naphthyloxy)acetate derivatives. I. A new class of antiamnesic agents

The title compounds 1-(2-naphthyloxymethylcarbonyl)piperidine, C(17)H(19)NO(2), (I), and 3-methyl-1-(2-naphthyloxymethylcarbonyl)piperidine, C(18)H(21)NO(2), (II), are potential antiamnesics. In (II), the methyl-substituted piperidine ring is disordered over two conformations. The piperidine ring has a chair conformation in both compounds. In (I), the molecules are linked by weak intermolecular C-H.O interactions to give networks represented by C(4), C(6) and R(4)(4)(18) graph-set motifs, while in (II), weak intermolecular C-H.O interactions generate R(1)(2)(5), C(4) and C(7) graph-set motifs. The dihedral angle between the naphthalene moiety and the piperidine ring is 33.83 (7) degrees in (I), while it is 31.78 (11) and 19.38 (19) degrees for the major and minor conformations, respectively, in (II).

Hydrogen-bonded dimers of 1,8,10-trihydroxy-10-(prop-2-enyl)anthracen-9(10H)-one: S(6), R(2)(1)(10) and R(2)(2)(14) motifs

The central ring of the anthrone system in the title compound, C(17)H(14)O(4), has a shallow envelope conformation, and each of the two outer rings is inclined at an angle of 17.41 (3) degrees. In the solid state, the molecules exist as centrosymmetrically related O-H.O hydrogen-bonded dimers. Two intramolecular O-H.O hydrogen bonds, involving the central carbonyl O atom and having a graph-set motif of S(6), are observed. These intramolecular interactions lead co-operatively to an O-H.O.H-O pattern that has a binary graph-set motif of R(2)(1)(10).

16-(4-Cyanobenzylidene)-17-oxoandrost-5-en-3beta-ol

In the title compound, 4-(3beta-hydroxy-17-oxoandrost-5-en-16-ylidenemethyl)benzonitrile, C(27)H(31)NO(2), rings A and C of the steroid nucleus are in chair conformations. The central six-membered ring B is in an 8beta,9alpha-half-chair conformation, while the five-membered ring D adopts a 13beta,14alpha-half-chair conformation. The cyanobenzylidene moiety has an E configuration with respect to the carbonyl group at position C17. The dihedral angle between the planes of the steroid nucleus and the cyanobenzylidene moiety is 22.61 (15) degrees. Intermolecular O-H.N hydrogen bonds formed between the hydroxyl group of the steroid and the N atom of the cyanobenzylidene moiety of symmetry-related molecules link the steroid molecules into chains which run parallel to the b axis.

16-[3-Methoxy-4-(2-piperidin-1-ylethoxy)benzylidene]-17-oxoandrost-5-en-3beta-yl acetate monohydrate

The title compound, C(36)H(49)NO(5).H(2)O, has the outer two six-membered rings of the steroid nucleus in chair conformations. The central ring B of the steroid nucleus is in an 8beta,9alpha-half-chair conformation, while ring D of the steroid adopts a slightly distorted 13beta,14alpha-half-chair conformation. The piperidine ring is in a chair conformation. The methoxybenzylidene moiety has an E configuration with respect to the carbonyl group at position 17. Intermolecular O-H.O and O-H.N hydrogen bonds link the steroid and water molecules into chains which run parallel to the b axis.

3Beta-(1-allyl-1-pyrrolidinio)-16-(2-pyridylmethylene)androst-5-en-17beta-ol bromide hemihydrate

The title compound, C(32)H(45)N(2)O(+).Br(-).0.5H(2)O, has the outer two six-membered rings in chair conformations, while the central ring is in an 8beta,9alpha-half-chair conformation. The five-membered ring of the steroid nucleus adopts a slightly deformed 14alpha-envelope conformation. The pyridylmethylene moiety has an E configuration with respect to the hydroxyl group at position 17. The structure is stabilized by a network of O-H...Br-type intermolecular hydrogen bonds.

16-(4-Cyanobenzylidene)-3 beta-pyrrolidinoandrost-5-en-17 beta-ol monohydrate

In the title compound, C(31)H(40)N(2)O x H(2)O, the outer two six-membered rings are in chair conformations, while the central ring is in an 8 beta,9 alpha-half-chair conformation. The five-membered ring adopts a 13 beta-envelope conformation and the cyanobenzylidene moiety has an E configuration with respect to the hydroxyl group at position 17. The steroid nuclei are linked by intermolecular O[bond]H...O and O[bond]H...N hydrogen bonds to form a molecular network. The molecular packing has an interesting feature, with the steroids aligned parallel to the b axis, forming a closed loop through hydrogen bonds linked via water molecules.

Demonstration of direct effects of growth hormone on neonatal cardiomyocytes

The cellular and molecular basis of growth hormone (GH) actions on the heart remain poorly defined, and it is unclear whether GH effects on the myocardium are direct or mediated at least in part via insulin-like growth factor (IGF-1). Here, we demonstrate that the cultured neonatal cardiomyocyte is not an appropriate model to study the effects of GH because of artifactual loss of GH receptors (GHRs). To circumvent this problem, rat neonatal cardiomyocytes were infected with a recombinant adenovirus expressing the murine GHR. Functional integrity of GHR was suggested by GH-induced activation of the cognate JAK2/STAT5, MAPK, and Akt intracellular pathways in the cells expressing GHR. Although exposure to GH resulted in a significant increase in the size of the cardiomyocyte and increased expression of c-fos, myosin light chain 2, and skeletal alpha-actin mRNAs, there were no significant changes in IGF-1 or atrial natriuretic factor mRNA levels in response to GH stimulation. In this model, GH increased incorporation of leucine, uptake of palmitic acid, and abundance of fatty acid transport protein mRNA. In contrast, GH decreased uptake of 2-deoxy-d-glucose and levels of Glut1 protein. Thus, in isolated rat neonatal cardiomyocytes expressing GHR, GH induces hypertrophy and causes alterations in cellular metabolic profile in the absence of demonstrable changes in IGF-1 mRNA, suggesting that these effects may be independent of IGF-1.

Effect of development and hypoxic-ischemia upon rabbit brain glucose transporter expression

We have cloned and sequenced a full length rabbit GLUT 1 and partial rabbit GLUT 3 cDNAs. The derived rabbit GLUT 3 peptide revealed 84% homology to the mouse, 82% to the rat, human, dog, and sheep, and 69% to the chicken GLUT 3 peptides. Using Northern blot analysis, we investigated the tissue and brain cellular distribution of GLUT 1 and GLUT 3 expression. In addition, we examined the effect of development and hypoxic-ischemia upon brain GLUT 1 and GLUT 3 mRNA levels. While GLUT 1 mRNA was observed in most tissues, GLUT 3 was expressed predominantly in the brain, placenta, stomach, and lung with minor amounts in the heart, kidney and skeletal muscle. In the brain, both GLUT 1 and GLUT 3 were noted in neuron- and glial-enriched cultures. Both GLUT 1 and GLUT 3 mRNA levels demonstrated a similar developmental progression (p<0.05) secondary to post-transcriptional mechanisms. Further, while hypoxic-ischemia did not significantly affect brain GLUT 1 mRNA and protein, it altered GLUT 3 mRNA levels in a region-specific manner, with a three-fold increase in the cerebral cortex, a two-fold increase in the hippocampus, and a 50% increase in the caudate nucleus (p<0.05). We conclude, that the rabbit GLUT 3 peptide sequence exhibits 82-84% homology to that of other species in the coding region with a 62-89% sequence identity in the 3'-untranslated region. The tissue-specific expression of rabbit GLUT 3 mimics that of the human closely. Postnatal development and hypoxic-ischemia with reperfusion injury cause an increase in brain GLUT 3 expression, as a response to synaptogenesis and substrate deprivation, respectively.

Sp1 and Sp3 regulate transcriptional activity of the facilitative glucose transporter isoform-3 gene in mammalian neuroblasts and trophoblasts

The murine facilitative glucose transporter isoform 3 (Glut 3) is developmentally regulated and is predominantly expressed in neurons and trophoblasts. Employing the primer extension and RNase protection assays, the transcription start site (denoted as +1) of the murine Glut 3 gene was localized to 305 base pairs (bp) 5' to the ATG translation start codon. Transient transfection assays in N2A, H19-7 neuroblasts, and HRP.1 trophoblasts using sequential 5'-deletions of the murine Glut 3-luciferase fusion gene indicated that the -203 to +237 bp region with reference to the transcriptional start site contained promoter activity. Repressor function was limited to the -137 to -130 bp region within the transcriptional activation domain. The nuclear factors Sp1 and Sp3 bound this GC-rich region in N2A, H19-7, and HRP.1 cells. Dephosphorylation of Sp1 was essential for Glut 3 DNA binding. The related Sp3 protein also bound this same region of mouse Glut 3 in all three cell lines. Mutations of the Sp1-binding site employed in transient transfection and mobility shift assays confirmed the nature of the DNA-binding proteins, while supershift assays with anti-Sp1 and anti-Sp3 IgGs characterized the differences in the two DNA-binding proteins. Co-transfection of the Glut 3-luciferase fusion gene with or without mutations of the Sp1-binding site along with the Sp1 or Sp3 expression vectors in Drosophila SL2 cells confirmed a reciprocal effect, with Sp1 suppressing and Sp3 activating Glut 3 gene transcription.