Management of high-quality dehydrated grape in vinification to produce dry red wines.

Grape controlled dehydration of "Cesanese" and "Sangiovese" wine grapes, followed by an innovative vinification protocol, was studied. Fresh grapes of both varieties were processed into basic wines (IW = initial wine). 'Cesanese' must from pressed dehydrated grapes (solid and liquid) was directly added (15 and 30% v/v) into the IW activating a refermentation. 'Sangiovese' must (solid and liquid) from pressed dehydrated grapes was fermented and, when the wine reached 5% alcohol concentration, every day, the IW was added until a final concentration of 40 or 60% (v/v). The produced "blended wines" (BW) had significantly higher alcohol, glycerol, extract, and polyphenol concentration. Malolactic fermentation was completely ended in all BW with no malic acid and formation of lactic acid (0.5-1 g/L). All wines showed a significant higher concentration in 4-vinylguaiacol, acetovanillone, and 3-oxo-α-ionol, providing spicy and fruity notes at the sensory analyses, and being appreciated for their body balance, less acidity, and flavor intensity.

Reduced interleukin-2 responsiveness impairs the ability of Treg cells to compete for IL-2 in nonobese diabetic mice.

Enhancement of regulatory T cell (Treg cell) frequency and function is the goal of many therapeutic strategies aimed at treating type 1 diabetes (T1D). The interleukin-2 (IL-2) pathway, which has been strongly implicated in T1D susceptibility in both humans and mice, is a master regulator of Treg cell homeostasis and function. We investigated how IL-2 pathway defects impact Treg cells in T1D-susceptible nonobese diabetic (NOD) mice in comparison with protected C57BL/6 and NOD congenic mice. NOD Treg cells were reduced in frequency specifically in the lymph nodes and expressed lower levels of CD25 and CD39/CD73 immunosuppressive molecules. In the spleen and blood, Treg cell frequency was preserved through expansion of CD25(low), effector phenotype Treg cells. Reduced CD25 expression led to decreased IL-2 signaling in NOD Treg cells. In vivo, treatment with IL-2-anti-IL-2 antibody complexes led to effective upregulation of suppressive molecules on NOD Treg cells in the spleen and blood, but had reduced efficacy on lymph node Treg cells. In contrast, NOD CD8(+) and CD4(+) effector T cells were not impaired in their response to IL-2 therapy. We conclude that NOD Treg cells have an impaired responsiveness to IL-2 that reduces their ability to compete for a limited supply of IL-2.

Endogenous erythropoietin and a single bolus of 40,000 IU of epoetin alpha do not protect the heart from ischaemia-reperfusion injury during extracorporeal circulation for cardiac surgery.

Erythropoietin (EPO) exerts a tissue-protective activity in several non-haematopoietic tissues such as heart, brain, spinal cord and muscle. We evaluated the relationship between pre-operative endogenous EPO blood levels and myocardial damage in patients undergoing cardiopulmonary bypass (CPB). Furthermore, we investigated whether pre-operative administration of a single bolus of 40,000 IU epoetin alpha (EPOalpha) would reduce troponin I or creatine kinase isoenzyme (CK-MB) after on-pump coronary artery bypass graft (CABG) surgery. Sixty-seven patients (45 CABG, 22 valvular surgery) were enrolled. EPO was measured in the pre-surgical period and correlated to post-surgical troponin I and CK-MB peaks. Subsequently, forty patients scheduled for CABG were randomized into two groups, receiving, respectively, a) standard medical and surgical treatment (20 patients) and b) the same treatment plus 40,000 IU of EPOalpha in a single bolus injection in the immediate pre-surgical period (20 patients). In our population, we did not find any correlation between pre-surgical EPO and post-surgical troponin I or CK-MB peaks (p Pearson > 0.05). Furthermore, patients treated with EPOalpha did not show differences compared to the control group in either troponin I (1.7+/-1.8 vs 2.6+/-3.4, p>0.05) or CK-MB (19.6 +/-13.2 vs 17.1+/-12.6, p>0.05) peaks measured in the post-surgical period.

Effect of omapatrilat on the aging process of the normal rat.

Previous results have shown that inhibition of the renin-angiotensin system (RAS) either with an angiotensin II (Ang II), type 1 receptor blocker (losartan) or with an angiotensin converting enzyme inhibitor (ACEI, enalapril) has a protective effect on cardiovascular, renal, hepatic and cerebral structure and function during aging. The present study has analyzed the effect of chronic administration of a newly developed compound, omapatrilat, on clinical, histological and biochemical changes due to aging. Omapatrilat combines the action of an ACEI and of an inhibitor of a neutral endopeptidase involved in the metabolism of the atrial natriuretic peptide. The final effect is a decrease of a vasoconstrictor and proinflammatory mechanism like the RAS and the potentiation of two vasodilating compounds like bradykinin and the atrial natriuretic peptide. Based on these actions, its protective effect might be greater than formerly used pharmacological agents. Determinations have been performed on young adults (6 months old), adults (12 months old) or senile (18 months old) rats. Omapatrilat (35 mg/kg/day during 6 months and 20 mg/kg/day thereafter) was administered in the drinking water since weaning until sacrifice. Cardiovascular, renal, and cerebral structure as well as cognitive behavior, cardiovascular and renal function has been analyzed. The biochemical analysis has also established whether the beneficial action of Ang II inhibition is related to an increased activity of the nitric oxide synthase as observed in previous studies. Moreover, this study has tried to determine the relationship between the protective effect of these drugs and the levels of antioxidant defenses present in the blood and/or in the tissues. Hence, enzymatic and non-enzymatic antioxidants have been evaluated.

[N,N'-(4-Methyl-4-azaheptane-1,7-diyl-kappaN)bis(4-methoxysalicylideniminato-kappa4O,N,N',O')]cobalt(II) ethanol hemisolvate.

The title compound, [Co(C(23)H(29)N(3)O(4))].0.5C(2)H(6)O or [Co(II)[(4-MeO-sal)(2)Medpt]].0.5CH(3)CH(2)OH [(4-MeO-sal)(2)Medpt is N,N'-(4-methyl-4-azaheptane-1,7-diyl)bis(4-methoxysalicylideniminate)], obtained through the reaction of H(2)[(4-MeO-sal)(2)Medpt] and Co(CH(3)COO)(2) in refluxing ethanol under an atmosphere of ultrapure nitrogen, has the usual pseudo-trigonal-bipyramidal coordination arrangement previously found for this class of (sal)(2)Rdpt compounds. The O-Co-O bond angle [120.4 (1) degrees] is significantly smaller than the corresponding values previously found for most non-O(2)-bound [Co(II)[(sal)(2)Medpt]]-type molecules (observed range 126.9-138.6 degrees), whereas the equatorial Co-N bond [2.185 (3) A] is relatively long.

trans-Dichlorotetrakis(4-methylpyrimidine-N1)ruthenium(II).

The title compound, trans-[Ru(II)Cl(2)(N(1)-mepym)(4)] (mepym is 4-methylpyrimidine, C(5)H(6)N(2)), obtained from the reaction of trans,cis,cis-[Ru(II)Cl(2)(N(1)-mepym)(2)(SbPh(3))(2)] (Ph is phenyl) with excess mepym in ethanol, has fourfold crystallographic symmetry and has the four pyrimidine bases coordinated through N(1) and arranged in a propeller-like orientation. The Ru-N and Ru-Cl bond distances are 2.082 (2) and 2.400 (4) A, respectively. The methyl group, and the N(3) and Cl atoms are involved in intermolecular C-H...N and C-H...Cl hydrogen-bond interactions.

Dissolution of calcium pyrophosphate crystals by polyphosphates: an in vitro and ex vivo study.

OBJECTIVE: To determine the dissolving ability (DA) of linear pentasodium tripolyphosphate (PSTP), cyclic trisodium metaphosphate (TSMP), polymeric sodium metaphosphate (SMP) on synthetic crystals of calcium pyrophosphate dihydrate (CPPD) and on crystalline aggregates of menisci from patients with chondrocalcinosis (CC). METHODS: Synthetic CPPD crystals were mixed with phosphate buffered saline (PBS), which contained the different polyphosphates, for one hour at 37 degrees C. The calcified menisci were obtained from the knees of four female patients with CPPD disease who underwent total arthroscopic meniscectomy for degenerative meniscal lesions. Meniscal cryosections and fragments were incubated in SMP (15 mg/ml PBS) at 37 degrees C for one hour and 24 hours, respectively. Histological evaluation on meniscal samples after polyphosphate incubation was carried out by ordinary transmitted light microscopy and polarised light microscopy. The dissolution of CPPD crystals by polyphosphates was assessed by atomic absorption spectroscopy, which determined the amount of calcium liberated from synthetic crystals and meniscal fragments. Cytotoxicity of SMP was evaluated by tetrazolium salt assay and by an ultrastructural study on cultured chondrocytes. RESULTS: SMP and PSTP showed higher DA on CPPD crystals than TSMP. Analysis of the DA values at increasing concentrations of SMP showed that a concentration of 15 mg/ml completely dissolved 2.0 mg CPPD crystals. The solution of meniscal CPPD crystals showed a significant increase of calcium concentration after three hours and 24 hours of SMP incubation (p=0.0001; Kruskal-Wallis analysis of variance) compared with fragments incubated in PBS control solution. Macroscopic and microscopic evaluation of meniscal specimens showed a notable reduction of CPPD deposits. A 50% inhibitory dose on cultured chondrocytes was reached at the maximum concentration of SMP used in this work (15 mg/ml); ultrastructural analysis did not show morphological alterations in the treated cells. CONCLUSION: The results of this study indicate that linear polyphosphates are effective in dissolving both synthetic and ex vivo CPPD crystal aggregates. This suggests a potential therapeutic use for these molecules in the treatment of symptomatic CC.

Density functional geometry optimization and energy calculations of calcium(II)-triphosphate complexes. Polyphosphates as possible dissolving agents for calcium pyrophosphate dihydrate crystals in chondrocalcinosis disease.

Geometry optimizations and energy calculations have been carried out via molecular orbital methods at the density functional B3LYP/LANL2DZ level on the molecules PO3-, OPO3(3-), HOPO3(2-), CH3OPO3(2-), H(CH3OPO3)-, O(PO3)2(4-), HO(PO3)2(3-), CH2(PO3)2(4-), (CH3OPO2)O(PO3)3-, O(PO3)3(5-), HO(PO3)3(4-), (PO3)3(3-), (CH3OPO2)O(PO3)2(4-), [Mg[O(PO3)2)]]2-, [Ca[O(PO3)2]]2-, [Ca[CH2(PO3)2]]2-, [Ca[CH3OPO2)O(PO3)]]-, [Ca(PO3)3]-, [Ca[O(PO3)3]]3-, and [Ca[CH3OPO2)O(PO3)2]]2- with the aim to find reliable and easily accessible computational methods to simulate some phosphate-containing molecules of importance for the living cells and to study the energetics for protonation and metal-complex formation reactions. The analysis is part of a general investigation on phosphate-containing molecules as potential dissolving agents for calcium pyrophosphate dihydrate (CPPD) crystals which deposit in certain articular diseases. The basis set was expanded to 6-31G** for the P atoms for all the molecules investigated and to 6-31G* for the O atoms for OPO3(3-). Calculations at the semiempirical MNDO/d level were also carried out for comparison purposes on the free ligand molecules and on [Mg[O(PO3)2]]2-. The density functional analysis reproduced well the geometry found at the solid state via X-ray diffraction. The analyses of the geometrical parameters and the total electronic energy of the molecules shows that O(PO3)2(4-) and other di- and tri-phosphates are versatile ligands for divalent metal ions like Ca2+. The computed P-O-P bond angle for free O(PO3)2(4-) is 180 degrees and the conformation of the two PO3- groupings is staggered along the P...P vector. The linear arrangement for P-O-P is assisted by P-O pi interactions. The bending of the P-O-P angle when accompanied by a slight P-O(b) elongation requires a very small amount of energy; 4.65 kcal/mol to pass from 180 to 140 degrees , as calculated at the DFT level. The computed Ca-O and Mg-O bond distances for [M[O(PO3)2]]2- are 2.378 and 2.079A, when the metal ions link two oxygen atoms from each PO3 group. The computed Ca-O bond lengths for [Ca[CH3OPO2)O(PO3)]]- are 2.482 (PalphaO2) and 2.358A (PbetaO2), showing a significant lengthening for Ca-OPalpha, when compared to the pyrophosphate derivative. The Ca-O bond lengths for [Ca[O(PO3)3]]3- and [Ca[CH3OPO2)O(PO3)2]]2- are 2.251A and 2.525 (PalphaO2), 2.407 and 2.338 (PbetaO2), and 2.251 and 2.228A (PgammaO2), showing a shortening for the Ca-OPgamma bond upon methylation. The (Pbeta)O-Pgamma bond length increases significantly (0.09 A) upon Ca(II) coordination to (CH3OPO2)O(PO3)2(4-) via all the three PO3 groups. This latter result suggests that metal complexes of linear organic-triphosphates have a larger tendency to release the PgammaO3 group when compared to the free ligand molecules. The electronic contribution to the energy of the complex formation reaction for [Ca[CH2(PO3)2]]2- is only slightly higher (some 1.8 kcal) than that for [Ca[O(PO3)2]]2-; but is much higher (some 63 kcal) than that relevant to the formation of [Ca[CH3OPO2)O(PO3)2]]2-. (ABSTRACT TRUNCATED)

Reoperative coronary surgery with and without cardiopulmonary bypass.

BACKGROUND: Reoperative coronary surgery without cardiopulmonary bypass (CPB) was analyzed to evaluate the technical profile of the patients studied and the benefit from this technique. MATERIAL AND METHODS: From November 21, 1994 to May 20, 1999, 166 patients had reoperative coronary surgery, 112 patients (Group A) with and 54 patients (Group B) without CPB. Median sternotomy was used in all the patients in Group A and in 13 patients in Group B. The remaining had a LAST (37 patients) or a posterolateral thoracotomy (4 patients). RESULTS: Anastomoses per patient were 2.4 +/- 0.8 in Group A and 1.1 +/- 0.4 in Group B (p < 0.001). When a single graft was needed, CPB was not used in 82.8% of the cases. However, when more than one graft was required, CPB was not used in only 5.6% of the cases. When a single territory had to be grafted, CPB was not used in 76.6% of the patients. If two territories were grafted, only 6.8% of the patients were in Group B, whereas no patient who needed a graft in all the three territories was in Group B. Overall mortality was 3.6% cerebrovascular accident (CVA) and acute myocardial infarction (AMI) incidence were 0.6% and 1.8%, respectively, and were similar in both groups. Incidence of early major events (overall 8.4%) was not different between groups. CONCLUSIONS: The primary endpoints (mortality, CVA rate, and AMI) were similar in both groups, but patients in Group B were less complicated. However, patients in the two groups were not the same, as the technical profile was quite different. As our results were similar to those obtained in the first operation, we think that consideration of different surgical possibilities, depending on territory to be grafted, will improve the results of redo coronary surgery, making them similar to those obtained in the first operation.

Molecular orbital study of complexes of zinc(II) with sulphide, thiomethanolate, thiomethanol, dimethylthioether, thiophenolate, formiate, acetate, carbonate, hydrogen carbonate, iminomethane and imidazole. Relationships with structural and catalytic zinc in some metallo-enzymes.

Geometry optimization and energy calculations have been performed at the density functional B3LYP/LANL2DZ level on hydrogen sulfide (HS-), dihydrogensulfide (H2S), thiomethanolate (CH3S-), thiomethanol (CH3SH), thiophenolate (C6H5S-), methoxyde (CH3O-), methanol (CH3OH), formiate (HCOO-), acetate (CH3COO-), carbonate (CO3(2-)), hydrogen carbonate (HCO3-), iminomethane (NH=CH2), [ZnS], [ZnS2]2-, [Zn(HS)]+, [Zn(H2S)]2+, [Zn(HS)4]2-, [Zn(CH3S)]+, [Zn(CH3S)2], [Zn(CH3S)3]-, [Zn(CH3S)4]2-, [Zn(CH3SH)]2+, [Zn(CH3SCH3)]2+, [Zn(C6H5S)]+, [Zn(C6H5S)2], [Zn(C6H5S)3]-, [Zn(HS)(NH=CH2)2]+, [Zn(HS)2(NH=CH2)2], [Zn(HS)(H2O)]+, [Zn(HS)(HCOO)], [Zn(HS)2(HCOO)]-, [Zn(CH3O)]+, [Zn(CH3O)2], [Zn(CH3O)3]-, [Zn(CH3O)4]2, [Zn(CH3OH)]2+, [Zn(HCOO)]+, [Zn(CH3COO)]+, [Zn(CH3COO)2], [Zn(CH3COO)3]-, [Zn(CO3)], [Zn(HCO3)]+, and [Zn(HCO3)(Imz)]+ (Imz, 1,3-imidazole). The computed Zn-S bond distances are 2.174A for [ZnS], 2.274 for [Zn(HS)]+, 2.283 for [Zn(CH3S)]+, and 2.271 for [Zn(C6H5S)]+, showing that sulfide anion forms stronger bonds than substituted sulfides. The nature of the substituents on sulfur influences only slightly the Zn-S distance. The optimized tetra-coordinate [Zn(HS)2(NH=CH2)2] molecules has computed Zn-S and Zn-N bond distances of 2.392 and 2.154A which compare well with the experimental values at the solid state obtained via X-ray diffraction for a number of complex molecules. The computed Zn-O bond distances for chelating carboxylate derivatives like [Zn(HOCOO)]+ (1.998A), [Zn(HCOO)]+ (2.021), and [Zn(CH3COO)]+ (2.001) shows that the strength of the bond is not much influenced by the substituent on carboxylic carbon atom and that CH3- and HO- groups have very similar effects. The DFT analysis shows also that the carboxylate Ligand has a preference for the bidentate mode instead of the monodentate one, at least when the coordination number is small.

Color duplex scanning for the identification of extracranial atherosclerosis in patients with suspected coronary artery disease.

BACKGROUND: The presence of extracranial artery disease has been used as a predictor of coronary artery disease (CAD). The present study was conducted to test the prevalence of extracranial artery disease among patients with suspected CAD. METHODS: Among candidates for coronary arteriography, 400 consecutive patients (mean age 63 +/- 11 years, 78% males, 22% females) underwent color duplex ultrasound of carotid arteries. RESULTS: Extracranial artery disease was documented in 60 patients (15%), CAD in 309 patients (77%). Patients with extracranial artery disease were significantly older (p < 0.001), smoked a higher amount of pack-years (p < 0.001), showed a higher incidence of diabetes (p < 0.01), hypertension (p < 0.05) and CAD (p < 0.05) when compared to extracranial artery disease-free subjects. Plotting age against extracranial artery disease and CAD distribution, extracranial artery disease occurred later in life than CAD (p < 0.001). The best cut-off point of age for predicting extracranial artery disease was 68 years. Carotid angiography was performed in 114 patients after cardiac catheterization (k = 0.8044 with color duplex scanning). CONCLUSIONS: Extracranial artery disease is frequent among patients undergoing coronary arteriography. Carotid ultrasound screening is useful in older patients.

Oxygen Radical Scavenger Activity, EPR, NMR, Molecular Mechanics and Extended-Hückel Molecular Orbital Investigation of the Bis(Piroxicam)Copper(II) Complex.

The oxygen radical scavenger activity (ORSA) of [Cu(II)(Pir)(2)] (HPir = Piroxicam = 4-hydroxy -2- methyl -N-2- pyridyl -2H- 1,2-benzothiazine -3- carboxamide 1,1-dioxide) was determined by chemiluminescence of samples obtained by mixing human neutrophils (from healthy subjects) and [Cu(II)(Pir)(2)(DMF)(2)] (DMF = N,N -dimethylformammide) in DMSO/GLY/PBS (2:1:2, v/v) solution (DMSO = dimethylsulfoxide, GLY = 1,2,3-propantriol, PBS = Dulbecco's buffer salt solution). The ratio of the residual radicals, for the HPir (1.02.10(-4)M) and [Cu(II)(Pir)(2)(DMF)(2)] (1.08.10(-5)M)/HPir (8.01.10-(-5)M) systems was higher than 12 (not stimulated) [excess of piroxicam was added (Cu/Pir molar ratio approximately 1:10) in order to have most of the metal complexed as bischelate]. In contrast, the ratio of residual radicals for the CuCl(2) (1.00.10(-5)M) and [Cu(II)(Pir)(2)(DMF)(2)] (1.08.10(-5)M)/Hpir (8.01.10(-5)M)system was 5. The [Cu(II)(Pir)(2)] compound is therefore a stronger radical scavenger than either HPir or CuCl(2). A molecular mechanics (MM) analysis of the gas phase structures of neutral HPir, its zwitterionic (HPir(+-)) and anionic (Pir(-)) forms, and some Cu(II)-piroxicam complexes based on X-ray structures allowed calculation of force constants. The most stable structure for HPir has a ZZZ conformation similar to that found in the Cu(II) (and Cd(II) complexes) in the solid state as well as in the gas phase. The structure is stabilized by a strong H bond which involves the N(amide)-H and O(enolic) groups. The MM simulation for the [Cu(II)(Pir)(2)(DMF)(2)] complex showed that two high repulsive intramolecular contacts exist between a pyridyl hydrogen atom of one Pir(-) molecule with the O donor of the other ligand. These interactions activate a transition toward a pseudo-tetrahedral geometry, in the case the apical ligands are removed. On refluxing a suspension of [Cu(II)(Pir)(2)(DMF)(2)] in acetone a brown microcystalline solid with the Cu(Pir)(2).0.5DMF stoichiometry was in fact prepared. (13)C spin-lattice relaxation rates of neutral, zwitterionic and anionic piroxicam, in DMSO solution are explained by the thermal equilibrium between the three most stable structures of the three forms, thus confirming the high quality of the force field. The EPR spectrum of [Cu(II)(Pir)(2)(DMF)(2)] (DMSO/GLY, 2:1, v/v, 298 and 110 K) agrees with a N2O2+O2 pseudo-octahedral coordination geometry. The EPR spectrum of [Cu(II)(Pir)(2).0.5DMF agrees with a pseudo-tetrahedral coordination geometry. The parameters extracted from the room temperature spectra of the solution phases are in agreement with the data reported for powder and frozen solutions. The extended-Hückel calculations on minimum energy structures of [Cu(II)(Pir)(2)(DMF)(2)] and [Cu(II)(Pir)(2)] (square planar) revealed that the HOMOs have a relevant character of d(x) (2)-y(2). On the other hand the HOMO of a computer generated structure for [Cu(II)(Pir)(2)] (pseudo-tetrahedral) has a relevant character of d(xy) atomic orbital. A d(xy) orbital is better suited to allow a dpi-ppi interaction to the O(2) (-) anion. Therefore this work shows that the anti-inflammatory activity of piroxicam could be due in part to the formation of [Cu(II)(Pir)(2)] chelates, which can exert a SOD-like activity.

Relation of prognosis in sick sinus syndrome to age, conduction defects and modes of permanent cardiac pacing.

A large population of sick sinus syndrome (SSS) patients was analyzed to determine whether age of patients, presence of conduction disturbances and mode of permanent pacing are related to the occurrence of supraventricular tachyarrhythmias, cerebral embolism and cardiac mortality. Three hundred thirty-nine patients permanently paced (135 AAI, 79 DDD, 125 VVI) because of SSS were followed for a mean period of 5 years (range 2 to 10). Patients were divided into 4 groups according to age (less than 70 or greater than 70 years) and the presence or absence of an associated conduction disturbance. Sixty-eight percent of VVI, 55% of AAI and 40.5% of DDD patients were greater than 70 years of age. In the VVI and DDD groups a conduction disturbance was present in 67 of 204 (33%) patients; conduction disturbances were more common in patients greater than 70 years old (46 of 111, 41%) than in those less than 70 years old (21 of 93,22%). The Wenckebach threshold (greater than 140 beats/min) remained unchanged during the follow-up period in 82% of AAI patients. In 9% of these patients, the Wenckebach threshold showed some degree of deterioration, but only in 2 patients was it less than 100 beats/min (1.5%). Spontaneous second-degree atrioventricular block was observed in 7 patients (5%); it disappeared in 6 of these patients when drug therapy was discontinued.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of purine nucleotides with inert paramagnetic Cr(III) probes evaluated by NMR relaxation effects. Molecular mechanics calculations on Cr(III) and Co(III) polyphosphate complexes.

The 1H NMR relaxation effects produced by paramagnetic Cr(III) complexes on nucleoside 5'-mono- and -triphosphates in D2O solution at pH' = 3 were measured. The paramagnetic probes were [Cr(III)(H2O)6]3+, [Cr(III)(H2O)3(HATP)], [Cr(III)(H2O)3(HCTP)] and [Cr(III)(H2O)3(UTP)-, while the matrix nucleotides (0.1 M) were H2AMP, HIMP-, and H2ATP2-. For the aromatic base protons, the ratios of the transverse to longitudinal paramagnetic relaxation rates (R2p/R1p) for the [Cr(III)(H2O)6]3+/H2ATP2-, [Cr(III)(H2O)3(HATP)]/H2ATP2-, [Cr(III)(H2O)3(HCTP)]/H2ATP2 and [Cr(III)(H2O)3(UTP)]-/H2ATP2 systems were below 2.33 so the dipolar term predominates. For a given nucleotide, R1p for the purine H(8) signal was larger than for the H(2) signal with the [Cr(III)(H2O)6]3+ probe, while R1p for the H(2) signal was larger with all the other Cr(III) probes. Molecular mechanics computations on the [Cr(III)(H2O)4(HPP)(alpha,beta)], [Cr(III)(NH3)4(HPP)(alpha,beta)], [Co(III)(NH3)3(H2PPP)(alpha,beta,gamma)] and [Co(III)(NH3)4(HPP)(alpha,beta)] complexes gave calculated energy-minimized geometries in good agreement with those reported in crystal structures. The molecular mechanics force constants found were then used to calculate the geometry of the inner sphere [Cr(III)(H2O)6]3+ and [Cr(III)(H2O)3(HATP)(alpha,beta,gamma)] complexes as well as the structures of the outer sphere [Cr(III)(H2O)6]3(+)-(H2AMP) and [Cr(III)(H2O)6]-(HIMP)- species. The gas-phase structure of the [Cr(III)(H2O)3(HATP)(alpha,beta,gamma)] complex shows the existence of a hydrogen bond interaction between a water ligand and the adenine N(7)(O...N = 2.82 A). The structure is also stabilized by intramolecular hydrogen bonds involving the -O(2')H group and the adenine N(3) (O...N = 2.80 A) as well as phosphate oxygen atoms and a water molecule (O...O = 2.47 A). The metal center has an almost regular octahedral coordination geometry. The structures of the two outer-sphere species reveal that the phosphate group interacts strongly with the hexa-aquochromium probe. In both complexes, the nucleotides have a similar "anti" conformation around the N(9)-C(1') glycosidic bond. However, a very important difference characterizes the two structures. For the (HIMP)- complex, strong hydrogen bond interactions exist between one and two water ligands and the inosine N(7) and O(6) atoms, respectively (O...O = 2.63 A; O...N = 2.72, 2.70 A). For the H2AMP complex, the [Cr(III)(H2O)6]3+ cation does not interact with N(7) since it is far from the purine system. Hydrogen bonds occur between water ligands and phosphate oxygens. The Cr-H(8) and Cr-H(2) distances revealed by the energy-minimized geometries for the two outer sphere species were used to calculate the R1p values for the H(8) and H(2) signals for comparison with the observed R1p values: 0.92(c), 1.04(ob) (H(8)) and 0.06(c), 0.35(ob) (H(2)) for H2AMP; and 3.76(c), 4.53(ob) (H(8)) and 0.16(c), 0.77(ob) s-1 (H(2)) for HIMP-.(ABSTRACT TRUNCATED AT 400 WORDS)

Crystal structure of the alpha, beta, gamma-tridentate manganese complex of adenosine 5'-triphosphate cocrystallized with 2,2'-dipyridylamine.

The 1:1:1 complex of Mn2+, ATP, and 2,2'-dipyridylamine (DPA) crystallizes as Mn-(HATP)2.Mn(H2O)6.(HDPA)2.12H2O in the orthorhombic space group C222(1) with unit cell dimensions a = 10.234 (3) A, b = 22.699 (3) A, and c = 31.351 (4) A. The structure was solved by the multisolution technique and refined by the least-squares method to a final R index of 0.072 using 3516 intensities. The structure is composed of two ATP molecules sharing a common manganese atom. The metal exhibits alpha, beta, gamma coordination to the triphosphate chains of two dyad-related ATP molecules, resulting in a hexacoordinated Mn2+ ion surrounded by six phosphate groups. The metal to oxygen distances are 2.205 (6), 2.156 (4), and 2.144 (5) A for the alpha-, beta-, and gamma-phosphate groups, respectively. No metal-base interactions are observed. There is a second hexaaqua-coordinated Mn2+ ion that is also located on a dyad axis. The hydrated manganese ions sandwich the phosphate-coordinated manganese ions in the crystal with a metal-metal distance of 5.322 A. The ATP molecule is protonated on the N(1) site of the adenine base and exhibits the anti conformation (chi = 66.0 degrees). The ribofuranose ring is in the 2/3 T conformation with pseudorotation parameters P = 179 (1) degrees and tau m = 34.1 (6) degrees. The adenine bases form hydrogen-bonded self-pairs across a crystallographic dyad axis and stack with both DPA molecules to form a column along the dyad. The structure of the metal-ATP complex provides information about the possible metal coordination, conformation, and environment of the nucleoside triphosphate substrate in the enzyme.

Interaction of adenosine 5'-triphosphate with metal ions X-ray structure of ternary complexes containing Mg(II), Ca(II), Mn(II), Co(II), ATP and 2,2'-dipyridylamine.

The X-ray structures of the isomorphous Mg2+, Ca2+, Mn2+ and Co2+ complexes of ATP have been determined. The metal ions are wrapped in hexa-coordination by the alpha, beta and gamma phosphate groups of two ATP molecules thus blocking the interaction of the metal ions with the adenine base. A second metal ion which is fully hydrated, M(H2O)2+(6), is engaged in a strong hydrogen bond with the gamma phosphate group of ATP and suggests a possible step in facilitating the cleavage between the beta and gamma phosphates in phosphoryl transfer reactions.

Ternary complexes between adenosine 5' -triphosphoric acid, 2,2'-bipyridyl and the divalent metal ions manganese (II), cobalt (II), copper (II), and zinc (II). Preparation and physiochemical properties.

A series of ternary complexes between adenosine 5'-triphosphoric acid (ATP), 2,2'-bipyridyl, and the transition metal ions manganese (II), cobalt(II), copper (II), and zinc(II) in the ratio 1:1:1 have been prepared. The solid compounds are crystalline and can be formulated as [M(II)-H2ATP-2,2'-Bipyridyl]2 . 4H2O (MATPbipy). X-ray powder patterns show them to be all isomorphous. Potentiometric titrations in aqueous solutions are in agreement with the presence of two ionizable protons. Ultraviolet and visible spectra, epr, and magnetic susceptibility measurements suggest that the metal ions have a high-spin distorted octahedral coordination. From infrared spectra it can be deduced that ATP coordinates to the metal only through the oxygen atoms of the phosphate groups. These compounds, which are particularly stable towards hydrolysis, form possible models for ATP transport in biological fluids.