Biological phosphonates: determination by phosphorus-31 nuclear magnetic resonance

Advanced methods of phosphorus-31 nuclear magnetic resonance spectroscopy provided a method whereby biological phosphonates and phosphates can be determined on simple lipid fractions of biological origin. The spectra consist of two easily distinguished resonance bands; one corresponds to families of phosphonates, and the other corresponds to families of orthophosphates.     

Noninvasive study of high-energy phosphate metabolism in human heart by depth-resolved 31P NMR spectroscopy

Phosphorus-31 nuclear magnetic resonance (NMR) spectra showing the relative concentrations of high-energy phosphate metabolites have been recorded noninvasively from the human heart in vivo. Spectral data were spatially localized by combining a pulsed magnetic field gradient with surface NMR excitation-detection coils. The location of the selected spectral region was determined by conventional proton NMR imaging immediately before examination by phosphorus-31 NMR spectroscopy.     

Nuclear magnetic resonance technology for medical studies

Nuclear magnetic resonance proton imaging provides anatomical definition of normal and abnormal tissues with a contrast and detection sensitivity superior to those of x-ray computed tomography in the human head and pelvis and parts of the cardiovascular and musculoskeletal systems. Recent improvements in technology should lead to advances in diagnostic imaging of the breast and regions of the abdomen. Selected-region nuclear magnetic resonance spectroscopy of protons, carbon-13, and phosphorus-31 has developed into a basic science tool for in vivo studies on man and a unique tool for clinical diagnoses of metabolic disorders. At present, nuclear magnetic resonance is considered safe if access to the magnet environment is controlled. Technological advances employing field strengths over 2 teslas will require biophysical studies of heating and static field effects.     

Phosphorus-proton spin-spin coupling and conformation of a dinucleoside phosphate

The phosphorus-31 nuclear magnetic resonance spectrum of beta-adenosine-3'-beta-adenosine-5'-phosphoric acid in its aqueous solution (pH = 9.2) was studied. The signal consisted of eight peaks caused by the spin-spin coupling of the phosphorus nucleus with three protons, two on the 5' carbon, and one on the 3' carbon. The coupling constants were 3.4, 6.5, and 8.1 hertz; from these values the dihedral angles of the three P-O-C-H systems were estimated.     

Monitoring the time course of cerebral deoxyglucose metabolism by 31P nuclear magnetic resonance spectroscopy

The phosphorylation of 2-deoxyglucose by the mammalian brain is used as an index of the brain's energy metabolism. The results of phosphorus-31 nuclear magnetic resonance (31P NMR) monitoring of conscious animals in vivo showed rapid phosphorylation of 2-deoxyglucose by brain tissue. The rate of phosphorylation as determined by 31P NMR was consistent with results achieved by tracer methods using carbon-14-labeled 2-deoxyglucose. However, the disappearance of 2-deoxyglucose-6-phosphate was shown to be faster than that reported by tracer studies and occurred without alterations of intracellular pH and energy homeostasis. These results were confirmed by gas chromatography and mass spectroscopy. It is postulated that 2-deoxyglucose may be metabolized in several ways, including dephosphorylation by a hexose phosphatase.     

Intracellular pH Regulates Transitions Between Dormancy and Development of Brine Shrimp (Artemia salina) Embryos

The intracellular pH (pH(i))of encysted gastrula-stage embryos of the brine shrip, Artemia, as previously shown by in vivo phosphorus-31 nuclear magnetic resonance spectroscopy, increases by more than 1 unit during arousal from cryptobiotic dormancy and decreases by the same amount during reinduction of dormancy. These changes in pH(i) are now shown to be a fundamental regulator of the transitions between dormancy and metabolism: acidification of activated embryo pH(i) by more than 1 unit with carbon dioxide induced a state comparable to natural dormancy, while alkalinization of dormant embryo pH(i) with the weak base ammonia terminated natural dormancy. This demonstration of pH(i)-mediated regulation of cryptobiotic dormancy extends the known scope for pH(i) as a regulator of development to include multicellular stages of the metazoan life cycle.     

In vivo one-dimensional imaging of phosphorus metabolites by phosphorus-31 nuclear magnetic resonance

A phosphorus-31 nuclear magnetic resonance imaging technique has been used to obtain information on phosphorus metabolites from different spatial regions of tissues in vivo. The technique for selection of planes through the tissue is based on phase-encoding of spin echoes and was used to obtain one-dimensional discrimination of phosphorus-31 spectra from different parts of the tissue simultaneously. Specimens were resolved into 16 distinct slices and a signal-to-noise ratio of about 20 to 1 was obtained in 1/2 hour. Results are presented for phantoms, rat legs, and gerbil heads.     

兴安落叶松木材提取物的组成分析

采用＾１３ＣＮＭＲ核磁共振波谱法、光吸收法和化学分析方法对兴安落叶松的心、边材抽出物进行了定量分析，测定了不同溶剂抽出物的含量及有关组成，实验数据可为落叶松的加工利用及化学改性提供理论依据。     

Sweat in schizophrenic patients: identification of the odorous substance

The substance causing the peculiar odor in sweat of schizophrenic patients has been isolated and identified as trans-3-methyl-2-hexenoic acid by gas chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy. The natural and the synthetic compounds were cleaves across the double bond to give 2-pentanone and oxalic acid, thereby confirming the structure.     

TAUTOMERISM AND PROTONATION OF GUANOSINE

Guanosine has been demonstrated, by infrared and nuclear magnetic resonance spectroscopy, to have a keto-amino structure in neutral aqueous solution and to undergo protonation at N(7) in acid solution.     

γ-聚谷氨酸高吸水树脂的结构和形态

摘要采用红外光谱（IR）、核磁共振（NMR）、原子力显微镜（AFM）对γ-聚谷氨酸高吸水树脂进行了结构分析和形态袁征,结果发现,在聚乙二醇缩水甘油醚交联剂的存在下,γ-聚谷氨酸能够充分交联,树脂具有良好的吸水性能。     

DNA conformation, dynamics, and interactions in solution

The conformation and dynamics of the d(CGCGAATTCGCG) duplex, its analogs containing mismatched base pairs and helix interruptions, and its complexes with actinomycin and Netropsin, bound separately and simultaneously, have been investigated by nuclear magnetic resonance spectroscopy in aqueous solution. Structural information has been deduced from chemical shift and nuclear Overhauser effect parameters, while the kinetics have been probed from line width and saturation recovery experiments on proton and phosphorus markers at the individual base pair level. These studies lead to an improved understanding of the role of nucleic acid sequence on the structure, flexibility, and conformational interconversions in the duplex state. The nuclear magnetic resonance measurements readily identify helix modification and antibiotic binding sites on the nucleic acid and estimate the extent to which the observed conformational and dynamic perturbations are transmitted to adjacent base pair regions.     

Nuclear magnetic resonance measurement of oil "unsaturation" in single viable corn kernels

High-resolution nuclear magnetic resonance spectroscopy has been used to demonstrate the feasibility of determining iodine value and average molecular weight of oil in individual corn kernels. The procedure is rapid and nondestructive. Depending on heritability of individual fatty acids, this technique may greatly increase selection efficiency in breeding programs to alter the fatty acid composition of corn oil.     

In vivo determination of the pyridine nucleotide reduction charge by carbon-13 nuclear magnetic resonance spectroscopy

An intracellular coenzyme has been observed by carbon-13 nuclear magnetic resonance spectroscopy. The pyridine nucleotides in Escherichia coli were specifically labeled with carbon-13 from the biosynthetic precursor, nicotinic acid. The intracellular redox status and metabolic transformations of the pyridine nucleotides were examined under a variety of conditions. A highly reduced nicotinamide adenine dinucleotide pool was observed under anaerobic conditions only in cells that were cultured aerobically on glycerol.     

Cadmium-113 magnetic resonance spectroscopy

Cadmium-113 nuclear magnetic resonance spectroscopy has been used in studies of the structure and dynamics of inorganic and bioinorganic molecules. Chemical dynamics play an important role in the analysis of relaxation and chemical shift data. Na?ve interpretations of relaxation data can be checked by performing these experiments at a variety of temperatures and magnetic field strengths. A combination of solid- and liquid-state nuclear magnetic resonance measurements can provide the user with unambiguous data on chemical shielding. These data can be used to characterize zinc and calcium ion binding sites in metalloproteins.     

水田土壤富里酸组分的结构表征及对多环芳烃芘的吸附特征

本文依次用pH4.8、pH7.0及pH11.0的通用缓冲液、水和乙醇,梯度淋洗吸附富里酸的XAD-8树脂,根据其不同解离程度及亲水性质将富里酸细分为5个组分(包括3个亲水性组分和2个疏水性组分);利用元素分析、红外光谱和核磁共振等分析方法确定各组分的理化特征,并研究各组分对特定多环芳烃(芘)的吸附特性.结果表明,按照淋洗次序,后分离的组分其羧基碳含量低于先分离的组分,烷基碳含量则高于后者;芘在被水和乙醇淋洗出的两种组分上的吸附等温线体现出良好的线性;组分中的烷基组分对吸附有促进作用,相反,羧基和羰基不利于芘的吸附,表明梯度淋洗分组方法对研究芘与富里酸的作用机理是十分有效的.     

Nuclear magnetic resonance at high pressure

Nuclear magnetic resonance relaxation measurements at high pressure provide unique information about the microscopic behavior of liquids. This article presents the principles of this technique; illustrates its usefulness by several specific examples of studies of molecular liquids, water, and supercritical dense fluids; and indicates the promising future of high-resolution nuclear magnetic resonance spectroscopy at high pressure with examples of studies of chemical exchange and homogeneous catalytic processes.     

Intercalation complex of proflavine with DNA: structure and dynamics by solid-state NMR

The structure of the complex formed between the intercalating agent proflavine and fibrous native DNA was studied by one- and two-dimensional high-resolution solid-state nuclear magnetic resonance (NMR). Carbon-13-labeled proflavine was used to show that the drug is stacked with the aromatic ring plane perpendicular to the fiber axis and that it is essentially immobile. Natural abundance carbon-13 NMR of the DNA itself shows that proflavine binding does not change the puckering of the deoxyribose ring. However, phosphorus-31 NMR spectra show profound changes in the orientation of the phosphodiester grouping on proflavine binding, with some of the phosphodiesters tilting almost parallel to the helix axis, and a second set almost perpendicular. The first group to the phosphodiesters probably spans the intercalation sites, whereas the tilting of the second set likely compensates for the unwinding of the DNA by the intercalator.     

Unitary control in quantum ensembles: maximizing signal intensity in coherent spectroscopy

Experiments in coherent magnetic resonance, microwave, and optical spectroscopy control quantum-mechanical ensembles by guiding them from initial states toward target states by unitary transformation. Often, the coherences detected as signals are represented by a non-Hermitian operator. Hence, spectroscopic experiments, such as those used in nuclear magnetic resonance, correspond to unitary transformations between operators that in general are not Hermitian. A gradient-based systematic procedure for optimizing these transformations is described that finds the largest projection of a transformed initial operator onto the target operator and, thus, the maximum spectroscopic signal. This method can also be used in applied mathematics and control theory.