Phosphoryl Bond Research Articles

On the Nature of the Carbonyl versus Phosphoryl Binding in Uranyl Nitrate Complexes†.

The electronic structure of ligands with phosphoryl and carbonyl binding sites and their complexation behavior with uranyl nitrate were investigated using density functional theory (DFT). The quantum chemical calculations indicate that the electronic charges on both phosphoryl and carbonyl groups are more polarized toward oxygen atoms in isolated ligands. This effect is predominant in the case of complexes of the former. Both P═O and C═O groups are positively charged with the exception in methylisobutylketone (MIBK), where the C=O group is virtually neutral. The fragment molecular orbital analysis suggests that during complexation, a certain amount of charge transfer occurs from the filled pπ-orbitals [πx(CO/PO) and πy(CO/PO)] of the ligand to 5f, 6d, and 7s orbitals of the uranium atom (fσ* and dsσ*). The NBO analysis reaffirms the charge transfer mechanism. The observed red shift in ν(C═O) and ν(P═O) identified in the simulated infrared spectrum of the corresponding complexes implies a moderate weakening of both carbonyl and phosphoryl bonds upon complexation. The atoms in molecules (AIM) analysis suggests a stronger phosphoryl binding compared to carbonyl interactions and an ionic U-O bond. The estimated complexation energies are considerable for phosphoryl ligands compared to those of the carbonyl analogue, with a reasonably large value derived for tri-n-butyl phosphate (TBP). The energy decomposition analysis marked significant stabilizing orbital interactions for phosphoryl ligands. The contributions of estimated dispersion energies are considerable in all complexes and extensively depend on the alkyl unit.

Direct Electrochemical P(V) to P(III) Reduction of Phosphine Oxide Facilitated by Triaryl Borates.

Triaryl borate Lewis acids facilitate the direct two-electron reduction of the P(V) center of triphenylphosphine oxide (TPPO) to the P(III) center of triphenylphosphine at faradaic efficiencies of 37%. Insight from direct P(V) to P(III) reduction is provided from cyclic voltammetry. The electrochemical reduction of TPPO proceeds through an unusual ECrECi mechanism in which the breaking of the phosphoryl bond in a two-electron-reduced association complex with the triaryl borate is rate-determining. The rate and faradaic efficiency for TPPO reduction are tuned by judicious choice of substituents on triaryl borate, with tris(4-methoxyphenyl) borate demonstrating the highest for both. These results suggest that an attractive route toward the room-temperature reduction of phosphate for phosphorus reclamation is greatly facilitated by the stabilization of reduced phosphate intermediates through their association with Lewis acids.

A density functional theory study on the interaction between UO22+ and the carbamoylphosphoramidic acid ligand for uranium extraction from seawater

Phosphorylurea molecules, which contain both phosphoryl and carbonyl groups, are considered efficient extractants for UO22+. This study aims to explain the complexation of UO22+ with carbamoylphosphoramidic acid (CPO), a simple model for phosphorylurea, for ligand design for uranium recovery from seawater using density functional theory calculations, natural bond order analysis, and the quantum theory of atoms in molecules. The results showed that, when CPO acts as a monodentate ligand, the affinity of phosphoryl for UO22+ is stronger than that of carbonyl, and CPO coordinates with UO22+ through the phosphoryl oxygen atom. When CPO serves as a bidentate ligand, both the phosphoryl and carbonyl oxygen atoms connect to UO22+, and the U–O(carbonyl) bond plays a more important role than the U–O(phosphoryl) bond in the interaction between UO22+ and CPO. This paradox may be caused by the significant charge transfer from the U–O(carbonyl) π bond orbital to the C–N σ antibond orbital of the bidentate CPO. The NH spacer between the phosphoryl and carbonyl groups could ensure the delocalization of the electron system of the molecule. The bidentate binding motif is favored by entropy and opposed by enthalpy, while the monodentate binding motif is favored by enthalpy and opposed by entropy. Ultimately, the bidentate binding motif is more favorable than the monodentate one. As expected, the interaction between UO22+ and the deprotonated CPO is stronger than that between UO22+ and the neutral CPO. Comparing the interaction between UO22+ and CPO with that between UO22+ and N-phenylcarbamoylphosphoramidic acid (PhCPO), formed by replacing one hydrogen atom from the terminal nitrogen atom of CPO with a phenyl group, the phenyl substituent at the terminal nitrogen atom of PhCPO shows a slightly negative effect on the interaction between UO22+ and PhCPO.

Chemoselective reduction of the phosphoryl bond of O-alkyl phosphinates and related compounds: an apparently impossible transformation.

A method is reported for the phosphoryl bond cleavage of O-alkyl phosphinates, phosphinothioates and certain phosphonamidates to furnish the corresponding P(III) borane adducts. The two-step procedure relies upon initial activation of the phosphoryl bond with an alkyl triflate, followed by reduction of the resulting intermediate using lithium borohydride.

Characterization of Recombinant ELMOD (Cell Engulfment and Motility Domain) Proteins as GTPase-activating Proteins (GAPs) for ARF Family GTPases

The ARF family of regulatory GTPases, within the RAS superfamily, is composed of ~30 members in mammals, including up to six ARF and at least 18 ARF-like (ARL) proteins. They exhibit significant structural and biochemical conservation and regulate a variety of essential cellular processes, including membrane traffic, cell division, and energy metabolism; each with links to human diseases. We previously identified members of the ELMOD family as GTPase-activating proteins (GAPs) for ARL2 that displayed crossover activity for ARFs as well. To further characterize the GAP activities of the three human ELMODs as GAPs we developed new preparations of each after overexpression in human embryonic kidney (HEK293T) cells. This allowed much higher specific activities and enhanced stability and solubility of the purified proteins. The specificities of ELMOD1-3 as GAPs for six different members of the ARF family were determined and found to display wide variations, which we believe will reveal differences in cellular functions of family members. The non-opioid sigma-1 receptor (S1R) was identified as a novel effector of GAP activity of ELMOD1-3 proteins as its direct binding to either ELMOD1 or ELMOD2 resulted in loss of GAP activity. These findings are critical to understand the roles of ELMOD proteins in cell signaling in general and in the inner ear specifically, and open the door to exploration of the regulation of their GAP activities via agonists or antagonists of the S1R.

Reaction Dynamics of ATP Hydrolysis in Actin Determined by ab Initio Molecular Dynamics Simulations.

Energy released by the hydrolysis of the high-energy phosphate bond of nucleoside triphosphate (NTP) cofactors is the driving force behind most biological processes. To understand how this energy is used to induce differences in protein structure and function, we examine the transfer of vibrational energy into the nucleotide-bound actin active site immediately after reaction activation. To this end, we perform Born-Oppenheimer molecular dynamics simulations of the active site at the level of density functional theory (DFT) starting at the calculated transition state (TS) structure. Similarly to the mechanism determined in many nucleotide-bound protein systems, the Os-Pγ bond is first elongated. Then, nucleophilic attack of the lytic water on Pγ occurs. Subsequently, protons are transferred in a cycle formed by water molecules, a protein residue, Asp154, and the γ-phosphate group, resulting in the formation of H2PO4(-). To investigate the possible creation of excited vibrational states in the products, power spectra of bond-length autocorrelation functions for relevant bonds within the active site are compared for simulations that start at the TS, at reactants, and at reaction end products. The hydroxyl bond formed in the final proton transfer to the phosphate molecule is observed to exhibit relatively high kinetic energies and large oscillations during reaction. It is also likely that some of the energy released by the reaction is captured by the low-energy stretching vibrations of the phosphoryl bonds of orthophosphate, which oscillate with large amplitudes in nonequilibrium simulations of end products.

Characterization of CMPO and its radiolysis products by direct infusion ESI-MS

Direct infusion electrospray ionization mass spectrometry (ESI-MS) approaches were developed for rapid identification of impurity compounds formed from octylphenyl-(N,N-(diisobutyl)carbamoylmethyl) phosphine oxide (CMPO) during alpha and gamma irradiation experiments of this compound in dodecane. CMPO is an aggressive Lewis base, and produces extremely abundant metal complex ions in the ESI-MS analysis that make identification of low abundance compounds that are less nucleophilic challenging. Radiolysis products were identified using several approaches including restricting ion trapping so as to exclude the abundant natiated CMPO ions, extraction of acidic products using aqueous NaOH, and extraction of basic products using HNO3. These approaches generated protonated, natiated and deprotonated species derived from CMPO degradation products formed via radiolytic cleavages of several different bonds. Cleavages of the amide and methylene–phosphoryl bonds appear to be favored by both alpha and gamma irradiation, while alpha irradiation also appears to induce cleavage of the methylene–carbonyl bond. The degradation products observed are formed from recombination of the initially formed radicals with hydrogen, methyl, isopropyl and hydroxyl radicals that are derived either from CMPO, contacted aqueous nitric acid, or the dodecane solvent.

Insight into the phosphodiesterase mechanism from combined QM/MM free energy simulations.

Molecular dynamics simulations employing a combined quantum mechanical and molecular mechanical potential have been carried out to elucidate the reaction mechanism of the hydrolysis of a cyclic nucleotide cAMP substrate by phosphodiesterase 4B (PDE4B). PDE4B is a member of the PDE superfamily of enzymes that play crucial roles in cellular signal transduction. We have determined a two-dimensional potential of mean force (PMF) for the coupled phosphoryl bond cleavage and proton transfer through a general acid catalysis mechanism in PDE4B. The results indicate that the ring-opening process takes place through an S(N)2 reaction mechanism, followed by a proton transfer to stabilize the leaving group. The computed free energy of activation for the PDE4B-catalyzed cAMP hydrolysis is about 13 kcal·mol(-1) and an overall reaction free energy is about -17 kcal·mol(-1), both in accord with experimental results. In comparison with the uncatalyzed reaction in water, the enzyme PDE4B provides a strong stabilization of the transition state, lowering the free energy barrier by 14 kcal·mol(-1). We found that the proton transfer from the general acid residue His234 to the O3' oxyanion of the ribosyl leaving group lags behind the nucleophilic attack, resulting in a shallow minimum on the free energy surface. A key contributing factor to transition state stabilization is the elongation of the distance between the divalent metal ions Zn(2+) and Mg(2+) in the active site as the reaction proceeds from the Michaelis complex to the transition state.

Cyclodiphosph(III)azane chemistry – Ylides from the reaction of [(RNH)P-N( t-Bu)] 2 [R = t-Bu, i-Pr] with dimethyl maleate and chiral ansa-type derivatives from reaction of [ClP-N( t-Bu)] 2 with a substituted BINOL

Use of a simple inorganic ring system with the cyclodiphosph(III)azane skeleton [e.g. [(RNH)P-N( t-Bu)] 2 [R = t-Bu ( 7), i-Pr ( 8)] to probe some of the intermediates proposed in phosphine mediated organic reactions is highlighted. Thus the reaction of 7– 8 with the allenylphosphine oxide Ph 2P(O)C(Ph) C CH 2 ( 9) affords the phosphinimines [(RNH)P(μ-N- t-Bu) 2 P( N-R)-C( CH 2)CH(Ph)-P(O)Ph 2] [R = t-Bu ( 10), i-Pr ( 11)], while a similar reaction of 7– 8 with dimethyl maleate (or dimethyl fumarate) affords the ylides [(RNH)P(μ-N- t-Bu) 2 P(NH-R) C(CO 2Me)-CH 2(CO 2Me) [R = t-Bu ( 18), i-Pr ( 19)]. The implication of such reactions on phosphine mediated organic transformations including Morita–Baylis–Hillman reaction is mentioned. In a rather rare type of situation, an unusually long phosphoryl (P O) bond [1.538 (5) Å] as revealed the X-ray structure of {( R)-6,6′-( t-Bu) 2-1,1′-(C 10H 5) 2-2,2′-O 2-}{P(O)(N- t-Bu) 2-P(Se)} ( 27) is rationalized by means of crystallographic disorder in packing after comparing the data with that in the literature and {1,1′-(C 10H 6) 2-2,2′-O 2}{P(Se)(N- t-Bu) 2-P(Se)} ( 29). X-ray structures of the new compounds 10– 11, 18– 19, 27 and 29 are discussed. Compound 10 crystallizes in the chiral space group Pca2( 1) with ( S)-chirality at the carbon center [–C( CH 2) CH(Ph)-P] suggesting a case of spontaneous resolution through crystallization.

Anomeric Effect in “High Energy” Phosphate Bonds. Selective Destabilization of the Scissile Bond and Modulation of the Exothermicity of Hydrolysis

A natural bonding orbital (NBO) analysis of phosphate bonding and connection to experimental phosphotransfer potential is presented. Density functional calculations with the 6-311++G(d,p) basis set carried out on 10 model phosphoryl compounds verify that the wide variability of experimental standard free energies of hydrolysis (a phosphotransfer potential benchmark) is correlated with the instability of the scissile O-P bond through computed bond lengths. NBO analysis is used to analyze all delocalization interactions contributing to O-P bond weakening. Phosphoryl bond lengths are found to correlate strongest (R = 0.90) with the magnitude of the ground-state n(O) --> sigma*(O-P) anomeric effect. Electron-withdrawing interactions of the substituent upon the sigma(O-P) bonding orbital also correlate strongly with O-P bond lengths (R = 0.88). However, an analysis of sigma*(O-P) and sigma(O-P) populations show that the increase in sigma*(O-P) density is up to 6.5 times greater than the decrease in sigma(O-P) density. Consequently, the anomeric effect is more important than other delocalization interactions in impacting O-P bond lengths. Factors reducing anomeric power by diminishing either lone pair donor ability (solvent) or antibonding acceptor ability (substituent) are shown to result in shorter O-P bond lengths. The trends shown in this work suggest that the generalized anomeric effect provides a simple explanation for relating the sensitivity of the O-P bond to diverse environmental and substituent factors. The anomeric n(O) --> sigma*(O-P) interaction is also shown to correlate strongly with experimentally determined standard free energies of hydrolysis (R = -0.93). A causal mechanism cannot be inferred from correlation. Equally, a P-value of 1.2 x 10(-4) from an F-test indicates that it is unlikely that the ground-state anomeric effect and standard free energies of hydrolysis are coincidentally related. It is found that as the exothermicity of hydrolysis increases, the energy stabilization of the ground-state anomeric effect increases with selective destabilization of the high-energy O-P bond to be broken in hydrolysis. The anomeric effect therefore partially counteracts a larger resonance stabilization of products that makes hydrolysis exothermic and needs to be considered in achieving improved agreement between calculated and empirical energies of hydrolysis. The avenues relating the thermodynamic behavior of phosphates to underlying structural factors via the anomeric effect are discussed.

Structural Studies of a Stabilized Phosphoenzyme Intermediate of Ca2+-ATPase

Ca(2+)-ATPase belongs to the family of P-type ATPases and maintains low concentrations of intracellular Ca(2+). Its reaction cycle consists of four main intermediates that alternate ion binding in the transmembrane domain with phosphorylation of an aspartate residue in a cytoplasmic domain. Previous work characterized an ultrastable phosphoenzyme produced first by labeling with fluorescein isothiocyanate, then by allowing this labeled enzyme to establish a maximal Ca(2+) gradient, and finally by removing Ca(2+) from the solution. This phosphoenzyme is characterized by very low fluorescence and has specific enzymatic properties suggesting the existence of a high energy phosphoryl bond. To study the structural properties of this phosphoenzyme, we used cryoelectron microscopy of two-dimensional crystals formed in the presence of decavanadate and determined the structure at 8-A resolution. To our surprise we found that at this resolution the low fluorescence phosphoenzyme had a structure similar to that of the native enzyme crystallized under equivalent conditions. We went on to use glutaraldehyde cross-linking and proteolysis for independent structural assessment and concluded that, like the unphosphorylated native enzyme, Ca(2+) and vanadate exert a strong influence over the global structure of this low fluorescence phosphoenzyme. Based on a structural model with fluorescein isothiocyanate bound at the ATP site, we suggest that the stability as well as the low fluorescence of this phosphoenzyme is due to a fluorescein-mediated cross-link between two cytoplasmic domains that prevents hydrolysis of the aspartyl phosphate. Finally, we consider the alternative possibility that phosphate transfer to fluorescein itself could explain the properties of this low fluorescence species.

NMR Studies of the Phosphazene/Phosphazane Rearrangement

AbstractIn compounds such as hydroxy, methoxy and ethoxycyclophosphazenes a phosphazene/ phosphazane rearrangement occurs. In this process the electronic structure of the PN ring system changes under reduction of the endocyclic double bonds. A decrease of the s bond order of the PN bondings results in a decrease of the scalar couplings 1JPN and 2JPP. In addition, considering the solid‐state 31P NMR spectra, significant differences between the phosphazene and phosphazane forms can be observed caused by a change of the local symmetry at the phosphorus atom. In the case of cyclotriphosphazenes a local C2v symmetry exists (strictly valid for these compounds only) and the shielding (shift) tensor is characterized by a small anisotropy as well as a small axiality. Contrary to this in phosphazanes the phosphoryl bond is dominating the chemical shift tensor, characterized by a double to triple anisotropy and a high axiality. Quantum chemical GAUSSIAN calculations reflect these differences between phosphazenes and phosphazanes.

Bonding and 33S NMR chemical shielding in the thiophosphoryl group.

B3LYP and MP2 calculations at the 6-311 + G(nd,p) level (with n = 2 for second-row elements and n = 1 otherwise) were carried out using the atoms-in-molecules (AIM) approach to characterize the thiophosphoryl bond. A series of R(3)PS molecules were studied and compared with the corresponding R(3)PO systems. As with the phosphoryl bond, one cannot distinguish the thiophosphoryl bond from a standard P=S double bond by comparing bond distances. On the basis of the P=S bond in HP=S having a reference bond order of 2.0, the thiophosphoryl bond has a bond order of about 1.6. Examination of localized orbitals show that this bond is less polar than the corresponding PO bond. As with the phosphoryl bond, what sets the thiophosphoryl bond apart is the high degree of back-bonding that contributes to the delocalization index (and covalent bond order) and is the basis for its stronger than single bond character and short bond distance. (33)S NMR shielding calculations were also carried out and, in a few instances, compared directly with newly determined experimental shieldings.

Nature of bonding in the sulfuryl group.

The SO sulfuryl bond in a number of representative sulfoxides and sulfones has been studied at the B3LYP/6-311+G(d,p) level in the atoms-in-molecules (AIM) approach involving the AIM delocalization index and the Cioslowski-Mixon localized orbitals and associated covalent bond order. The sulfur-oxygen covalent bond is strongly polarized toward oxygen and the oxygen lone pairs provide significant backbonding to create short and strong SO bonds, similar in nature to those found in the analogous phosphoryl (PO) bond. Although the sulfoxides in general have larger delocalization indices than the sulfones, there is no correlation between these quantities and the bond dissociation energies.

Atoms-in-Molecules and Electron Localization Function Study of the Phosphoryl Bond

Calculations at the B3LYP/6-311+G(d,p)//B3LYP/6-311+G(d,p) level involving the atoms-in-molecules (AIM) and electron localization function (ELF) methods have been carried out for a variety of PO-bond-containing molecules in an effort to further characterize the phosphoryl bond. One cannot distinguish the phosphoryl bond from a conventional PO double bond by comparing bond distances. Both the bond breaking energies and delocalization indices do divide into the three classes of single, double, and phosphoryl and tend to parallel each other. On the basis of the PO bond in HPO having a reference bond order of 2.0, the phosphoryl bond has a bond order of about 1.3. Examination of localized orbitals confirm our ideas that the phosphoryl bond is highly polar as, indeed, are the other PO bonds. What sets the phosphoryl bond apart is the high degree of back-bonding that contributes to the delocalization index (and covalent bond order) and provides for its stronger-than-single-bond character and short bond distance.

Quantum-Chemical Study of the Structure of Cyanophosphines and Their Oxides

The structure of cyanophosphines and their oxides was studied by ab initio (RHF/6-31G**) and semiempirical (PM3) methods. Both methods predict that MeOP(CN)2, (MeO)2PCN, and (MeO)2P(O)CN exist in noneclipsed antiperiplanar and synclinal conformations. The calculation results nicely agree with measured dipole moments and Kerr constants of these compounds. The phenyl and diphenyl derivatives PhP(CN)2, Ph2PCN, Ph(Et)PCN, and Ph2P(O)CN prefer forms in which the phenyl ring plane is eclipsing the phosphorus lone electron pair or the phosphoryl bond. The interactions of the phosphorus lone electron pair with the phenyl ring and with the cyano group are lacking in the title compounds.

Conformational study of the vinylphosphonic acid and derivatives

AbstractThe alkenyl phosphonics have become interesting compounds for the chemical industry. They have been used as drugs, polymer additives, flame retards, and metal extractants. The electronic structure of the smallest derivatives of this series of compounds, namely, vinylphosphonic acid (VPA), vinylphosphine oxide (VPO), and vinylphosphoryl dichloride (VPDC), are studied here. The nature of the phosphoryl bond was a subject of discussion because its electronic nature could be considered either as a resonance between a double bond and a single polarized bond or as a triple bond with different electronic possibilities. The electronic structure of VPA, VPO, and VPDC have been studied by density functional theory methods using a large basis set. Conformers “s‐cis,” “s‐cis‐gauche,” “s‐trans,” and “s‐trans‐gauche” and rotational barriers are determined for the internal rotational around the CP bond. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2003

Pyrophosphate-producing protein dephosphorylation by HPr kinase/phosphorylase: a relic of early life?

In most Gram-positive bacteria, serine-46-phosphorylated HPr (P-Ser-HPr) controls the expression of numerous catabolic genes ( approximately 10% of their genome) by acting as catabolite corepressor. HPr kinase/phosphorylase (HprK/P), the bifunctional sensor enzyme for catabolite repression, phosphorylates HPr, a phosphocarrier protein of the sugar-transporting phosphoenolpyruvate/glycose phosphotransferase system, in the presence of ATP and fructose-1,6-bisphosphate but dephosphorylates P-Ser-HPr when phosphate prevails over ATP and fructose-1,6-bisphosphate. We demonstrate here that P-Ser-HPr dephosphorylation leads to the formation of HPr and pyrophosphate. HprK/P, which binds phosphate at the same site as the beta phosphate of ATP, probably uses the inorganic phosphate to carry out a nucleophilic attack on the phosphoryl bond in P-Ser-HPr. HprK/P is the first enzyme known to catalyze P-protein dephosphorylation via this phospho-phosphorolysis mechanism. This reaction is reversible, and at elevated pyrophosphate concentrations, HprK/P can use pyrophosphate to phosphorylate HPr. Growth of Bacillus subtilis on glucose increased intracellular pyrophosphate to concentrations ( approximately 6 mM), which in in vitro tests allowed efficient pyrophosphate-dependent HPr phosphorylation. To effectively dephosphorylate P-Ser-HPr when glucose is exhausted, the pyrophosphate concentration in the cells is lowered to 1 mM. In B. subtilis, this might be achieved by YvoE. This protein exhibits pyrophosphatase activity, and its gene is organized in an operon with hprK.

MALDI-PSD-MS analysis of the phosphorylation sites of caseinomacropeptide

Caseinomacropeptide (CMP) is a 64 amino acid polypeptide corresponding to κ-casein 106–169. CMP naturally exists in several forms due to extensive posttranslational modifications including glycosylation and phosphorylation. The aglycosylated, phosphorylated form of CMP has been shown to exhibit antibacterial activity. The aim of this study was to use matrix assisted laser desorption/ionization post source decay mass spectrometry (MALDI-PSD-MS) to identify the phosphorylation sites in the CMP sequence. CMP was isolated from a chymosin digest of casein by HPLC and then digested with endoproteinase Glu-C to generate peptides suitable for MALDI-PSD-MS analysis. This analysis showed that CMP is fully phosphorylated at Ser 149 and only partially phosphorylated at Ser 127. Dehydroalanyl residues corresponding to the phosphoserines of CMP were detected upon MALDI-PSD-MS analysis suggesting that the phosphoryl bond in phosphoserine is very labile during PSD analysis such that the phosphoryl group may be lost before backbone fragmentation.

A novel sphingophosphonolipid head group 1-hydroxy-2-aminoethyl phosphonate in Bdellovibrio stolpii.

Members of the bacterial genus Bdellovibrio include strains that are free-living, whereas others are known to invade and parasitize larger Gram-negative bacteria. The bacterium can synthesize several sphingophospholipid compounds including those with phosphoryl bonds as well as phosphonyl bonds. In the present study, the dominant sphingophosphonolipid component was isolated by column chromatography, and the long-chain bases, fatty acids, and polar head groups were identified by thin-layer and gas-liquid chromatographic procedures. The definitive structural identity of the sphingolipid was established by nuclear magnetic resonance and mass spectrometry of hydrolysis products and the intact compound. The compound was identified as N-2'-hydroxypentadecanoyl-2-amino-3,4-dihydroxyheptadecan-1-phosphono-(1-hydroxy-2-aminoethane).