Phosphate Monoesters Research Articles

Phosphate diester utilization by marine diazotrophs Trichodesmium erythraeum and Crocosphaera watsonii

In the phosphate-depleted oligotrophic ocean, microbes utilize various dissolved organic phosphorus (P) compounds as alternative P sources, using enzymes such as alkaline phosphatases. However, knowledge of such P acquisition mechanisms is limited, especially in association with the physiology of nitrogen-fixing organisms, which play a substantial role in marine biogeochemical cycling. We show that nonaxenic clonal cultures of 2 oceanic diazotrophs,Trichodesmium erythraeumandCrocosphaera watsonii, have the ability to utilize phosphate diester as their sole P source, using a model artificial compound—bis-p-nitrophenyl phosphate (bisNPP). Although both diazotroph cultures likely preferred phosphate monoester to diester, the expressed diesterase activity was theoretically sufficient to fulfill their P demands, and they showed significant growth in bisNPP-added media. Interestingly, a distinct difference in their growth trends was observed, with faster onset of growth byC. watsoniiand delayed onset of growth byT. erythraeum. This indicates that theC. watsoniiconsortium can effectively and rapidly assimilatein situdiesters as alternative P sources in the field. Nonetheless, when considering the poor bisNPP utilization reported from other marine phytoplankton taxa, our results indicate that the utilization of particular diester compounds is a notable and advantageous strategy for both diazotroph consortia to alleviate P limitation in the oligotrophic ocean.

31P-NMR Metabolomics Revealed Species-Specific Use of Phosphorous in Trees of a French Guiana Rainforest.

Productivity of tropical lowland moist forests is often limited by availability and functional allocation of phosphorus (P) that drives competition among tree species and becomes a key factor in determining forestall community diversity. We used non-target 31P-NMR metabolic profiling to study the foliar P-metabolism of trees of a French Guiana rainforest. The objective was to test the hypotheses that P-use is species-specific, and that species diversity relates to species P-use and concentrations of P-containing compounds, including inorganic phosphates, orthophosphate monoesters and diesters, phosphonates and organic polyphosphates. We found that tree species explained the 59% of variance in 31P-NMR metabolite profiling of leaves. A principal component analysis showed that tree species were separated along PC 1 and PC 2 of detected P-containing compounds, which represented a continuum going from high concentrations of metabolites related to non-active P and P-storage, low total P concentrations and high N:P ratios, to high concentrations of P-containing metabolites related to energy and anabolic metabolism, high total P concentrations and low N:P ratios. These results highlight the species-specific use of P and the existence of species-specific P-use niches that are driven by the distinct species-specific position in a continuum in the P-allocation from P-storage compounds to P-containing molecules related to energy and anabolic metabolism.

Design and synthesis of analogues of the sphingosine-1-phosphate receptor 1 agonist IMMH001 with improved phosphorylation rate in human blood

IMMH001, which is a prodrug for sphingosine-1-phosphate receptor 1 (S1P1) agonist, is converted to the active form, its monophosphate ester (S)-IMMH001-P, by sphingosine kinase 1 (SphK1) and sphingosine kinase 2 (SphK2) in vivo. In this study, we designed head-piece-modified analogues of IMMH001 based on structural information and prepared them with an efficient modular synthetic strategy. The analogues showed higher phosphorylation rates in human blood than the parent compound. These results indicated that the pro-R hydroxymethyl in the head-piece-moiety of IMMH001 prevents the pro-S hydroxymethyl from being phosphorylated by the kinase and ATP. The analogues may have better therapeutic potential.

Immobilization of agricultural phosphorus in temperate floodplain soils of Illinois, USA

Nutrient losses from Mississippi watersheds degrade downstream water bodies. As forested floodplains intercept agricultural drainage waters, a limiting nutrient like phosphorus (P) could potentially be sequestered in forest soils, reducing P loss to the Gulf of Mexico. Thus far, the role of temperate deciduous floodplain soils for P has not been extensively investigated in the Midwestern United States. The objective of this study was to investigate the buffering capacity of P in floodplain soils using soil biochemical chemical assays, 31P nuclear magnetic resonance spectroscopy (NMR) and P K-edge X-ray absorption near edge structure spectroscopy (XANES). Phosphorus reaction dynamics were compared between floodplains and surrounding upland soils in east-central Illinois, USA. Total organic P was significantly greater in the floodplain (277.27 ± 159.51 mg kg−1) than that in the upland (113.04 ± 74.88 mg kg−1), illustrating its buffering capacity. Notably, microbial biomass P (averaged 13.08 mg kg−1) was greater in the floodplain than that in the upland. The results of 31P NMR analysis showed the presence of organic P (e.g., orthophosphate monoesters) and orthophosphate. The P K-edge XANES analysis shows that these inorganic and organic P species are predominantly adsorbed in calcite and precipitated as calcium phosphate in floodplain soils. These findings suggest that temperate deciduous floodplain soils have a great potential to immobilize agricultural P in the Upper Mississippi watershed.

Zeta potential changing nanoemulsions based on phosphate moiety cleavage of a PEGylated surfactant

The aim of this study was to develop and evaluate a zeta potential changing nanoemulsion (NE) containing polyoxyethylene (9) nonylphenol monophosphate ester (PNPP) as emulsifier.2% (v/v) of PNPP and 0.18% (5 μM) of cetyltrimethylammonium bromide (CTAB) were incorporated into the lipophilic NE preconcentrate (PEG-40 castor oil, glyceryl tricaprylate/tricaprate, propylene glycol dicaprylocaprate, propylene glycol monolaurate, highly purified diethylene glycol monoethyl ether; 20/20/10/30/20, v/v). After diluting the lipophilic preconcentrate, resulting NE was analyzed regarding droplet size, polydispersity index (PDI), storage stability and zeta potential change after incubation with intestinal alkaline phosphatase (IAP). Phosphate release due to cleavage by IAP was quantified by malachite green assay and toxicity as well as cellular uptake behavior on Caco-2 cells was determined. The NE containing PNPP and CTAB displayed a droplet size of 113 nm and a PDI of 0.20. It was stable over 4 h. A zeta potential change from −33.7 to +8.2 mV was observed due to cleavage of phosphate groups by isolated IAP. PNPP could be identified as non-toxic up to concentrations of 0.01% (v/v). Furthermore, an enhanced cellular uptake of the NE changing its zeta potential on Caco-2 cells was determined. Therefore, PNPP seems to be a promising tool for the development of zeta potential changing NE.

Ferrihydrite Transformation Impacted by Coprecipitation of Phytic Acid.

Phytic acid is a common phosphate monoester that is present in soils due to the deposition of plant-derived materials. Thus far, its interaction with dissolved Fe and Fe minerals has not been as extensively investigated as phosphate, although it is expected be highly reactive due to its multiple phosphate functional groups. In this study, the effects of phytic acid on the formation of iron oxyhydroxide was investigated at near neutral pH as a function of the phytic acid/Fe ratio (0.05-0.5) and aging time using zeta potential measurements, X-ray diffraction, Fe K-edge X-ray absorption spectroscopy, and scanning electron transmission spectroscopy. It was found that an iron(III) phytate-like precipitate was formed when the phytic acid/Fe ratio was as low as 0.05. On increasing the ratio to 0.5, the quantity of iron(III) phytate-like precipitate increased to ∼60% in the ferrihydrite background. Interestingly, 10 month aging at 22 °C or hydrothermal treatment at 70 °C for 60 h did not transform the background ferrihydrite into goethite or hematite, suggesting the adsorbed phytic acid played an important role in inhibiting the transformation of ferrihydrite. The adsorption and incorporation of phytic acid into the Fe(III)O6 polymers should be useful in understanding the complex phosphorus, iron, and hard acid chemistry in a terrestrial environment.

Characterization of water-soluble esters of nitrobenzoxadiazole-based GSTP1-1 inhibitors for cancer treatment

The 7-nitrobenzo[c][1,2,5]oxadiazole (NBD) derivative NBDHEX (compound 1) and its analogue MC3181 (compound 2) have been found to be potent inhibitors of tumor cell growth in vitro and therapeutically active and safe in mice bearing human melanoma xenografts. To enhance the aqueous solubility of these compounds, we synthesized the hemisuccinate of 1 (compound 3) and the phosphate monoesters of 1 and 2 (compound 4 and 5, respectively). These novel NBD derivatives displayed a solubility in the conventional phosphate-buffered saline up to 150-fold higher than that of 1, and up to 4-fold higher than that of 2. Notably, solubility of phosphates 4 and 5 in a potassium phosphate buffer at pH 7.4, was up to 500-fold higher than that of 1, and ~10-fold higher than that of 2. Compounds 3–5 retained high cytotoxicity towards cultured human melanoma and osteosarcoma cells and were cleaved in vitro by both human and murine hydrolases, thus releasing the corresponding parent compound (i.e., 1 or 2). Interestingly, esters 3–5 displayed high inhibitory activity towards the glutathione transferase (GST) isoform GSTP1-1 and showed a reactivity towards reduced glutathione comparable to that of the respective parent compound. Finally, both 4 and 5 were safe and effective when administered intravenously or orally as an aqueous solution to mice xenografted with A375 human melanoma tumors. Collectively, these results and the previously observed synergistic interaction between 1 and 2 and various approved anticancer drugs, suggest the possible utility of phosphates 4 and 5 as single agents and in combination regimens in cancers with unmet medical need, including melanoma.

Phosphorus speciation during anaerobic digestion and subsequent solid/liquid separation

This study aims to investigate the effect of anaerobic digestion (AD) on P species and how the different species are distributed in the digestate and digestate fractions, i.e. liquid and solid fractions. To do so, six full scale AD plants were used in this work and representative biomass samples were collected for investigation. P fractionation proceeded by adopting fractionation protocols consisting in step-by-step extraction with different solvents, (i.e. NaHCO3, HCl and NaOH-EDTA). Subsequently P species in the different fractions were identified by using 31PNMR. On average, AD did not substantially affect P speciation that depended on the P-fraction content of feeds. A high NaHCO3 fraction content in the ingestate determined, also, a high content of this fraction in the digestate, with consequently lower contents of both P-HCl and P-NaOH-EDTA, i.e. digestate P-fraction contents represented an inheritance of P speciation in the ingestate. A feed effect was observed in single plants. Highest pig/cow slurry content in the feeds seemed to decrease readily soluble P (extracted with NaHCO3) content and increased P associated with both organic matter and amorphous Fe/Al in the digestate. Again, using a large amount of digestate in the feed increased P-soluble content in the digestate. 31P NMR analyses revealed that inorganic P compounds dominated the spectra of all biomasses and fractions, with orthophosphate as the predominant species. When present, organic phosphorus compounds were typically represented by monophosphate esters, DNA and phospholipids, with a predominance of monophosphate esters.

Alkaline phosphatase activity as a biochemical biomarker in aqua-toxicological studies

Alkaline phosphatase (ALP) is a glycoprotein with a metallophosphatase structure that catalyzes the hydrolysis of monophosphate esters of biomolecule esters at alkaline pH. ALP activity is a useful bioindicator to assess the physiological health of cellular membranes, cell growth, apoptosis and cell migration, cellular metabolic status, hepatocyte function, and detoxification activity in hepatocytes. ALP activity is detected in a colorimetric method using the para-nitrophenyl phosphate substrate (p-NPP) at a wavelength of 405 nm in biological samples. Cell hemolysis, especially erythrocytes; increased levels of sex hormones and corticosteroids, biological infections, and poor nutrition can adversely affect ALP activity.

Synthesis, crystal structure, phosphate hydrolysis activity and antibacterial activity of macrocyclic dinuclear Zn(II) complex with benzyl pendant-arms

A new macrocyclic dinuclear Zn(II) complex is synthesized by the cyclocondensation between 3,3’-(ethane-1,2-diylbis (benzylazanediyl))bis(methylene) bis (2-hydroxy-5-methyl-benzaldehyde) and 1,3-diaminopropane and the subsequent with zinc salts. The as-prepared complex is characterized by elemental analysis, FT-IR, ES-MS and single crystal X-ray diffraction. The complex consists of one independent molecular unit of [Zn2(μ-OAC)L]+ ClO4− and two water molecules with one on a symmetry element. Four of these units collectively form two pairs of dinuclear complex units of [Zn2(μ-OAc)L]+ with one unit sharing two perchlorate ions and one water molecule and the other unit sharing two perchlorate ions and one symmetry equivalent water molecule. Each zinc(II) ion exhibits a slightly distorted square pyramidal geometry. Two Zn atoms are bridged by two oxygen atoms of an acetate anion and two phenolic O atoms. The Zn–Zn distance is 2.951 Å. An ordered two-dimensional network is formed by weak intermolecular interactions in the crystal structure of the complex. The phosphate ester hydrolysis activity and the antibacterial activity of the complex are studied. The results showed that the synthesized complex has an efficient catalytic activity of phosphoester bond cleavage and the potential to inhibit the growth of E. coli. The optimum catalytic rate constant (kcat) at pH 7.8 for the hydrolysis of 4-nitrophenyl phosphate disodium salt hexahydrate (pNPP) by the synthesized complex is 2.98 × 10−4 s−1, and 105 times faster than that the spontaneous hydrolysis of the phosphate monoester.

S1P1-selective agonist prodrug IMMH002 is phosphorylated in rats to form an S-configured enantiomer: Synthesis, verification, and biological activity of the in vivo active metabolite

IMMH002 (1), a prodrug for a sphingosine-1-phosphate receptor 1 (S1P1) agonist, is converted to the monophosphate ester, which has an immunomodulatory effect. Starting from prochiral amino alcohol 1, racemic and enantiomerically pure phosphates of 1 were synthesized. Pure enantiomers were obtained after the chiral resolution of the key intermediate by chiral high-performance liquid chromatography and the absolute configuration was determined by circular dichroism. In the in vitro homogeneous time-resolved fluorescence-IP1 functional assay, the (S)-enantiomer showed much higher S1P1 activity and selectivity than the (R)-enantiomer. In the pharmacokinetic study, the ex vivo o-phthaldialdehyde derivatization protocol showed that the phosphate of 1 in rats was the S-configured enantiomer with >99% enantiomeric excess.

Developing a Cost-Effective Bioassay to Detect Alkaline Phosphatase Activity and Generating White Light Emission from a Single Nano-Assembly by Conjugating Vitamin B6 Cofactors with Lysozyme-Stabilized Fluorescent Gold Nanoclusters

In this work, lysozyme-stabilized fluorescent gold nanoclusters (Lyso-AuNCs) and pyridoxal 5′-phosphate (PLP) as a monophosphate ester substrate were used to develop a highly selective and cost-eff...

Phosphate microbial mineralization consolidation of waste incineration fly ash and removal of lead ions.

This paper proposes a green environment-friendly Bacillus subtilis to mineralize and consolidate waste incineration fly ash and heavy metal cations, and there is no harmful by-product in the mineralization process. Different phosphate products can be prepared, and are more stable than the microbially-induced carbonate precipitation (MICP) in nature. Typical heavy metal oxides were mainly PbO, ZnO, CdO, NiO, CuO and Cr2O3 in the chemical composition of waste incineration fly ash. Microstructure and chemical composition of waste incineration fly ash before and after treatment were characterized by powder X-ray diffraction (XRD) analysis and scanning electron microscopy. Scanning electron microscopy (SEM) images showed that the morphology of the Bacillus subtilis was mainly a rod-like structure. The optimal hydrolysis dosage of the organic phosphate monoester sodium salt was 0.2mol in the bacterial solution (1L, 20g/L). The optimum required mass of the bacterial powder was 15g/kg in treatment process of the waste incineration fly ash. The initial concentration of lead ions was 40.28mg/L in waste incineration fly ash solution. After the optimum dosage treatment, the removal efficiency of lead ions was 78.15%, 79.64%, 77.70% and 80.14% when curing time was 1, 2, 4 and 6d, respectively. The waste incineration fly ash had a Shore hardness of 22 after the optimum amount of bacterial liquid treatment. Results of wind erosion test showed that the wind erosion rate of waste incineration fly ash was 2.6, 0, 0, 0, 0 and 0g/h when blank group, deionized water, 100, 200, 300 and 400mL of bacterial solutions treated, respectively. The bio-mineralization method provides an approach for the safe disposal of heavy metals in the contaminated areas of tailings, electroplating sewage, waste incineration plants, and so on.

Insight into effects of organic and inorganic phosphorus speciations on phosphorus removal efficiency in secondary effluent.

Most previous studies of phosphorus (P) removal focused on investigation of the soluble, and particulate P, but ignoring the difference between organic and inorganic P. In this study, the effects of various flocculants, namely polyacrylamide (PAM) and polyaluminum chloride (PAC), on flocculation efficiency in different P speciations (organic and inorganic P) were investigated. A modified method to differentiate between organic and inorganic P content in secondary effluent samples was developed. The results showed that P speciation based on organic/inorganic P (Pearson's correlation R= 0.915, p< 0.05) was more effective than those based on soluble/particulate P (p> 0.05) in evaluating the P content in secondary effluents. The liquid 31P nuclear magnetic resonance measurements results indicated that PAM was more effective in removing organic P (phosphonates and orthophosphate monoesters) rather than inorganic P. However, PAC was more effective in removing inorganic P (particularly orthophosphate) rather than organic P. Based on the modeled results of a response surface methodology (RSM), doses of PAM and PAC were optimized for secondary effluent containing different amounts of organic and inorganic P from the two typical wastewater treatment plants (WWTPs) in Wuhan city, China.

Catalytic Chemoselective O-Phosphorylation of Alcohols

Phosphorylation of alcohols is a fundamentally important reaction in both life science and physical science. Product phosphate monoesters play key roles in living organisms, natural products, pharmaceuticals, and organic materials. Most of the chemical methods to date for synthesizing phosphate monoesters, however, require multistep sequences or are limited to specific types of substrates possibly due to harsh conditions. An alternative way to enable the simple production of phosphate monoesters from highly functionalized precursor alcohols is, thus, highly desired. We report herein a catalytic phosphorylation of alcohols with high functional group tolerance using tetrabutylammonium hydrogen sulfate (TBAHS) and phosphoenolpyruvic acid monopotassium salt (PEP-K) as the catalyst and phosphoryl donor, respectively. This method enables the direct introduction of a nonprotected phosphate group to the hydroxy group of a diverse menu of alcohol substrates, including functionalized small molecules, carbohydrates, and unprotected peptides. Nuclear magnetic resonance, mass spectrometric, and density functional theory analyses suggest that an unprecedented mixed anhydride species, generated from PEP-K and TBAHS, acts as an active phosphoryl donor in this reaction. This operationally simple and chemoselective catalytic phosphorylation allows for the efficient production of densely functionalized O-phosphorylated compounds, which are useful in diverse fields including biology and medicine.

Restraint of enzymolysis and photolysis of organic phosphorus and pyrophosphate using synthetic zeolite with humic acid and lanthanum

Although phosphorus (P)-removing materials have been widely used to immobilize orthophosphate in aquatic ecosystems, the immobilization of organic phosphorus (OP) and pyrophosphate (PP) remains unclear. In this study, a unique OP/PP-immobilizing synthetic zeolite loaded with humic acid (HA) and La(OH)3 nanorod composite (ZHLA) is synthesized, and OP/PP-immobilization is examined by means of enzymolysis and photolysis. The results indicate that OP and PP could not be photodegraded into PO43− under natural conditions. Although OP could be degraded into PO43− by enhanced Fenton’s reagent, La3+ and HA could protect OP and PP from degradation. As a result of the colloidal coagulation and photocatalysis of La(OH)3, the activity of phosphatase could be reduced. The PP and phytate become resistant to enzymolysis through the formation of stable HA–La–PP/phytate or La–PP/phytate chelates. However, labile monoester phosphate could not form stable chelates resisting to enzymolysis. This labile monoester phosphate is hydrolyzed into PO43− and thereafter immobilized by ZHLA, which is the main pathway to achieve permanent immobilization. Most release-sensitive P fractions are transferred to the stable P fraction after ZHLA application. The ZHLA is demonstrated to be an economical and effective P-immobilization material and has high potential as a commercial sediment-capping product for eutrophication control.

Missed atmospheric organic phosphorus emitted by terrestrial plants, part 2: Experiment of volatile phosphorus

The emission and deposition of global atmospheric phosphorus (P) have long been considered unbalanced, and primary biogenic aerosol particles (PBAP) and phosphine (PH3) are considered to be the only atmospheric P sources from the ecosystem. In this work, we found and quantified volatile organic phosphorus (VOP) emissions from plants unaccounted for in previous studies. In a greenhouse in which lemons were cultivated, the atmospheric total phosphorus (TP) concentration of particulate matter (PM) was 41.8% higher than that in a greenhouse containing only soil, and the proportion of organic phosphorus (OP) in TP was doubled. 31P nuclear magnetic resonance tests (31P-NMR) of PM showed that phosphate monoesters were the main components contributed by plants in both the greenhouse and at an outside observation site. Atmospheric gaseous P was directly measured to be 1–2 orders of magnitude lower than P in PM but appeared to double during plant growing seasons relative to other months. Bag-sampling and gas chromatography mass spectrometry (GCMS) tests showed that the gaseous P emitted by plants in the greenhouse was triethyl phosphate. VOP might be an important component of atmospheric P that has been underestimated in previous studies.

Catalytic promiscuity of two novel cobalt(III) complexes derived from redox non-innocent Schiff base ligands: Unraveling the role of methyl groups in the ligand backbone on catalytic efficiency

Two Schiff base ligands namely (E)-4-bromo-2-(((1-hydroxy-2-methylpropan-2-yl)imino)methyl)-6-methoxyphenol(H2L1) and (E)-4-bromo-2-(((2-hydroxyethyl)imino)methyl)-6-methoxyphenol (H2L2) were designed and synthesized by varying methyl groups to prepare cobalt(III) complexes [Co(HL1)(L1)](1) and [Co(HL2)(L2)](2) using cobalt(II) acetate as metal precursor. Complexes 1 and 2 were characterized by usual physicochemical techniques and solid state structure of complex 2 was determined by X-Ray crystal structure analysis. The electrospray ionization-mass spectrometry (ESI-MS) analysis proved that complexes 1 and 2 were present as mononuclear entity in solution phase. The newly synthesized complexes were used to exploit their catalytic promiscuity. Catecholase like activity of both complexes 1 and 2 was carried out in N, N-dimethylformamide (DMF) medium using 3,5-di-tert-butyl catechol (3,5-DTBC) as model substrate (substrate : complex = 100:1) and the rate of the activity followed the trend, 1 > 2. Phosphatase like activity was studied by using disodium salt of 4-nitrophenylphosphate (4-NPP) as model substrate in DMF-H2O (substrate: complex = 20:1) mixture, indicating that the complexes were enormously accelerated the rate of phosphate monoester hydrolysis and the rate of the activity followed the reverse trend of catecholase like activity i.e.2 > 1. The role of methyl groups in the ligand backbone of H2L1 is supposed to be the determining factor to differentiate the catalytic efficiency of complexes 1 and 2 and the experimental observation has been supported by DFT calculations.

Photo-induced phosphate release during sediment resuspension in shallow lakes: A potential positive feedback mechanism of eutrophication

Dissolved phosphate (Pi) can be released during resuspended sediments exposed to sunlight. However, the significance of this phenomenon in the process of eutrophication is not clear. In this study, the behavior of photo-induced Pi release during sediment resuspension in shallow lakes with the different trophic states was investigated. The amount of photo-induced Pi release in the sediment resuspension from Lake Liangzi, Lake Dong, Lake Tangxun and Lake Longyang in China was 0.013, 0.019, 0.032, and 0.048 mg/L, respectively, and increased as the trophic states of the lakes increased. The results of phosphorus speciation analysis showed that the phosphate monoester in the particulate phosphorus is the organic phosphorus species participated in the photochemical reaction. The steady-state concentration of hydroxyl radical (OH) in the sediment resuspension also increased along with the trophic states of lakes increased and dissolved organic matter (DOM), nitrate, and Fe3+ presented in sediment resuspension were the main photosensitizers for OH production. All these results indicate that the increase of trophic states of lakes leads to the accumulation of organic phosphorus and OH, resulting in more dissolved phosphate photo-released, which accelerate the eutrophication process in a form of positive feedback.

In Silico Identification of Probable Drug and Vaccine Candidates Against Antibiotic-Resistant Acinetobacter baumannii.

Acinetobacter baumannii is known as a Gram-negative bacterium that has become one of the most important health problems due to antibiotic resistance. Today, numerous efforts are being made to find new antibiotics against this nosocomial pathogen. As an alternative solution, finding bacterial target(s), necessary for survival and spread of most resistant strains, can be a benefit exploited in drug and vaccine design. In this study, a list of extensive drug-resistant and carbapenem-resistant (multidrug resistant) A. bumannii strains with complete sequencing of genome were prepared and common hypothetical proteins (HPs) composed of more than 200 amino acids were selected. Then, a number of bioinformatics tools were combined for functional assignments of HPs using their sequence. Overall, among 18 in silico investigated proteins, the results showed that 7 proteins implicated in transcriptional regulation, pilus assembly, protein catabolism, fatty acid biosynthesis, adhesion, urea catalysis, and hydrolysis of phosphate monoesters have theoretical potential of involvement in successful survival and pathogenesis of A. baumannii. In addition, immunological analyses with prediction softwares indicated 4 HPs to be probable vaccine candidates. The outcome of this work will be helpful to find novel vaccine design candidates and therapeutic targets for A. baumannii through experimental investigations.