The effect of surface charge balance on thermodynamic stability and kinetics of refolding of firefly Luciferase

( Khosrow Khalifeh ),( Bijan Ranjbar ),( Bagher Said Alipour ),( Saman Hosseinkhani ) 생화학분자생물학회(구 한국생화학분자생물학회) 2011 BMB Reports Vol.44 No.2

Thermodynamic stability and refolding kinetics of firefly luciferase and three representative mutants with depletion of negative charge on a flexible loop via substitution of Glu by Arg(ER mutant) or Lys (EK mutant) as well as insertion of another Arg in ER mutants (ERR mutant) was investigated. According to thermodynamic studies, structural stability of ERR and ER mutants are enhanced compared to WT protein, whereas, these mutants become prone to aggregation at higher temperatures. Accordingly, it was concluded that enhanced structural stability of mutants depends on more compactness of folded state, whereas aggregation at higher temperatures in mutants is due to weakening of intermolecular repulsive electrostatic interactions and increase of intermolecular hydrophobic interactions. Kinetic results indicate that early events of protein folding are accelerated in mutants. [BMB reports 2011; 44(2): 102-106]

Spinal Robotics in Adult Spinal Deformity Surgery: A Systematic Review

Kareem Khalifeh,Nolan J. Brown,Zach Pennington 대한척추신경외과학회 2024 Neurospine Vol.21 No.1

Spinal robotics have the potential to improve the consistency of outcomes in adult spinal deformity (ASD) surgery. The objective of this paper is to assess the accuracy of pedicle and S2 alar-iliac (S2AI) screws placed with robotic guidance in ASD patients. PubMed Central, Google Scholar, and an institutional library database were queried until May 2023. Articles were included if they described ASD correction via robotic guidance and pedicle and/or S2AI screw accuracy. Articles were excluded if they described pediatric/adolescent spinal deformity or included outcomes for both ASD and non-ASD patients without separating the data. Methodological quality was assessed using the Newcastle-Ottawa scale. Primary endpoints were pedicle screw accuracy based on the Gertzbein-Robbins Scale and self-reported accuracy percentages for S2AI screws. Data were extracted for patient demographics, operative details, and perioperative outcomes and assessed using descriptive statistics. Five studies comprising 138 patients were included (mean age 66.0 years; 85 females). A total of 1,508 screws were inserted using robotic assistance (51 S2AI screws). Two studies assessing pedicle screws reported clinically acceptable trajectory rates of 98.7% and 96.0%, respectively. Another study reported a pedicle screw accuracy rate of 95.5%. Three studies reported 100% accuracy across 51 total S2AI screws. Eight total complications and 4 reoperations were reported. Current evidence supports the application of robotics in ASD surgery as safe and effective for placement of both screw types. However, due to the paucity of data, a comprehensive assessment of its incremental benefit over other techniques cannot be made. Further work using expanded cohorts is merited.

Self-Regulation of Arousal on Attention in Iranian National Taekwondo Athletes

( Seyed Nemat Khalifeh ),( Bita Divsarnaz ),( Seyed Mohammad Pouladgar ) 국제태권도학회 2017 International Symposium for Taekwondo Studies Vol.2017 No.-

Purpose: The purpose of this study was to explore the effect of self-regulation of arousal through bio/neurofeedback training on attention in Iranian Taekwondo athletes. Methods: Sixteen elite male Taekwondo athletes with a minimum of three years’ experience competing at the international level (i.e. Taekwondo World Championships/Olympic Games) participated in the study. Participants were split into experimental and control group and completed a computer-based program that involved fifteen sessions of bio/neurofeedback training. The protocols manipulated participants’ physiological signs, such as heart and respiration rate, and brain activity as a way to teach self-regulation of arousal levels through computer-based feedback. The protocols were used with the aim of increasing heart rate variability, decreasing the rate of respiration, and promoting an effective brain wave ratio. To measure attention, the Advanced Integrated Visual and Auditory Continuous Performance Test (IVA-Advanced) was applied. Results: A significant difference was observed in auditory attention (t [7.36] = 3.58, p < 0.0), visual attention (t [7.48] = 4.42, p < 0.05), and total attention between the experimental and control groups (t [7.27] = 3.76, p < 0.05). Conclusions: The promotion of arousal level in physiological signs through bio/neurofeedback training enhanced the participants’ ability to maintain attention. Therefore, the self-regulatory methods of arousal, such as the one involved in the study, can be recommended as an approach to promote the self-regulation of athletes’ arousal and attention.

Design and synthesis of CuO@SiO2 multi-yolk@shell and its application as a new catalyst for CO2 fixation reaction under solventless condition

Maryam Rajabzadeh,Reza Khalifeh,Hossein Eshghi,Ali Hafizi 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.89 No.-

A new nanoreactor type structure composed of hollow mesoporous silica spheres and CuO nanoparticlesloaded inside the interior cavity of spheres has been designed and successfully prepared. The synthesismethod is proceed in a four step procedure by using carbon spheres as the hard template together with acoating of tetraethyl orthosilicate (TEOS) and cetyltrimethyl ammonium bromide (CTAB) mixture. Theobtained nanoreactors were characterized with FE-SEM, elemental mapping, TEM, XRD, BET, ICP and TPRanalysis. The CO2 fixation reaction is applied to evaluate the catalytic performance of the synthesizedCuO@SiO2 multi-yolk@shell catalyst. This catalyst exhibits superior activity in CO2 fixation reactions with96% yield in 4 h at low pressure. The catalyst demonstrates superb mechanical stability, high activity andis recovered for at least six times without loss of activity in CO2 fixation reaction, showing that this type ofnanoreactor could be applied as a promising material in advanced catalysis applications.

Ionic liquid functionalized graphene oxide for the adsorption of Ca2+ and Mg2+ ions from saline aqueous feed

Botagoz Zhuman,Hadil Abu Khalifeh,Ioannis Zuburtikudis,Mahendra Kumar,Hassan A. Arafat,Enas Nashef 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.5

The development of an efficient adsorbent for removal of Ca2+ and Mg2+ ions using ionic liquid (IL) (1-Ethyl-3-methylimidazolium amino acetate) functionalized graphene oxide (GO) (IL-GO) is reported. The formation of IL-GO adsorbent was confirmed by FTIR, Raman, TGA, TEM and SEM-EDX analysis. The loading of IL within the IL-GO adsorbent was found to be 39 wt%. A minimum amount of IL (∼2%) leached from IL-GO after continuous stirring in DI water for 24 h. The IL-GO adsorbent exhibited high adsorption capacity towards Ca2+ and Mg2+ ions and stable recovery without cross-contamination of the feed water. The structural integrity of IL-GO was preserved after functionalization and adsorption of Ca2+ and Mg2+ from aqueous solution. Adsorption kinetics results show that the adsorption rates of Ca2+ and Mg2+ follow a pseudo second-order kinetic model. Moreover, the adsorption data of both Ca2+ and Mg2+ on IL-GO is well fitted using the Langmuir isotherm, implying that active sites for adsorption are homogeneously distributed on the IL-GO surface. IL-GO adsorbent shows promise in the removal of Ca2+ and Mg2+ ions from saline water, as part of a pretreatment process in reverse osmosis (RO) desalination plants, to control the inorganic fouling of RO membranes. Finally, since the adsorption capacity of IL-GO for Ca2+ and Mg2+ has been found to be much greater than that for Na+, the developed adsorbent could be a very good candidate for the separation of monovalent and divalent cations from an aqueous feed.

The Electronic and Thermoelectric Properties of Si_1-xV_x Alloys from First Principles

Ramanathan, Amall Ahmed,Khalifeh, Jamil Mahmoud Korean Society of Microscopy 2017 Applied microscopy Vol.47 No.3

The effect of temperature and vanadium metal concentration on the electronic and thermoelectric properties of Si in the diamond cubic structure has been investigated using a combination of density functional theory simulations and the semi classical Boltzmann's theory. The BotzTrap code within the constant relaxation time approximation has been used to obtain the Seebeck coefficient and other transport properties of interest for alloys of the structure $Si_{1-x}V_x$, where x is 0, 0.125, 0.25, 0.375, and 0.5. The thermoelectric properties have been extracted for a temperature range of 300 K to 1,000 K. The general trend with V atom substitution for Si causes the Seeback coefficient to increase and the thermal conductivity to decrease for the various alloys. The optimum values are for $Si_5V_3$ and $Si_4V_4$ alloys for charge carrier concentrations of $10^{21}cm^{-3}$ in the mid temperature range of 500~800 K. This is a very desirable effect for a promising thermoelectric and the figure of merit ZT approaches 0.2 at 600 K for the p-type $Si_5V_3$ alloy.

Critical Role of Glu175 on Stability and Folding of Bacterial Luciferase: Stopped-flow Fluorescence Study

Shirazy, Najmeh Hadizadeh,Ranjbar, Bijan,Hosseinkhani, Saman,Khalifeh, Khosrow,Madvar, Ali Riahi,Naderi-Manesh, Hossein Korean Society for Biochemistry and Molecular Biol 2007 Journal of biochemistry and molecular biology Vol.40 No.4

Bacterial luciferase is a heterodimeric enzyme, which catalyzes the light emission reaction, utilizing reduced FMN (FMNH2), a long chain aliphatic aldehyde and $O_2$, to produce green-blue light. This enzyme can be readily classed as slow or fast decay based on their rate of luminescence decay in a single turnover. Mutation of Glu175 in $\alpha$ subunit to Gly converted slow decay Xenorhabdus Luminescence luciferase to fast decay one. The following studies revealed that changing the luciferase flexibility and lake of Glu-flavin interactions are responsible for the unusual kinetic properties of mutant enzyme. Optical and thermodynamics studies have caused a decrease in free energy and anisotropy of mutant enzyme. Moreover, the role of Glu175 in transition state of folding pathway by use of stopped-flow fluorescence technique has been studied which suggesting that Glu175 is not involved in transition state of folding and appears as surface residue of the nucleus or as a member of one of a few alternative folding nuclei. These results suggest that mutation of Glu175 to Gly extended the structure of Xenorhabdus Luminescence luciferase, locally.

Fabrication of Non-enzymatic Electrochemical Glucose Sensor Based on Nano-copper Oxide Micro Hollow-spheres

Zahra Haghparas,Zoheir Kordrostami,Mohsen Sorouri,Maryam Rajabzadeh,Reza Khalifeh 한국생물공학회 2020 Biotechnology and Bioprocess Engineering Vol.25 No.4

In the present study, an electrochemical glucose biosensor has been developed based on nano-copper oxide micro hollow spheres. The nano-copper oxide micro hollow spheres were synthesized via hydrothermal method using pluronic F-127 as a surfactant. For structural characterization of CuO hollow sphere structures, the scanning electron microscopy and X-ray diffraction spectroscopy were applied. The performance parameters of the sensor were improved by optimizing the modification process. The electrochemical characteristics of the proposed glucose biosensor were investigated by using cyclic voltammetry and chronoamperometry techniques in both 0.1 M and 1M NaOH solutions. The results revealed that the proposed electrode has a wide dynamic range from 1 μM to 11.50 mM for glucose detection at 0.1 M NaOH solution which covers two linear ranges from 1 μM to 3 mM and from 3 mM to 11.50 mM. The sensitivities of the two linear ranges were obtained as 25.0 ± 0.8 μA·mM-1·cm-2 and 13.6 ± 0.3 μA·mM-1·cm-2, respectively. An extremely wide linear range from 1 μM to 16 mM with a sensitivity of 35.2 ± 0.4 μA·mM-1·cm-2 was achieved for the 1 M NaOH solution. The sensor achieved a 1 μM practical lowest limit of detection which is an excellent low limit of detection at both NaOH concentrations compared to some important previously reported works. In addition, the good tolerance toward the interfering species and the satisfactory behavior in real sample analysis verified the promising performance of the proposed sensor.

Critical Role of Glu175 on Stability and Folding of Bacterial Luciferase: Stopped-flow Fluorescence Study

( Najmeh Hadizadeh Shirazy ),( Bijan Ranjbar ),( Saman Hosseinkhani ),( Khosrow Khalifeh ),( Ali Riahi Madvar ),( Hossein Naderi Manesh ) 생화학분자생물학회 2007 BMB Reports Vol.40 No.4

Literacy and Breast Cancer Prevention: a Population-Based Study from Iran

Harirchi, Iraj,Azary, Saeedeh,Montazeri, Ali,Mousavi, Seyed Mohsen,Sedighi, Zahra,Keshtmand, Gelavizh,Zarinkolah, Zahra,Soltani, S.M. Amin Khalifeh Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.8

Breast cancer is the most common cancer in women worldwide and the leading cause of death from cancer among women. Evidence suggests that early diagnosis and screening interventions might help to improve outcomes. This population-based study was conducted to determine breast cancer awareness and screening behavior among Iranian women and to examine its association with women's literacy. The study was carried out in two provinces, with 1,477,045 population, located in central and eastern part of Iran. Overall, 770 women were studied. Of these, 482 (62.7%) were literate and 287 (37.3%) were not. The results obtained from the data analysis indicated that there was a significant difference between literate and illiterate women. Further analysis of the data using logistic regression showed that literacy was an important contributing factor for breast cancer prevention behavior. The findings suggest that in order to improve women's health and breast cancer outcomes providing equal educational opportunities for women seems necessary.