Ahmed J

References (5)

Title : A thermotolerant and pH stable rhamnogalacturonan acetylesterase (CtPae12B), a family 12 carbohydrate esterase from Clostridium thermocellum with broad substrate specificity - Ahmed_2022_Int.J.Biol.Macromol__
Author(s) : Ahmed J , Kumar K , Goyal A
Ref : Int J Biol Macromol , : , 2022
Abstract : The gene encoding rhamnogalacturonan acetylesterase, CtPae12B from Clostridium thermocellum was cloned, expressed, purified and biochemically characterized. Purified CtPae12B was soluble and exhibited homogenous single band. Phylogenetically it was most closely related to an RGAE, YesT from B. subtilis. CtPae12B production was maximum with LB medium. CtPae12B showed optimal temperature, 65s degreesC and thermostability with half-life, 5.1sh at 80s degreesC. CtPae12B was alkaliphilic with optimal pH, 8.0, while it displayed stability at both acidic and alkaline pH ranges. Inhibition of CtPae12B activity by PMSF showed the importance of nucleophilic serine in the catalytic triad. The metal ions, chemical or chelating agents used, did not enhance CtPae12B activity, which was also corroborated by protein melting study. The enzymatic activity of CtPae12B remained unaffected by 5sM urea. CtPae12B showed broad substrate specificity as it displayed activity against a range of synthetic substrates showing highest V(max), 770sU/mg and K(m), 1.2smM with beta-D-gluco pentaacetate. CtPae12B could deacetylate both pectic and xylan substrates showing highest V(max), 770sU/mg and K(m), 13.4smg/mL with potato rhamnogalacturonan and V(max), 105sU/mg and K(m), 7.1smg/mL with acetylated birchwood xylan. The thermostability, pH stability and broad substrate specificity of CtPae12B makes it a versatile enzyme for industrial applications.
ESTHER : Ahmed_2022_Int.J.Biol.Macromol__
PubMedSearch : Ahmed_2022_Int.J.Biol.Macromol__
PubMedID: 36455821

Title : Computational and SAXS-based structure insights of pectin acetyl esterase (CtPae12B) of family 12 carbohydrate esterase from Clostridium thermocellum ATCC 27405 - Ahmed_2021_J.Biomol.Struct.Dyn__1
Author(s) : Ahmed J , Kumar K , Sharma K , Fontes C , Goyal A
Ref : J Biomol Struct Dyn , :1 , 2021
Abstract : Pectin is a complex form of polysaccharide and is composed of several structural components that require the concerted action of several pectinases for its complete degradation. In this study, in silico and solution structure of a pectin acetyl esterase (CtPae12B) of family 12 carbohydrate esterase (CE12) from Clostridium thermocellum was determined. The CtPae12B modelled structure, showed a new alpha/beta hydrolase fold, similar to the fold found in the crystal structures of its nearest homologues from CE12 family, which differed from alpha/beta hydrolase fold found in glycoside hydrolases. In the active site of CtPae12B, two loops (loop1 and loop6) play an important role in the formation of a catalytic triad Ser15-Asp187-His190, where Ser15 acts as a nucleophile. The structural stability of CtPae12B and its catalytic site was detected by performing molecular dynamic (MD) simulation which showed stable and compact conformation of the structure. Molecular docking method was employed to analyse the conformations of various suitable ligands docked at the active site of CtPae12B. The stability and structural specificity of the catalytic residues with the ligand, 4-nitrophenyl acetate (4-NPA) was confirmed by MD simulation of CtPae12B-4NPA docked complex. Moreover, it was found that the nucleophile Ser15, forms hydrophobic interaction with 4-NPA in the active site to complete covalent catalysis. Small angle X-ray scattering analysis of CtPae12B at 3 mg/mL displayed elongated, compact and monodispersed nature in solution. The ab initio derived dummy model showed that CtPae12B exists as a homotrimer at 3 mg/mL which was also confirmed by dynamic light scattering.Communicated by Ramaswamy H. Sarma.
ESTHER : Ahmed_2021_J.Biomol.Struct.Dyn__1
PubMedSearch : Ahmed_2021_J.Biomol.Struct.Dyn__1
PubMedID: 33860720

Title : Flavonoids as Prospective Neuroprotectants and Their Therapeutic Propensity in Aging Associated Neurological Disorders - Ayaz_2019_Front.Aging.Neurosci_11_155
Author(s) : Ayaz M , Sadiq A , Junaid M , Ullah F , Ovais M , Ullah I , Ahmed J , Shahid M
Ref : Front Aging Neurosci , 11 :155 , 2019
Abstract : Modern research has revealed that dietary consumption of flavonoids and flavonoids-rich foods significantly improve cognitive capabilities, inhibit or delay the senescence process and related neurodegenerative disorders including Alzheimer's disease (AD). The flavonoids rich foods such as green tea, cocoa, blue berry and other foods improve the various states of cognitive dysfunction, AD and dementia-like pathological alterations in different animal models. The mechanisms of flavonoids have been shown to be mediated through the inhibition of cholinesterases including acetylcholinesterase (AChE), and butyrylcholinesterase (BChE), beta-secretase (BACE1), free radicals and modulation of signaling pathways, that are implicated in cognitive and neuroprotective functions. Flavonoids interact with various signaling protein pathways like ERK and PI3-kinase/Akt and modulate their actions, thereby leading to beneficial neuroprotective effects. Moreover, they enhance vascular blood flow and instigate neurogenesis particularly in the hippocampus. Flavonoids also hamper the progression of pathological symptoms of neurodegenerative diseases by inhibiting neuronal apoptosis induced by neurotoxic substances including free radicals and beta-amyloid proteins (Abeta). All these protective mechanisms contribute to the maintenance of number, quality of neurons and their synaptic connectivity in the brain. Thus flavonoids can thwart the progression of age-related disorders and can be a potential source for the design and development of new drugs effective in cognitive disorders.
ESTHER : Ayaz_2019_Front.Aging.Neurosci_11_155
PubMedSearch : Ayaz_2019_Front.Aging.Neurosci_11_155
PubMedID: 31293414

Title : Neuroprotective and Anti-Aging Potentials of Essential Oils from Aromatic and Medicinal Plants - Ayaz_2017_Front.Aging.Neurosci_9_168
Author(s) : Ayaz M , Sadiq A , Junaid M , Ullah F , Subhan F , Ahmed J
Ref : Front Aging Neurosci , 9 :168 , 2017
Abstract : The use of essential oils (EOs) and their components is known since long in traditional medicine and aromatherapy for the management of various diseases, and is further increased in the recent times. The neuroprotective and anti-aging potentials of EOs and their possible mechanism of actions were evaluated by numerous researchers around the globe. Several clinically important EOs and their components from Nigella sativa, Acorus gramineus, Lavandula angustifolia, Eucalyptus globulus, Mentha piperita, Rosmarinus officinalis, Jasminum sambac, Piper nigrum and so many other plants are reported for neuroprotective effects. This review article was aimed to summarize the current finding on EOs tested against neurodegenerative disorders like Alzheimer disease (AD) and dementia. The effects of EOs on pathological targets of AD and dementia including amyloid deposition (Abeta), neurofibrillary tangles (NFTs), cholinergic hypofunction, oxidative stress and glutamatergic abnormalities were focused. Furthermore, effects of EOs on other neurological disorders including anxiety, depression, cognitive hypofunction epilepsy and convulsions were also evaluated in detail. In conclusion, EOs were effective on several pathological targets and have improved cognitive performance in animal models and human subjects. Thus, EOs can be developed as multi-potent agents against neurological disorders with better efficacy, safety and cost effectiveness.
ESTHER : Ayaz_2017_Front.Aging.Neurosci_9_168
PubMedSearch : Ayaz_2017_Front.Aging.Neurosci_9_168
PubMedID: 28611658

Title : Phenolic contents, antioxidant and anticholinesterase potentials of crude extract, subsequent fractions and crude saponins from Polygonum hydropiper L - Ayaz_2014_BMC.Complement.Altern.Med_14_145
Author(s) : Ayaz M , Junaid M , Ahmed J , Ullah F , Sadiq A , Ahmad S , Imran M
Ref : BMC Complement Altern Med , 14 :145 , 2014
Abstract : BACKGROUND: We investigated Polygonum hydropiper L. (P. hydropiper) for phenolic contents, antioxidant, anticholinesterase activities, in an attempt to rationalize its use in neurological disorders.
METHODS: Plant crude extract (Ph.Cr), its subsequent fractions: n-hexane (Ph.Hex), chloroform (Ph.Chf), ethyl acetate (Ph.EtAc), n-Butanol (Ph.Bt), aqueous (Ph.Aq) and saponins (Ph.Sp) were evaluated for 1,1-diphenyl,2-picrylhydrazyl (DPPH), 2,2-azinobis[3-ethylbenzthiazoline]-6-sulfonic acid (ABTS) free radical scavenging potential. Further, acetylcholinesterase (AChE) & butyrylcholinesterase (BChE) inhibitory activities were performed using Ellman's assay. Moreover, total phenolic contents of plant extracts were determined and expressed in mg of gallic acid equivalent per gram of dry sample (mg GAE/g dry weight).
RESULTS: Among different fractions, Ph.Cr (90.82), Ph.Chf (178.16), Ph.EtAc (203.44) and Ph.Bt (153.61) exhibited high phenolic contents. All fractions showed concentration dependent DPPH scavenging activity, with Ph.EtAc 71.33% (IC50 15 mug/ml), Ph.Bt 71.40% (IC50 3 mug/ml) and Ph.Sp 71.40% (IC50 35 mug/ml) were most potent. The plant extracts exhibited high ABTS scavenging ability i.e. Ph.Bt (91.03%), Ph.EtAc (90.56%), Ph.Sp (90.84%), Ph.Aq (90.56%) with IC50 < 0.01 mug/ml. All fractions showed moderate to high AChE inhibitory activity as; Ph.Cr, 86.87% (IC50 330 mug/ml), Ph.Hex, 87.49% (IC50 35 mug/ml), Ph.Chf, 84.76% (IC50 55 mug/ml), Ph.Sp, 87.58% (IC50 108 mug/ml) and Ph.EtAc 79.95% (IC50 310 mug/ml) at 1 mg/ml). Furthermore the BChE inhibitory activity was most prominent in Ph.Hex 90.30% (IC50 40 mug/ml), Ph.Chf 85.94% (IC50 215 mug/ml), Ph.Aq 87.62% (IC50 3 mug/ml) and Ph.EtAc 81.01% (IC50 395 mug/ml) fractions.
CONCLUSIONS: In this study, for the first time, we determined phenolic contents, isolated crude saponins, investigated antioxidant and anticholinestrase potential of P. hydropiper extracts. The results indicate that P. hydropiper is enriched with potent bioactive compounds and warrant further investigation by isolation and structural elucidation to find novel and affordable compounds for the treatment of various neurological disorders.
ESTHER : Ayaz_2014_BMC.Complement.Altern.Med_14_145
PubMedSearch : Ayaz_2014_BMC.Complement.Altern.Med_14_145
PubMedID: 24884823