Asha Parmar

Sardar Patel University, Vallabh Vidhyanagar, Gujarāt, India

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Publications (11)31.82 Total impact

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    ABSTRACT: Alzheimer's disease (AD) represents a neurological disorder, which is caused by enzymatic degradation of an amyloid precursor protein into short peptide fragments that undergo association to form insoluble plaques. Preliminary studies suggest that cyanobacterial extracts, especially the light-harvesting protein phycocyanin, may provide a means to control the progression of the disease. However, the molecular mechanism of disease control remains elusive. In the present study, intact hexameric phycocyanin was isolated and crystallized from the cyanobacterium Leptolyngbya sp. N62DM, and the structure was solved to a resolution of 2.6 Å. Molecular docking studies show that the phycocyanin αβ-dimer interacts with the enzyme β-secretase, which catalyzes the proteolysis of the amyloid precursor protein to form plaques. The molecular docking studies suggest that the interaction between phycocyanin and β-secretase is energetically more favorable than previously reported inhibitor-β-secretase interactions. Transgenic Caenorhabditis elegans worms, with a genotype to serve as an AD-model, were significantly protected by phycocyanin. Therefore, the present study provides a novel structure-based molecular mechanism of phycocyanin-mediated therapy against AD.
    No preview · Article · Feb 2014 · CNS & neurological disorders drug targets
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    Dataset: 53 ABB
    Khalid Anwer · Asha Parmar · Safikur Rahman · Avani Kaushal · Datta Madamwar · Asimul Islam · Md Imtaiyaz · Faizan Ahmad · K Anwer · A Parmar · S Rahman · A Kaushal · D Madamwar · A Islam · F Ahmad

    Full-text · Dataset · Jan 2014
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    ABSTRACT: Folding and stability studies on C-PE and its natural N-terminal truncant, Archives of Biochemistry and Biophysics (2014), doi: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
    Full-text · Article · Jan 2014 · Archives of Biochemistry and Biophysics
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    ABSTRACT: Complementary chromatic adaptation, a photomorphogenetic response, known to occur in many cyanobacteria, enables them to efficiently absorb prevalent wavelengths of light in the environment. In the present study, we have described the influence of light on phycobiliprotein production in three marine phycoerythrin producing cyanobacterial cultures, namely, Lyngbya sp. A09DM, Phormidium sp. A27DM and Halomicronema sp. A32DM. A comparative study (UV-visible overlay spectra and SDS-PAGE analyses) of phycobiliproteins purified from all the three cultures grown in white, yellow, red and green lights has been confirmed. White light was taken as control. Red and green lights were taken to check their effect on phycocyanin and phycoerythrin production, respectively. Yellow light was studied as its wavelength falls in between green and red light. Lyngbya sp. A09DM was found to be the best chromatically adapting cyanobacterium followed by Halomicronema sp. A32DM. These two cultures can be placed in group III chromatic adaptors. Phormidium sp. A27DM was the least chromatically adapting culture and can be placed in group II chromatic adaptors. The study signifies that even light plays an important role along with nutrient availability in adapting cultures to changing environmental conditions.
    No preview · Article · Jun 2013 · Acta Physiologiae Plantarum
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    ABSTRACT: Two thermotolerant cyanobacterial strains N9DM I and N9DM II were collected from Tuwa geothermal spring, Panchmahal, Gujarat, India, from different wells having temperature 30 +/- 2 degrees C and 55 +/- 2 degrees C respectively. Analysis of 16S rRNA gene sequence revealed that both the strains were nearest neighbour of Oscillatoria sp. In addition to high temperature tolerance Oscillatoria N9Dm sp. changes phycobilisome rod pigmentation as exposed to various temperatures. Oscillatoria N9DM sp. produces phycoerythrin (PE) and phycocyanin (PC) at 30 +/- 2 degrees C and 55 +/- 2 degrees C, respectively whereas at intermediate temperature (42 +/- 2 degrees C) it produced phycoerythrocyanin (PEC). Moreover reverted cultures (normally grown at 55 +/- 2 degrees C but now sub-cultured and grown at 30 +/- 2 degrees C) started producing PE. Furthermore, Oscillatoria N9DM sp. produced PE, PC and PEC in white, red and yellow light respectively and it showed direct correlation to different proteins produced at various temperatures. To best of our knowledge, this is the first report describing correlation of temperature and its effect on the phycobiliprotein production. This study for the first time also tried to explain that thermo-adaptation might have been evolved along with complementary chromatic adaptation (CCA) in certain thermotolerant cyanobacteria where fluctuation of temperature was prevalent throughout the year.
    Full-text · Article · Dec 2012 · PROCESS BIOCHEMISTRY
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    ABSTRACT: In this study, we describe a series of experiments presenting the biochemical evidence for the cleavage of an intact phycoerythrin (� and � subunits) to phycoerythrin with only fragmented �-subunit, which is also functional, in Phormidium sp. A27DM. Culture, whether grown in different conditions (static or sparging) or in medium with different pH, produced truncated phycoerythrin. This indicated that the growth conditions or pH of medium did not lead to cleavage of phycoerythrin. Culture when grown in the medium lacking NaNO3 started producing truncated phycoerythrin after 9 days of growth only, thus proving that nitrogen depletion was playing a role in phycoerythrin cleavage. In vivo and in vitro experiments with different proteases also resulted in production of truncated phycoerythrin. And on the addition of different protease inhibitors intact phycoerythrin formation was taking place even after 60 days of growth, thus indicating the possible role of proteases in phycoerythrin cleavage. Moreover, purified intact PE when stored at 4 ◦C also gets cleaved to 14 kDa fragment. However, when glacial acetic acid was added to phycoerythrin no cleavage was observed even after 4 months of storage. The events indicate that production of truncated PE is meant for continuing the absorption of light under stress conditions.
    No preview · Article · Sep 2011 · PROCESS BIOCHEMISTRY
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    ABSTRACT: Biofuel-bioenergy production has generated intensive interest due to increased concern regarding limited petroleum-based fuel supplies and their contribution to atmospheric CO2 levels. Biofuel research is not just a matter of finding the right type of biomass and converting it to fuel, but it must also be economically sustainable on large-scale. Several aspects of cyanobacteria and microalgae such as oxygenic photosynthesis, high per-acre productivity, non-food based feedstock, growth on non-productive and non-arable land, utilization of wide variety of water sources (fresh, brackish, seawater and wastewater) and production of valuable co-products along with biofuels have combined to capture the interest of researchers and entrepreneurs. Currently, worldwide biofuels mainly in focus include biohydrogen, bioethanol, biodiesel and biogas. This review focuses on cultivation and harvesting of cyanobacteria and microalgae, possible biofuels and co-products, challenges for cyanobacterial and microalgal biofuels and the approaches of genetic engineering and modifications to increase biofuel production.
    No preview · Article · Aug 2011 · Bioresource Technology
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    ABSTRACT: The present study is focused on purification, characterization and comparison of phycoerythrins from three different marine cyanobacterial cultures--hormidium sp. A27 DM, Lyngbya sp. A09 DM and Halomicronema sp. A32 DM. 'Phycoerythrin' was successfully purified and characterized. On SDS-PAGE, the PE purified from all three young cultures showed four bands--corresponding to α and β subunits of each of PE-I and PE-II. However, phycoerythrin purified after prolonged growth of Phormidium sp. A27 DM and Halomicronema sp. A32DM showed only one band corresponding to 14 kDa whereas Lyngbya sp. A09 DM continued to produce uncleaved phycoerythrin. The absorption spectra of purified PEs from all the three young and old cultures showed variations however the fluorescence studies of the purified PEs in all cases gave the emission spectra at around 580 nm. The described work is of great importance to understand the role of phycoerythrin in adapting cyanobacteria to stress conditions.
    No preview · Article · Sep 2010 · Bioresource Technology
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    ABSTRACT: a b s t r a c t The rod-like phycobilisome (PBS) in cyanobacterium is the light-harvesting complex of phycoerythrin (PE), phycocyanin (PC) and allophycocyanin (APC). The orderly degradation of PBS was observed under starvation conditions. A 14 kDa truncated fragment of a-subunit of PE (F-aPE) was identified from the degraded product. F-aPE was purified to homogeneity, sequenced and crystallized. The merohedrally twinned crystals with a twinning factor of approximately 0.5 were obtained. The crystal structure of F-aPE was determined with molecular replacement method using detwinned data and refined to an R cryst factor of 23.2% (R free = 27.6%). The structure consisted of two crystallographically independent molecules in the asymmetric unit. The two molecules were designated as molecules A and B with a buried area of 200 Å 2 at the interface. The structure of F-aPE consists of seven a-helices A, B, E, F, F 0 , G and H. The first 31 N-terminal residues that fold into parallel a-helices X and Y in other PEs are not present in the amino acid sequence of F-aPE. Both molecules, A and B contain two chromophore ligands, PEB1 and PEB2 in each. These are covalently linked to the polypeptide chain through Cys82 and Cys139, respectively. The superimposition of C a tracings of molecules A and B shows an r.m.s. shift of 1.0 Å A 0 indicating that the structures of two independent molecules are very similar. The degradation of phycobilisome proteins under starvation stress seems to occur to supplement the requirement of amino acids for protein synthe-sis and to reduce the absorption of light energy.
    Full-text · Article · Apr 2010 · Journal of Structural Biology
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    Asha Parmar · Niraj Kumar Singh · Datta Madamwar
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    ABSTRACT: Allophycocyanin (APC) is the least-studied cyanobacterial bile-pigment invariably present within the phycobilisome core of cyanobacteria. In the present study, we describe a simple, cost-effective, and reproducible method for the purification of APC from a local isolate, Geitlerinema sp. A28DM. The pigment was extracted from the algal biomass and precipitated with 0.25% aqueous solution of the highly aromatic cationic dye “ethodin.” The precipitated APC was then subjected to a single size-exclusion chromatographic step using Sephadex G-100. Pure cyanobacterial APC (C-APC) (A652/A280 of 3.2) was obtained and characterized by its absorption spectrum with maximum at 652 nm and a shoulder at 620 nm, and by SDS-PAGE, showing two bands with molecular masses of 15 and 17.5 kDa, corresponding to α and β subunits of the biliprotein. The final yield of C-APC was 66% from its content in the crude extract. The procedure appears to be promising for wider applications and larger production of APC.
    Full-text · Article · Feb 2010 · Journal of Phycology
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    Niraj Kumar Singh · Asha Parmar · Datta Madamwar
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    ABSTRACT: Phycocyanin is a major protein produced by cyanobacteria, but very few phycocyanin-producing strains have been reported. In the present study, response surface methodology (RSM) involving a central composite design for four factors was successfully employed to optimize medium components for increased production of phycocyanin from Phormidium ceylanicum. The production of phycocyanin and interactions between sodium nitrate, calcium chloride, trace metal mix and citric acid stock were investigated and modeled. Under optimized condition P. ceylanicum was able to give 2.3-fold increase in phycocyanin production in comparison to commonly used BG 11 medium in 32 days. We have demonstrated the extraction, purification and characterization of C-phycocyanin using novel method based on filtration and single step chromatography. The protein was extracted by repeated freeze-thaw cycles and the crude extract was filtered and concentrated in stirred ultrafiltration cell (UFC). The UFC concentrate was then subjected to a single ion exchange chromatographic step. A purity ratio of 4.15 was achieved from a starting value of 1.05. The recovery efficiency of C-phycocyanin from crude extract was 63.50%. The purity was checked by electrophoresis and UV-Vis spectroscopy.
    Full-text · Article · Mar 2009 · Bioresource Technology

Publication Stats

265 Citations
31.82 Total Impact Points


  • 2009-2014
    • Sardar Patel University
      Vallabh Vidhyanagar, Gujarāt, India
  • 2012
    • Tata Institute of Fundamental Research
      • Department of Chemical Sciences
      Mumbai, Maharashtra, India