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111.
Raman B Guarnaccia C Nadassy K Zakhariev S Pintar A Zanuttin F Frigyes D Acatrinei C Vindigni A Pongor G Pongor S 《Nucleic acids research》2001,29(16):3377-3384
We studied the interaction between a synthetic peptide (sequence Ac-GXGGFGGXGGFXGGXGG-NH2, where X = arginine, Nω,Nω-dimethylarginine, DMA, or lysine) corresponding to residues 676–692 of human nucleolin and several DNA and RNA substrates using double filter binding, melting curve analysis and circular dichroism spectroscopy. We found that despite the reduced capability of DMA in forming hydrogen bonds, Nω,Nω-dimethylation does not affect the strength of the binding to nucleic acids nor does it have any effect on stabilization of a double-stranded DNA substrate. However, circular dichroism studies show that unmethylated peptide can perturb the helical structure, especially in RNA, to a much larger extent than the DMA peptide. 相似文献
112.
Dehairs F. Rao R. G. Chandra Mohan P. Raman A.V. Marguillier S. Hellings L. 《Hydrobiologia》2000,431(2-3):225-241
Stable carbon isotopic composition and C/N ratio were used to trace the input of carbon associated with mangrove litter into the estuary of the Godavari–Gautami delta system and Kakinada bay (Andhra Pradesh, India). Suspended organic matter in the mangrove channels was more depleted in 13C (average 13C = –24.5) than in Kakinada bay which showed 13C values for suspended matter (average 13C = –22.7) closer to those expected for marine phytoplankton. Suspended organic matter from mangrove channels was enriched in nitrogen (average C/N atom ratio 12.7) and 13C (average 13C = –24.5) relative to mangrove leaf litter, which had a C/N ratio of 75 and a 13C value of –28. Lowest C/N ratios for suspended matter were observed during southwest monsoon when rainfall was highest. Although in general, mangrove litter fall was also lower during this period, no clear correlation was observed between litter fall and C/N ratio of suspended matter. In general, the composition of suspended matter pointed towards phytoplankton as a major component. Isotopic composition of zooplankton suggested selective feeding on 13C-enriched, marine phytoplankton in open Kakinada bay and on 13C-depleted organic matter, such as estuarine phytoplankton and mangrove litter, in the mangrove channels. From the 13C signature, it appeared that mangrove carbon was present to some extent in zooplankton and macrofauna from the mangrove mudflats and channels, but the signal rapidly decreased in Kakinada bay. Nitrogen isotopic composition of zooplankton and macrofauna indicated a progressive enrichment of 15N away from the mangrove forest towards the northern part of Kakinada bay, in approach of Kakinada city. This is thought to reflect input of anthropogenic nitrogen enriched in 15N and subsequent uptake of this enriched nitrogen into the aquatic food chain. 相似文献
113.
Indirect enzyme linked immunosorbent assays (ELISA) were developed using polyclonal antibodies against soluble cytoplasmic (SCA) and insoluble cell wall antigens (ICWA) for monitoring modulation of mycelial antigens during growth cycle of T. indica. With SCA, continuous decrease in ELISA reactivity was observed in maturing fungus cultures, suggesting that SCA were expressed predominantly during early vegetative phase and their decreasing role was apparent as the fungus matures possibly towards sporogenous mycelium. In case of ICWA, the reaction profile showed an increase up to exponential phase of growth probably due to increase in the cell division and branching of mycelium. But later, ICWA antibody reactivity was decreased which may be due to conversion of mycelial phase to sporogenous phase, a quiescent stage of growth. Characterization of changes in antigenic configuration during developmental cycle of Tilletia indica by these antibodies could prove to be useful in identification of developmentally related and virulence marker(s). 相似文献
114.
115.
HOXA5 regulates expression of the progesterone receptor 总被引:6,自引:0,他引:6
116.
The fungitoxic effects of different plant extracts on Fusarium udum, which causes wilt disease of Cajanus cajan in vitro and in vivo, were examined. The complete arrest of the radial growth of the pathogen occurred at a 10% concentration of leaf extract from Adenocallyma alliaceum. A leaf extract of Citrus medica, a root extract of Asparagus adscendens, rhizome extracts of Curcuma longa and Zingiber officinale, and a bulb extract of Allium sativum inhibited up to 100% growth at higher concentrations. A. alliaceum controlled the disease up to 100% by amending its 4% powder in unsterilized soil and 2% in sterilized soil. The population of F. udum was found to be markedly reduced following treatments with plant powders. 相似文献
117.
Ch. Mohan Rao B. Raman T. Ramakrishna K. Rajaraman D. Ghosh S. Datta V. D. Trivedi M. B. Sukhaswami 《International journal of biological macromolecules》1998,22(3-4)
α-Crystallin is a multimeric lenticular protein that has recently been shown to be expressed in several non-lenticular tissues as well. It is shown to prevent aggregation of non-native proteins as a molecular chaperone. By using a non-thermal aggregation model, we could show that this process is temperature-dependent. We investigated the chaperone-like activity of α-crystallin towards photo-induced aggregation of γ-crystallin, aggregation of insulin and on the refolding induced aggregation of β- and γ-crystallins. We observed that α-crystallin could prevent photo-aggregation of γ-crystallin and this chaperone-like activity of α-crystallin is enhanced several fold at temperatures above 30°C. This enhancement parallels the exposure of its hydrophobic surfaces as a function of temperature, probed using hydrophobic fluorescent probes such as pyrene and 8-anilinonaphthalene-1-sulfonate. We, therefore, concluded that α-crystallin prevents the aggregation of other proteins by providing appropriately placed hydrophobic surfaces; a structural transition above 30°C involving enhanced or re-organized hydrophobic surfaces of α-crystallin is important for its chaperone-like activity. We also addressed the issue of conformational aspects of target proteins and found that their aggregation prone molten globule states bind to α-crystallin. We trace these developments and discuss some new lines that suggest the role of tertiary structural aspects in the chaperone process. 相似文献
118.
119.
d-Hydantoinase from the lentil, Lens esculenta, seed is quite unstable, and has been immobilized on Diethyl amino ethyl (DEAE) cellulose by an adsorption and cross-linking
method. The immboilized d-hydantoinase exhibited 80% enzyme activity and contained 86% protein. The immobilization of the enzyme preparation does not
change its optimum pH, temperature or affinity constant, but increases its shelf-life, thermostability and stability in various
organic solvents. This immobilized d-hydantoinase can be used effectively for the production of d-amino acids from the corresponding hydantoins and may therefore be of use in the chemical and pharmaceutical industries.
Received: 28 April 1998 / Received last revision: 10 July 1998 / Accepted: 10 July 1998 相似文献
120.
Sunita Panda Ananya Nanda Nilanjan Sahu Deepak K. Ojha Biswaranjan Pradhan Anjali Rai Amol
R. Suryawanshi Nilesh Banavali Sasmita Nayak 《Bioscience reports》2022,42(3)
Inteins are auto-processing domains that implement a multistep biochemical reaction termed protein splicing, marked by cleavage and formation of peptide bonds. They excise from a precursor protein, generating a functional protein via covalent bonding of flanking exteins. We report the kinetic study of splicing and cleavage reaction in [Fe–S] cluster assembly protein SufB from Mycobacterium tuberculosis (Mtu). Although it follows a canonical intein splicing pathway, distinct features are added by extein residues present in the active site. Sequence analysis identified two conserved histidines in the N-extein region; His-5 and His-38. Kinetic analyses of His-5Ala and His-38Ala SufB mutants exhibited significant reductions in splicing and cleavage rates relative to the SufB wildtype (WT) precursor protein. Structural analysis and molecular dynamics (MD) simulations suggested that Mtu SufB displays a unique mechanism where two remote histidines work concurrently to facilitate N-terminal cleavage reaction. His-38 is stabilized by the solvent-exposed His-5, and can impact N–S acyl shift by direct interaction with the catalytic Cys1. Development of inteins as biotechnological tools or as pathogen-specific novel antimicrobial targets requires a more complete understanding of such unexpected roles of conserved extein residues in protein splicing. 相似文献