Protein and Peptide Letters - Volume 11, Issue 2, 2004
Volume 11, Issue 2, 2004
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Splicing of Unnatural Amino Acids Into Proteins: A Peptide Model Study
Authors: Shoufa Han and Ronald E. ViolaS-Ethyl 2-azidohexanethioate (N3-Hex-SEt), an unnatural amino acid analog of leucine, is coupled with L-cysteine ethyl ester (NH2-Cys-OEt) to obtain N3-Hex-Cys-OEt by native chemical ligation. Coupling of this dipeptide with N-t-butoxycarbonyl-2-diphenylphosphinoethanethioglycinate produces the tripeptide, t-Boc-Gly-Hex-Cys-OEt, in high yield. These reactions suggest an approach for the incorporation of unnatural amino acids into proteins by successive native chemical ligation and Staudinger ligation.
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Conformation of the Cecropin-Melittin Hybrid, Cecropin A(1-8)-Melittin (1-18) Antibacterial Peptide
Authors: Savita Tauro, Evans Coutinho and Sudha SrivastavaCecropin A (1-8)-Melittin (1-18) is a synthetic cecropin A-melittin hybrid peptide with leishmanicidal activity. The primary sequence of the peptide is as follows: KWKLPKKIGIGAVLKVLTTGLPALIS-NH2. 1H and 13C 2D NMR techniques were used to deduce the conformational parameters of chemical shift, 3JNHα coupling constants, temperature coefficients of NH chemical shifts and the pattern of intra and inter-residue nOe's. NMR studies were carried out in water (pH 6.0) and hexafluoroacetone (HFA). The peptide was found in a β-pleated structure in water, and in HFA it adopts a right-handed α-helix conformation. Solution structures generated using restrained molecular dynamics simulations were refined by Mardigras to R factors ranging from 0.5 to 0.6.
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Electrostatic and Hydrophobic Interactions Play A Major Role in the Stability and Refolding of Halophilic Proteins.
Authors: Tsutomu Arakawa and Masao TokunagaIn general, halophilic proteins are stable only in the presence of salts at high concentrations. Not only is high salt concentration important for structural stability of halophilic proteins, but also refolding of a denatured halophilic protein requires high salt concentration. This review summarizes the importance of electrostatic charge shielding and hydrophobic interactions in the stability and refolding of halophilic proteins.
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Urea-Induced Denaturation of β-Trypsin: An Evidence for a Molten Globule State
Authors: Maria H. N. Brumano and Maria Goreti de Almeida OliveiraThe denaturation of β-trypsin induced by urea was investigated by fluorescence and circular dichroism. A transient denatured state was found at 2 M urea in both intrinsic fluorescence spectrum and bis-(8-anilino-1-naphtalene sulfonate) (bis-ANS) binding. In addition, the absence of tertiary contacts and presence of secondary structure for this state, are consistent with an intermediate equilibrium state having features of molten globule.
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Differential Desensitization of Somatostatin Receptor Subtypes in AtT-20 Cells
Authors: Fredric C. Mazza and Allan D. BlakeNonpeptidyl agonists for the somatostatin (SRIF) receptor family have been developed. We have studied the desensitization effects for two of these agonists upon SRIF receptor function in AtT-20 cells, a neuroendocrine tumor cell, which endogenously expresses two distinct SRIF receptor, subtypes. We observe that SRIF and the nonpeptidyl, subtype selective agonists, differentially regulate SRIF receptor subtypes in the AtT-20 cell.
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Calcineurin Hydrolysis of Para-Nitrophenyl Phosphorothioate
Authors: Donna J. Spannaus-Martin and Bruce L. Martinpara-Nitrophenyl phosphorothioate (pNPT) was hydrolyzed by calcineurin at initial rates slightly, but comparable to rates for para-nitrophenyl phosphate (pNPP). Kinetic characterization yielded higher estimates for both Km and Vmax compared to pNPP. Metal ion activation of phosphorothioate hydrolysis was more promiscuous. Unlike the hydrolysis of with pNPP, Ca2+, Mg2+, and Ba2+ activated calcineurin as well as Mn2+.
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Comparative Study of Interaction of Two Type Ii Ribosome-Inactivating Proteins And Their A-Chains With Model Membrane
Authors: Hong Xu, Bao-Zhong Wang and Wang-Yi LiuBoth cinnamomin and ricin are type II ribosome-inactivating proteins. Cinnamomin is less cytotoxic compared with ricin. In order to clarify the mechanism of their different cytotoxicities, the interaction of cinnamomin and its A-chain with model membrane was investigated and compared with that of ricin and its A-chain. It was revealed that cinnamomin is less effective than ricin in interacting with model membrane. Cinnamomin A-chain interacts with model membrane much less violently than ricin Achain. The differences in the interaction of cinnamomin, ricin or their A-chains with model membrane might at least in part indicate the different cytotoxicity between cinnamomin and ricin.
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Overexpression, Purification and Characterization of Recombinant Salmon Calcitonin, A Therapeutic Protein, in Streptomyces Avermitilis
Authors: Chiranjib Chakraborty, Shyam Nandi and S. SinhaCalcitonin (CT) is a peptide hormone produced by the parafollicular cells of the thyroid gland in mammals and by the ultimobranchial gland of birds and fish. Salmon calcitonin (sCT), which is more potent and longer lasting than human CT, has been used widely for the treatment of osteoporosis, paget's disease, hypercalcemic shock and chronic pain in terminal cancer patients. sCT is one of the many bioactive peptides that require C-terminal amidation for full biological activity. In this study we describe the overexpression and over-production of C-terminal amidated sCT in recombinant Streptomyces avermitilis. With this approach the utilization of expensive peptide synthesis can be circumvented.
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The C-Terminus of Camkii Is Truncated When Expressed In E. Coli
Authors: M. Praseeda, Mary K. Beena, Sarah J. Asha and R. V. OmkumarThe neuronal enzyme Calcium / calmodulin dependent protein kinase type II (CaMKII) is a key molecule in biochemical events necessary for learning and memory. The α-subunit of CaMKII expressed in E. coli as well as in insect cells shows similar catalytic behavior [Praseeda, M., Pradeep, K. K., Krupa, A., Sri Krishna, S., Leena, S., Rajeev Kumar, R., John Cheriyan, Mayadevi, M., Srinivasan, N., and Omkumar, R. V. (2003) Biochem. J. In Press]. The association domain of the enzyme has been crystallized in its native multimeric form after expression in E. coli [Hoelz, A., Nairn, A. C. and Kuriyan, J. (2003) Molecular Cell 11, 1241]. However a major truncation product accompanies the full-length protein when expressed in E. coli. We show by epitope labeling and immunoblotting that the truncation occurs at the C-terminal half of the protein so that the N-terminal catalytic domain is complete in the truncated product. This supports the use of the preparation of α-CaMKII expressed in E. coli for studies on functions of the catalytic site. Our data will also be helpful in designing modified prokaryotic expression systems for CaMKII devoid of the truncation product, which are easier to use compared to the insect cell system.
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α-Amylase Inhibitors from Ficus Sp. Seeds and Their Activities Towards Coleoptera Insect Pests
α-Amylase Inhibitors were isolated from Ficus sp. (Gameleira) seeds by acetone fractionation and Sephadex G-50. Two inhibitors (α-PPAI and α-ZSAI) were tested against α-amylases from coleopteran larvae. α-PPAI was active to α-amylases of Callosobruchus maculatus (52%) and Zabrotes subfasciatus (53%). α-ZSAI was strongly active to Z. subfasciatus (100%) of and Mimosestes mimosae (98%). The α-ZSAI is a glycoprotein of ∼50kDa with an IC50 value of 0.074 μg μl-1.
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Protein Extraction and Comparison of Stain Protocols for Analysis of Two-Dimensional Electrophoresis Gels
Authors: Joana Silva, Ana S. Carvalho, Rui Vitorino, Pedro Domingues, Paula Teixeira and Paul GibbsProtein extraction and the proteome of Lactobacillus delbrueckii subsp. bulgaricus were studied using different stains. The reversible silver staining technique was shown to be more sensitive than the irreversible silver stain. Coomassie colloidal was demonstrated to be as sensitive as reversible silver stain; however, the Coomassie colloidal blue solution developed a higher background and for sample preparation was more time-consuming.
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Vatairea Macrocarpa Lectin Induces Paw Edema With Leukocyte Infiltration.
A lectin from Vatairea macrocarpa (Vmac) seeds was investigated in a model of paw edema in rats and the possible involvement of leukocytes. Vmac (200 and 400μg / paw, s.c.) induced a significant time- and dose-dependent paw edema, with leukocyte infiltration, which was drastically reduced in leukopaenic animals. These data suggest a pro-inflammatory effect for this lectin that is dependent on the presence of leukocytes.
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Crystallization and Preliminary X-Ray Crystallographic Analysis of Plasmodium Falciparum S-Adenosyl-L-Homocysteine Hydrolase
S-adenosyl-L-homocysteine hydrolase from a malaria parasite Plasmodium falciparum (PfSAHH) has been crystallized by the vapor diffusion method. The crystals belong to an orthorhombic space group P212121 with the cell dimensions of a = 76.66 Å, b = 86.31 Å, and c = 335.6 Å. There are four subunits (one tetramer) per asymmetric unit. X-ray diffraction data have been collected up to 2.8 Å resolution. Selfrotation function studies suggest that the tetrameric PfSAHH molecule has the 222 point group symmetry.
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Volumes & issues
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Volume 32 (2025)
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Volume 31 (2024)
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Volume 30 (2023)
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Volume 29 (2022)
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Volume 28 (2021)
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Volume 27 (2020)
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Volume 26 (2019)
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Volume 25 (2018)
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Volume 24 (2017)
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Volume 23 (2016)
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Volume 22 (2015)
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Volume 21 (2014)
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Volume 20 (2013)
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Volume 19 (2012)
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Volume 18 (2011)
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Volume 17 (2010)
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Volume 16 (2009)
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Volume 15 (2008)
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Volume 14 (2007)
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Volume 13 (2006)
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Volume 12 (2005)
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Volume 11 (2004)
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Volume 10 (2003)
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Volume 9 (2002)
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Volume 8 (2001)
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