The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform
P. R. Adiga - One of the best experts on this subject based on the ideXlab platform.
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Isolation and characterization of riboflavin carrier Protein from human amniotic fluid.
Biochemistry international, 1992Co-Authors: Puttur D Prasad, Pooja Malhotra, Anjali A. Karande, P. R. AdigaAbstract:A specific Protein exhibiting immunological cross-reactivity with chicken riboflavin carrier Protein has been purified to homogeneity from human amniotic fluid by use of ion-exchange and affinity chromatography. The Protein is similar to its Avian counterpart in terms of molecular size, distribution of 125I-labelled tryptic peptides during finger printing, and preferential binding to riboflavin. Immunologically, they are homologous since most of the monoclonal antibodies raised against the Avian Protein cross-react with the purified human vitamin carrier.
Enrico Rizzarelli - One of the best experts on this subject based on the ideXlab platform.
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Prion Proteins leading to neurodegeneration.
Current Alzheimer research, 2008Co-Authors: Diego La Mendola, Adriana Pietropaolo, Claudio Zannoni, Giuseppe Pappalardo, Enrico RizzarelliAbstract:Prion diseases are fatal neurodegenerative disorders related to the conformational alteration of the prion Protein (PrP C) into a pathogenic and protease-resistant isoform PrP(Sc). PrP(C) is a cell surface glycoProtein expressed mainly in the central nervous system and despite numerous efforts to elucidate its physiological role, the exact biological function remains unknown. Many lines of evidences indicate that prion is a copper binding Protein and thus involved in the copper metabolism. Prion Protein is not expressed only in mammals but also in other species such as birds, reptiles and fishes. However, it is noteworthy to point out that prion diseases are only observed in mammals while they seem to be spared to other species. The chicken prion Protein (chPrP C) shares about 30% of identity in its primary sequence with mammal PrP C. Both types of Proteins have an N-terminal domain endowed with tandem amino acid repeats (PHNPGY in the Avian Protein, PHGGGWQ in mammals), followed by a highly conserved hydrophobic core. Furthermore, NMR studies have highlighted a similar globular domain containing three alpha-helices, one short 3(10)-helix and a short antiparallel beta-sheet. Despite this structural similarity, it should be noted that the normal isoform of mammalian PrP C is totally degraded by Proteinase K, while Avian PrP C is not, thereby producing N-terminal domain peptide fragments stable to further proteolysis. Notably, the hexarepeat domain is considered essential for Protein endocytosis, and it is supposed to be the analogous copper-binding octarepeat region of mammalian prion Proteins. The number of copper binding sites, the affinity and the coordination environment of metal ions are still matter of discussion for both mammal and Avian Proteins. In this review, we summarize the similarities and the differences between mammalian and Avian prion Proteins, as revealed by studies carried out on the entire Protein and related peptide fragments, using a range of experimental and computational approaches. In addition, we report the metal-driven conformational alteration, copper binding modes and the superoxide dismutase-like (SOD-like) activity of the related copper(II) complexes.
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Unveiling the role of histidine and tyrosine residues on the conformation of the Avian prion hexarepeat domain.
The journal of physical chemistry. B, 2008Co-Authors: Adriana Pietropaolo, Luca Muccioli, Claudio Zannoni, Diego La Mendola, Giuseppe Maccarrone, Giuseppe Pappalardo, Enrico RizzarelliAbstract:The prion Protein (PrPC) is a glycoProtein that in mammals, differently from Avians, can lead to prion diseases, by misfolding into a β-sheet-rich pathogenic isoform (PrPSc). Mammal and Avian Proteins show different N-terminal tandem repeats: PHGGGWGQ and PHNPGY, both containing histidine, whereas tyrosine is included only in the primary sequence of the Avian Protein. Here, by means of potentiometric, circular dichroism (CD), and molecular dynamics (MD) studies at different pH values, we have investigated the conformation of the Avian tetrahexarepeat (PHNPGY)4 (TetraHexaPY) with both N- and C-termini blocked by acetylation and amidation, respectively. We have found, also with the help of a recently proposed Protein chirality indicator (Pietropaolo, A.; Muccioli, L.; Berardi, R.; Zannoni, C. Proteins 2008, 70, 667−677), a conformational dependence on the protonation states of histidine and tyrosine residues: the turn formation is pH driven, and at physiological pH a pivotal role is played by the tyrosine...
Beat Trueb - One of the best experts on this subject based on the ideXlab platform.
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An α-Actinin Binding Site of Zyxin Is Essential for Subcellular Zyxin Localization and α-Actinin Recruitment
The Journal of biological chemistry, 1999Co-Authors: Matthias Reinhard, Jürg Zumbrunn, Daniel Jaquemar, Monika Kuhn, Ulrich Walter, Beat TruebAbstract:Abstract The LIM domain Protein zyxin is a component of adherens type junctions, stress fibers, and highly dynamic membrane areas and appears to be involved in microfilament organization. Chicken zyxin and its human counterpart display less than 60% sequence identity, raising concern about their functional identity. Here, we demonstrate that human zyxin, like the Avian Protein, specifically interacts with α-actinin. Furthermore, we map the interaction site to a motif of approximately 22 amino acids, present in the N-terminal domain of human zyxin. This motif is both necessary and sufficient for α-actinin binding, whereas a downstream region, which is related in sequence, appears to be dispensable. A synthetic peptide comprising human zyxin residues 21–42 specifically binds to α-actinin in solid phase binding assays. In contrast to full-length zyxin, constructs lacking this motif do not interact with α-actinin in blot overlays and fail to recruit α-actinin in living cells. When zyxin lacking the α-actinin binding site is expressed as a fusion Protein with green fluorescent Protein, association of the recombinant Protein with stress fibers is abolished, and targeting to focal adhesions is grossly impaired. Our results suggest a crucial role for the α-actinin-zyxin interaction in subcellular zyxin localization and microfilament organization.
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Molecular cloning of Avian matrix Gla Protein.
Biochimica et biophysica acta, 1998Co-Authors: Markus Wiedemann, Beat Trueb, Daniele BelluoccioAbstract:Abstract Matrix Gla Protein plays an essential role in preventing the calcification of blood vessel walls, cartilage and other tissues. We report here the primary structure of chicken matrix Gla Protein as deduced from the cDNA sequence. The Avian Protein exhibited the characteristic motifs previously identified in the mammalian Proteins, but its amino acid sequence shared only 51–56% identity with the latter Proteins. Moreover, a region proposed to function as binding site for γ-carboxylase in the mammalian Proteins was poorly conserved in the chicken Protein. Our sequence data should be helpful in the design of mutational analyses which are intended to characterize functional interactions of matrix Gla Proteins with other Proteins.
C. L. Townes - One of the best experts on this subject based on the ideXlab platform.
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Antimicrobial peptides 267 Characterization of AWAP IV, the C-terminal domain of the Avian Protein AWAK
2016Co-Authors: C. L. Townes, P. Milona, J. HallAbstract:AWAP IV constitutes the C-terminal domain of the larger 81 kDa Protein AWAK [Avian WAP (whey acidic Protein) domain- and Kunitz domain-containing], which is predicted, through conserved domain database searching, to contain at least four WAP domains and one Kunitz domain. RT (reverse transcription)–PCR analyses revealed mRNA transcripts encoding AWAP IV in the small intestinal and kidney tissues of 5-day-old Salmonella-infected chicks. Time-kill antimicrobial assays using rAWAP IV (recombinant AWAP IV) cell lysate indicated antimicrobial activity against Gram-positive and Gram-negative bacteria including Salmonella, Streptococcus and Staphylococcus spp. In addition, permeabilization of the outer membrane of Salmon-ella, as shown by the NPN (N-phenyl-1-naphthylamine) fluorescent probe assay, supported the ability of rAWAP IV to disrupt prokaryotic membranes. WAP domains can function as inhibitors of serine protease activity, and the microbial serine proteases subtilisin and Proteinase K were inhibited by rAWAP IV cell lysate. However, at comparable concentrations, no significant inhibition of the mammalian serine protease elastase was observed. The combined broad-spectrum antibacterial and anti-protease activities of AWAP IV suggest a novel role in the Avian innate defence mechanisms operating against microbial infection
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Characterization of AWAP IV, the C-terminal domain of the Avian Protein AWAK
Biochemical Society Transactions, 2006Co-Authors: C. L. Townes, P. Milona, J. HallAbstract:AWAP IV constitutes the C-terminal domain of the larger 81 kDa Protein AWAK [Avian WAP (whey acidic Protein) domain- and Kunitz domain-containing], which is predicted, through conserved domain database searching, to contain at least four WAP domains and one Kunitz domain. RT (reverse transcription)–PCR analyses revealed mRNA transcripts encoding AWAP IV in the small intestinal and kidney tissues of 5-day-old Salmonella-infected chicks. Time-kill antimicrobial assays using rAWAP IV (recombinant AWAP IV) cell lysate indicated antimicrobial activity against Gram-positive and Gram-negative bacteria including Salmonella, Streptococcus and Staphylococcus spp. In addition, permeabilization of the outer membrane of Salmonella, as shown by the NPN (N-phenyl-1-naphthylamine) fluorescent probe assay, supported the ability of rAWAP IV to disrupt prokaryotic membranes. WAP domains can function as inhibitors of serine protease activity, and the microbial serine proteases subtilisin and Proteinase K were inhibited by rAWAP IV cell lysate. However, at comparable concentrations, no significant inhibition of the mammalian serine protease elastase was observed. The combined broad-spectrum antibacterial and anti-protease activities of AWAP IV suggest a novel role in the Avian innate defence mechanisms operating against microbial infection.
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The novel Avian Protein, AWAK, contains multiple domains with homology to protease inhibitory modules
Molecular immunology, 2005Co-Authors: Christopher J. Nile, C. L. Townes, Barry H. Hirst, Judith HallAbstract:We report the purification of a 3.5 kDa peptide with antimicrobial activity from the mucosa and epithelial cells of chicken intestine. The peptide contains a pattern of cysteines characteristic of a whey acidic Protein (WAP) domain and was identified as the carboxy terminal fragment of a novel 767 amino acid Avian Protein which has a proposed molecular weight of 81 kDa. Using the conserved domain database (CDD) we identified this 81 kDa Protein to contain multiple amino acid motifs with homology to WAP domains and an amino acid motif with homology to a Kunitz Proteinase inhibitor domain. We propose to call this Avian Protein AWAK (Avian WAP motif containing, Kunitz domain containing). The presence of WAP and Kunitz modules suggests that AWAK has Proteinase inhibitor activity. RT-PCR analyses demonstrated expression of the AWAK gene in the chicken intestine.
Jean-pierre Jost - One of the best experts on this subject based on the ideXlab platform.
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5-Methylcytosine DNA glycosylase activity is also present in the human MBD4 (G/T mismatch glycosylase) and in a related Avian sequence
Nucleic Acids Research, 2000Co-Authors: Yong Zheng, Steffen Schwarz, Stéphane Thiry, Michel Siegmann, Herbert Angliker, Jean-pierre JostAbstract:A 1468 bp cDNA coding for the chicken homolog of the human MBD4 G/T mismatch DNA glycosylase was isolated and sequenced. The derived amino acid sequence (416 amino acids) shows 46% identity with the human MBD4 and the conserved catalytic region at the C-terminal end (170 amino acids) has 90% identity. The non-conserved region of the Avian Protein has no consensus sequence for the methylated DNA binding domain. The recombinant Proteins from human and chicken have G/T mismatch as well as 5-methylcytosine (5-MeC) DNA glycosylase activities. When tested by gel shift assays, human recombinant Protein with or without the methylated DNA binding domain binds equally well to symmetrically, hemimethylated DNA and non-methylated DNA. However, the enzyme has only 5-MeC DNA glycosylase activity with the hemimethylated DNA. Footprinting of human MBD4 and of an N-terminal deletion mutant with partially depurinated and depyrimidinated substrate reveal a selective binding of the Proteins to the modified substrate around the CpG. As for 5-MeC DNA glycosylase purified from chicken embryos, MBD4 does not use oligonucleotides containing mCpA, mCpT or mCpC as substrates. An mCpG within an A+T-rich oligonucleotide is a much better substrate than an A+T-poor sequence. The Km of human MBD4 for hemimethylated DNA is ∼10 –7 Mw ith aV max of ∼10 –11 mol/h/µg Protein. Deletion mutations show that G/T mismatch and 5-MeC DNA glycosylase are located in the C-terminal conserved region. In sharp contrast to the 5-MeC DNA glycosylase isolated from the chicken embryo DNA demethylation complex ,t he two enzymatic activities of MBD4 are strongly inhibited by RNA. In situ hybridization with antisense RNA indicate that MBD4 is only located in dividing cells of differentiating embryonic tissues.
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5-Methylcytosine DNA glycosylase activity is also present in the human MBD4 (G/T mismatch glycosylase) and in a related Avian sequence
Nucleic Acids Research, 2000Co-Authors: Yong Zheng, Steffen Schwarz, Stéphane Thiry, Michel Siegmann, Herbert Angliker, Jean-pierre JostAbstract:: A 1468 bp cDNA coding for the chicken homolog of the human MBD4 G/T mismatch DNA glycosylase was isolated and sequenced. The derived amino acid sequence (416 amino acids) shows 46% identity with the human MBD4 and the conserved catalytic region at the C-terminal end (170 amino acids) has 90% identity. The non-conserved region of the Avian Protein has no consensus sequence for the methylated DNA binding domain. The recombinant Proteins from human and chicken have G/T mismatch as well as 5-methylcytosine (5-MeC) DNA glycosylase activities. When tested by gel shift assays, human recombinant Protein with or without the methylated DNA binding domain binds equally well to symmetrically, hemimethylated DNA and non-methylated DNA. However, the enzyme has only 5-MeC DNA glycosylase activity with the hemimethylated DNA. Footprinting of human MBD4 and of an N-terminal deletion mutant with partially depurinated and depyrimidinated substrate reveal a selective binding of the Proteins to the modified substrate around the CpG. As for 5-MeC DNA glycosylase purified from chicken embryos, MBD4 does not use oligonucleotides containing mCpA, mCpT or mCpC as substrates. An mCpG within an A+T-rich oligonucleotide is a much better substrate than an A+T-poor sequence. The K:(m) of human MBD4 for hemimethylated DNA is approximately 10(-7) M with a V:(max) of approximately 10(-11) mol/h/microgram Protein. Deletion mutations show that G/T mismatch and 5-MeC DNA glycosylase are located in the C-terminal conserved region. In sharp contrast to the 5-MeC DNA glycosylase isolated from the chicken embryo DNA demethylation complex, the two enzymatic activities of MBD4 are strongly inhibited by RNA. In situ hybridization with antisense RNA indicate that MBD4 is only located in dividing cells of differentiating embryonic tissues.
