Disulphide Bridges (disulphide + bridge)

Distribution by Scientific Domains


Selected Abstracts


Six novel mutations including triple heterozygosity for Phe31Ser, 514delT and 516T,G factor X gene mutations are responsible for congenital factor X deficiency in patients of Nepali and Indian origin

JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 7 2005
G. JAYANDHARAN
Summary., Factor X (FX) deficiency is a rare (1 : 100000) autosomal recessive disorder caused by heterogeneous mutations in FX gene. We have studied the molecular basis this disease in six Indian and one Nepali patients. Diagnosis was confirmed by measuring the FX coagulant activity (FX: C) using a PT based assay. Six of them had a FX: C of < 1% and one patient had 24% coagulant activity. Mutations were identified in all the seven patients. These included eight (88.8%) missense and one frame-shift (11.2%) mutations of which six were novel. Three of the novel mutations, a Phe31Ser affecting ,Gla' domain and 514delT and 516T,G mutations affecting Cys132 in ,connecting region' were identified in a triple compound heterozygous state in a Nepali patient presenting with a severe phenotype. Two other novel mutations, Gly133Arg, may affect the disulphide bridge between Cys132-Cys302 in the connecting region while Gly223Arg may perturb the catalytic triad (His236, Asp282 and Ser379). The other novel mutation, Ser354Arg, involves the replacement of a small-buried residue by a large basic aminoacid and is likely to have steric or electrostatic effects in the pocket involving Lys351-Arg347-Lys414 that contributes to the core epitope of FXa for binding to FVa. Three previously reported mutations, Thr318Met; Gly323Ser; Gly366Ser were also identified. This is the first report of the molecular basis of FX deficiency in patients from the Indian subcontinent. [source]


Cloning and expression analysis of a cDNA encoding lipoprotein lipase from the liver of adult grass carp (Ctenopharyngodon idella)

AQUACULTURE RESEARCH, Issue 16 2009
Han-Liang Cheng
Abstract A full-length cDNA coding lipoprotein lipase (LPL) was cloned from the liver of adult grass carp (Ctenopharyngodon idella) using reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends approaches. The cDNA obtained was 2414 bp long with a 1524 bp open reading frame encoding 507 amino acids, including a putative signal peptide 21 amino acids long. The LPL protein has a calculated molecular weight of 57.77 kDa and an isolectric point of 8.132. The main domains of LPL, such as catalytic site, disulphide bridge, N-linked glycosylation site, heparin-binding domain, lipid-binding site and site of dimer formation, are basically conserved between the grass carp and other vertebrates. The tissue distribution of LPL mRNA in the liver, head kidney, mesenteric adipose tissue, heart and white muscle of adult grass carp was analysed using the semi-quantitative RT-PCR method using ,-actin gene as an internal control; the result showed that the expressions of LPL mRNA were detected in all examined tissues of adult grass carp. The expression levels of LPL in the mesenteric adipose tissue were the highest among these tissues, followed by the liver and head kidney and the lowest expression was found in the heart and white muscle. [source]


Feather keratin hydrolysis by a Vibrio sp. strain kr2

JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2000
S. Sangali
The aim of the study was to characterize feather-degrading bacteria isolated from poultry industry waste. A Vibrio sp. strain kr2 producing a high keratinolytic activity when cultured on native feather-containing broth was isolated. The bacterium grew with an optimum at pH 6·0 and 30 °C, where maximum feather-degrading activity was also observed. Keratinase production was similar at both 25 and 30 °C, while the maximum concentration of soluble protein was reached at 30 °C. Reduction of disulphide bridges was also observed, increasing with cultivation time. The keratinase of strain kr2 was active on azokeratin, azocasein, benzoyl-arginine- p -nitroanilide and Ala-Ala- p -nitroanilide as substrates. The amino acid composition of the feather hydrolysate was determined, presenting similarities with that reported for feather lysate, feather meal and raw feathers. A novel feather-degrading bacterium was isolated and characterized, showing high keratinolytic activity. Complete feather degradation was achieved during cultivation. Strain kr2 shows potential for use for biotechnological processes involving keratin hydrolysis. [source]


Antibacterial peptides: basic facts and emerging concepts

JOURNAL OF INTERNAL MEDICINE, Issue 3 2003
H. G. Boman
Abstract., Boman HG (Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden). Antibacterial peptides: basic facts and emerging concepts (Review). J Intern Med 2003; 254: 197,215. Antibacterial peptides are the effector molecules of innate immunity. Generally they contain 15,45 amino acid residues and the net charge is positive. The cecropin type of linear peptides without cysteine were found first in insects, whilst the defensin type with three disulphide bridges were found in rabbit granulocytes. Now a database stores more than 800 sequences of antibacterial peptides and proteins from the animal and plant kingdoms. Generally, each species has 15,40 peptides made from genes, which code for only one precursor. The dominating targets are bacterial membranes and the killing reaction must be faster than the growth rate of the bacteria. Some antibacterial peptides are clearly multifunctional and an attempt to predict this property from the hydrophobicity of all amino acid side chains are given. Gene structures and biosynthesis are known both in the fruit fly Drosophila and several mammals. Humans need two classes of defensins and the cathelicidin-derived linear peptide LL-37. Clinical cases show that deficiencies in these peptides give severe symptoms. Examples given are morbus Kostmann and atopic allergy. Several antibacterial peptides are being developed as drugs. [source]


Four conserved intramolecular disulphide linkages are required for secretion and cell wall localization of a hydrophobin during fungal morphogenesis

MOLECULAR MICROBIOLOGY, Issue 1 2005
Michael J. Kershaw
Summary Hydrophobins are morphogenetic proteins produced by fungi during assembly of aerial hyphae, sporulation, mushroom development and pathogenesis. Eight cysteine residues are present in hydrophobins and form intramolecular disulphide bonds. Here, we show that expressing eight cysteine,alanine substitution alleles of the MPG1 hydrophobin gene from Magnaporthe grisea causes severe defects in development of aerial hyphae and spores. Immunolocalization revealed that Mpg1 hydrophobin variants, lacking intact disulphide bonds, retain the capacity to self-assemble, but are not secreted to the cell surface. This provides the first genetic evidence that disulphide bridges in a hydrophobin are dispensable for aggregation, but essential for secretion. [source]


Structural stability and heat-induced conformational change of two complement inhibitors: C4b-binding protein and factor H

PROTEIN SCIENCE, Issue 5 2004
Lena Kask
C4BP, C4b-binding protein; FH, factor H; CCP, complement control protein; CD, circular dichroism; FTIR, Fourier transform-infrared spectroscopy; PT, prothrombin; VCP, vaccinia virus complement control protein Abstract The complement inhibitors C4b-binding protein (C4BP) and factor H (FH) both consist of complement control protein (CCP) domains. Here we examined the secondary structure of both proteins by circular dichroism and Fourier-transform infrared technique at temperatures ranging from 30°C,90°C. We found that predominantly ,-sheet structure of both proteins was stable up to 70°C, and that a reversible conformational change toward ,-helix was apparent at temperatures ranging from 70°C to 90°C. The ability of both proteins to inhibit complement was not impaired after incubation at 95°C, exposure to extreme pH conditions, and storage at room temperature for several months. Similar remarkable stability was previously observed for vaccinia virus control protein (VCP), which is also composed of CCP domains; it therefore seems to be a general property of CCP-containing proteins. A typical CCP domain has a hydrophobic core, which is wrapped in ,-sheets and stabilized by two disulphide bridges. How the CCP domains tolerate harsh conditions is unclear, but it could be due to a combination of high content of prolines, hydrophobic residues, and the presence of two disulphide bridges within each domain. These findings are of interest because CCP-containing complement inhibitors have been proposed as clinical agents to be used to control unwanted complement activation that contributes to many diseases. [source]


The recombinant major allergen of Parietaria judaica and its hypoallergenic variant: in vivo evaluation in a murine model of allergic sensitization

CLINICAL & EXPERIMENTAL ALLERGY, Issue 3 2004
A. Orlandi
Summary Background Par j 1 represents the major allergenic component of Parietaria judaica pollen. Its three-dimensional structure is stabilized by four disulphide bridges. A family of three-dimensional mutants of the recombinant Par j 1 (rPar j 1) allergen, showing reduced allergenicity and retained T cell recognition has been recently developed by site-directed mutagenesis. Objective To develop and characterize a murine model of IgE sensitization to rPar j 1. To evaluate similarities between the murine model and the human IgE response. To investigate in this model the recognition of a hypoallergenic mutant of Par j 1, and to study the immune responses elicited in mice by the mutant itself. Methods BALB/c mice were sensitized by two intraperitoneal immunizations with rPar j 1 in alum on days 0 and 21. Allergen-specific serum IgE and IgG responses were studied by direct ELISA and immunoblotting, ELISA inhibition and competitive ELISA. Cell proliferation was evaluated in splenocyte cultures. Results Sensitization with rPar j 1 induced high levels of IgE and IgG1 vs. low levels of IgG2a. Mouse antibodies specific to rPar j 1 were able to compete with human IgE for recognition of rPar j 1. IgE from mice immunized with rPar j 1 showed a significantly reduced binding activity towards the hypoallergenic variant rPjC, which lacks three disulphide bridges. On the contrary, rPjC was recognized by IgG1 and IgG2a antibodies as well as rPar j 1. The proliferative response to rPjC by splenocytes from mice immunized with rPar j 1 was comparable to that stimulated by rPar j 1. Immunization with rPjC induced low levels of IgE antibodies to the rPjC itself, while IgG and proliferative responses were similar to those induced by rPar j 1. Conclusion Conformational variants of allergens, displaying reduced allergenicity accompanied by retained IgG and T cell recognition, offer a safe, specific and flexible approach to immunotherapy of type I allergy. Our mouse model of IgE sensitization to a recombinant allergen, mimicking the human response to its native counterpart, could provide valuable information for pre-clinical testing of such hypoallergenic molecules. [source]