Classical complement pathway is an important innate immune mechanism, which is usually triggered ... more Classical complement pathway is an important innate immune mechanism, which is usually triggered by binding of C1q to immunoglobulins, pentraxins and other target molecules. Although the activation of the classical pathway is crucial in the host defence, its undesirable and uncontrolled activation can lead to tissue damage. Thus, understanding the molecular basis of complement activation and its inhibition are of great biomedical importance. Recently, we proposed a mechanism for target recognition and classical pathway activation by C1q, which is likely governed by calcium-controlled reorientation of macromolecular electric moment vectors. Here we sought to define the mechanism of C1q inhibition by low molecular weight disulphate compounds that bind to the globular (gC1q) domain, using experimental, computational docking and theoretical modelling approaches. Our experimental results demonstrate that betulin disulphate (B2S) and 9,9-bis(4'-hydroxyphenyl)fluorene disulphate (F2S) inhibit the interaction of C1q and its recombinant globular modules with target molecules IgG1, C-reactive protein (CRP) and long pentraxin 3 (PTX3). In most C1q-inhibitor docked complexes, there is a reduction of electric moment scalar values and similarly altered direction of electric/dipole moment vectors. This could explain the inhibitory effect by impaired electrostatic steering, lacking optimal target recognition and formation of functional complex. In the presence of the inhibitor, the tilt of gC1q domains is likely to be blocked by the altered direction of the electric moment vector. Thus, the transition from the inactive (closed) towards the active (open) conformation of C1q (i.e. the complement activation signal transmission) will be impaired and the cascade initiation disrupted. These results could serve as a starting point for the exploration of a new form of 'electric moment inhibitors/ effectors'.
Classical complement pathway is an important innate immune mechanism, which is usually triggered ... more Classical complement pathway is an important innate immune mechanism, which is usually triggered by binding of C1q to immunoglobulins, pentraxins and other target molecules. Although the activation of the classical pathway is crucial in the host defence, its undesirable and uncontrolled activation can lead to tissue damage. Thus, understanding the molecular basis of complement activation and its inhibition are of great biomedical importance. Recently, we proposed a mechanism for target recognition and classical pathway activation by C1q, which is likely governed by calcium-controlled reorientation of macromolecular electric moment vectors. Here we sought to define the mechanism of C1q inhibition by low molecular weight disulphate compounds that bind to the globular (gC1q) domain, using experimental, computational docking and theoretical modelling approaches. Our experimental results demonstrate that betulin disulphate (B2S) and 9,9-bis(4'-hydroxyphenyl)fluorene disulphate (F2S) inhibit the interaction of C1q and its recombinant globular modules with target molecules IgG1, C-reactive protein (CRP) and long pentraxin 3 (PTX3). In most C1q-inhibitor docked complexes, there is a reduction of electric moment scalar values and similarly altered direction of electric/dipole moment vectors. This could explain the inhibitory effect by impaired electrostatic steering, lacking optimal target recognition and formation of functional complex. In the presence of the inhibitor, the tilt of gC1q domains is likely to be blocked by the altered direction of the electric moment vector. Thus, the transition from the inactive (closed) towards the active (open) conformation of C1q (i.e. the complement activation signal transmission) will be impaired and the cascade initiation disrupted. These results could serve as a starting point for the exploration of a new form of 'electric moment inhibitors/ effectors'.
C1q is the target recognition protein of the classical complement pathway and a major connecting ... more C1q is the target recognition protein of the classical complement pathway and a major connecting link between innate and acquired immunity. As a charge pattern recognition molecule of innate immunity, C1q can engage a broad range of self and non-self ligands via its heterotrimeric globular (gC1q) domain and thus trigger the classical pathway. The trimeric gC1q signature domain has been identified in a variety of non-complement proteins that can be grouped together as a C1q family. The X-ray crystal structures of the gC1q domain of a few members of the C1q family reveal a compact jelly-roll b-sandwich fold similar to that of the multifunctional tumor necrosis factor (TNF) ligand family, hence the C1q and TNF superfamily. This review is an update on the structural and functional aspects of the gC1q domain of human C1q. We also mention the diverse range of proteins that utilize a gC1q domain in order to reflect on its importance as a versatile scaffold to support a variety of functions.
Objective: In the present work the concentration of abnormal immune complexes, cryoglobulins (Cgs... more Objective: In the present work the concentration of abnormal immune complexes, cryoglobulins (Cgs), in the blood of schizophrenic patients was determined, and immunochemical composition of these complexes was studied.
... exploited such that they can be used for numerous applications ranging from sensors and actua... more ... exploited such that they can be used for numerous applications ranging from sensors and actuators ... and materials that offer benefits to both constituencies [2]. The discovery of carbonnanotubes (CNTs) has ... in detail in a separate section latter) such as small size and mass, high ...
Human complement regulatory (also called inhibitory) proteins control misdirected attack of compl... more Human complement regulatory (also called inhibitory) proteins control misdirected attack of complement against autologous cells. Trypanosome and schistosome parasites which survive in the host vascular system also possess regulators of human complement. We have shown Sh-TOR, a protein with three predicted transmembrane domains, located on the Schistosoma parasite surface, to be a novel complement regulatory receptor. The N-terminal extracellular domain, Sh-TOR-ed1, binds the complement protein C2 from human serum and specifically interacts with the C2a fragment. As a result Sh-TOR-ed1 pre-incubated with C2 inhibits classical pathway (CP)mediated haemolysis of sheep erythrocytes in a dose-dependent manner. In CP-mediated complement activation, C2 normally binds to C4b to form the CP C3 convertase and Sh-TOR-ed1 has short regions of sequence identity with a segment of human C4b. We propose the more appropriate name for TOR of CRIT (complement C2 receptor inhibitory trispanning).
Pregnancy-associated plasma protein-A (PAPP-A), like alpha 2-macroglobulin (alpha 2M), is a large... more Pregnancy-associated plasma protein-A (PAPP-A), like alpha 2-macroglobulin (alpha 2M), is a large protein with homotetrameric molecular conformation. Each monomer has Mr 205 kDa. Total carbohydrate content of PAPP-A (19.4%) exceeded that of alpha 2M (8.6%). In addition to glucose (9.4%), fucose (3.1%), mannose (2.3%) and galactose (0.8%), PAPP-A contained glucuronic acid (3.8%). The amino acid composition of PAPP-A differed most significantly from alpha 2M, in the content of glutamate, glycine and lysine. Although the peptide core of both proteins were of similar size, the difference in size, of native molecules was due to the carbohydrate moiety. Whereas alpha 2M monomer was autolytically cleaved into two smaller non-identical subunits (Mr 128 and 65 kDa), no such breakdown products were observed with PAPP-A. Unlike alpha 2M, PAPP-A is not a broad spectrum protease inhibitor. Both proteins inhibited human granulocyte elastase (HGE) in a dose dependent relationship, with PAPP-A (Ki 0.2 x 10(-6) M) being a more potent inhibitor than alpha 2M (Ki 1.02 x 10(-6) M). Since PAPP-A lacked internal thiolester groups, the mechanism of HGE inhibition was unlikely to be entrapment, as defined for alpha 2M. Inhibition kinetics of HGE for PAPP-A (noncompetitive inhibitor) and alpha 2M (uncompetitive inhibitor) were distinct. Thus, these findings do not support the tenet of a common ancestral protein for PAPP-A and alpha 2M.
... THE COMPLEMENT GENES R. Duncan Campbell, SK Alex Law, Kenneth BM Reid, and Robert B. Sim Medi... more ... THE COMPLEMENT GENES R. Duncan Campbell, SK Alex Law, Kenneth BM Reid, and Robert B. Sim Medical Research Council Immunochemistry Unit, Department of Bioн chemistry, University of Oxford, South Parks Road, Oxford OXI 3QU, United Kingdom INTRODUCTION ...
Deposition of amyloid in pancreatic islets is a common feature in human type 2 diabetic subjects ... more Deposition of amyloid in pancreatic islets is a common feature in human type 2 diabetic subjects but because of its insolubility and low tissue concentrations, the structure of its monomer has not been determined. We describe a peptide, of calculated molecular mass 3905 Da, that was a major protein component of amyloid-rich pancreatic extracts of three type 2 diabetic patients. After collagenase treatment, an extract containing 20-50% amyloid was solubilized by sonication into 70% formic acid and the peptide was purified by gel filtration followed by reverse-phase high-performance liquid chromatography. We term this peptide diabetes-associated peptide, as it was not detected in extracts of pancreas from any of six normal subjects. Diabetes-associated peptide contains 37 amino acids and is 46% identical to the sequences of rat and human calcitonin gene-related peptide, indicating that these peptides are related in evolution. Sequence identities with conserved residues of the insulin A chain were also seen in a 16-residue segment. On extraction, the islet amyloid is particulate and insoluble like the core particles of Alzheimer disease. Their monomers have similar molecular masses, each having a hydropathic region that can probably form β -pleated sheets. The accumulation of amyloid, including diabetes-associated peptide, in islets may impair islet function in type 2 diabetes mellitus.
In this study, we used human tonsils for the isolation of the 60 kD component of the Ro/SSA autoa... more In this study, we used human tonsils for the isolation of the 60 kD component of the Ro/SSA autoantigen, following the method described by Wu et al. (J Immunol Methods 1989; 121:219-24).
The IL-1 receptor antagonist (IL-1RN) is a protein that binds to IL-1 receptors and inhibits the ... more The IL-1 receptor antagonist (IL-1RN) is a protein that binds to IL-1 receptors and inhibits the binding of IL-1 alpha and IL-1 beta. As a consequence, the biological activity of these two cytokines is neutralized in physiological and pathophysiological immune and inflammatory responses. In this study, using a panel of somatic rodent-human cell hybrids, we show that the gene for the human interleukin-1 receptor antagonist (IL1RN) maps to the long arm of chromosome 2. Previously, we described a length variation polymorphism within the second intron of the IL-1RN gene (Steinkasserer et al., 1991, Nucleic Acids Res. 19: 5095). Segregation of this, together with an IL-1 alpha polymorphism, was followed in a panel of five CEPH families. Linkage analysis permitted the mapping of the IL-1RN gene to band q14-q21 in the region for the IL-1 alpha and IL-1 beta loci. This study supports the view that an early gene duplication event resulted in the creation of an interleukin-1 gene family.
Complement C3 is a central component of the humoral immune system. Upon triggering of the complem... more Complement C3 is a central component of the humoral immune system. Upon triggering of the complement cascade, proteolytic fragments of C3 mediate important processes such as opsonization and lymphocyte activation. C3 possesses an internal thioester that mediates covalent attachment of proteolytically activated C3 to target surfaces. Treatment of native C3 with methylamine cleaves the thioester bond and exposes a free sulfhydryl group at the targetbinding face of the protein. Through the use of sulfhydryl-reactive heterobifunctional crosslinking and biotinylation reagents, we demonstrate the capacity to form stable, multimeric whole human C3-protein conjugates in a fashion reflecting the orientation of physiologicallyactivated C3. We speculate that this C3 conjugation strategy presents a route for targeting dendritic cells and macrophages. In addition, manipulation of the thioester bond could enhance the study of biological roles of C3 and related proteins such as C4, and also of transmissible agents that exploit complement function such as prions.
... Marilyn S. Rugg(Author), Caroline M. Milner(Author), Jens Madsen(Author), Uffe Holmskov(Autho... more ... Marilyn S. Rugg(Author), Caroline M. Milner(Author), Jens Madsen(Author), Uffe Holmskov(Author), R. Duncan Campbell(Author), Caroline M. Milner(Author), Begoña Aguado(Author), SK Alex Law(Author), A. Neil Barclay(Author), Michael C. Carroll(Author), Lisa A. Steiner ...
European journal of biochemistry / FEBS, Jan 15, 1986
Solution scattering experiments using both X-rays and neutrons are reported for human complement ... more Solution scattering experiments using both X-rays and neutrons are reported for human complement component C3 and up to six other glycoprotein fragments that are derived from C3. The X-ray and neutron molecular masses and neutron matchpoints are in agreement with the known primary sequence of C3. The X-ray radius of gyration RG of C3 is 5.2 nm and is similar for the related forms C3u, C3(a + b) and C3b. The X-ray cross-sectional radius of gyration RXS of C3b is however less than that of C3, C3u and C3(a + b). The major fragments of C3b, namely C3c and C3dg, were studied. The RG of C3c is 4.7 nm and for C3dg is 2.9 nm. C3c and C3dg do not interact when they coexist in solution in equimolar amounts. When C3u is cleaved into iC3u, the RG of iC3u increases to 5.9 nm and its RXS decreases, showing that C3c and C3dg behave as independent entities within the parent glycoprotein. Analyses of the neutron RG and RXS values by contrast variation techniques confirm the X-ray analyses, and show ...
The hydrogenase from Paracoccus denitrlficans, which is an intrinsic membrane protein, has been s... more The hydrogenase from Paracoccus denitrlficans, which is an intrinsic membrane protein, has been solubilised from membranes by Triton X-100. The partial specific volume of the solubilised protein has been determined using sucrose density gradient centrifugation in H20 and 2H20. The values of the specific volumes of hydrogenase, measured in the presence or absence of Trifon X-100, are 0.73 and 0.74 ml . g-', respectively, indicating that hydrogenase binds much less than one micelle of Triton X-100. The sedimentation coefficient of hydrogenase is increased from 10.4 S to 15.9 S on removal of detergent. The Stokes' radius of hydrogenase, determined by gel filtration on Sepharose 6B, is 5.5 nm in the presence of Triton X-100 compared to 6.7 nm in the absence of detergent. The apparent molecular weight therefore increases from 242 500 to 466000 on removal of detergent.
Classical complement pathway is an important innate immune mechanism, which is usually triggered ... more Classical complement pathway is an important innate immune mechanism, which is usually triggered by binding of C1q to immunoglobulins, pentraxins and other target molecules. Although the activation of the classical pathway is crucial in the host defence, its undesirable and uncontrolled activation can lead to tissue damage. Thus, understanding the molecular basis of complement activation and its inhibition are of great biomedical importance. Recently, we proposed a mechanism for target recognition and classical pathway activation by C1q, which is likely governed by calcium-controlled reorientation of macromolecular electric moment vectors. Here we sought to define the mechanism of C1q inhibition by low molecular weight disulphate compounds that bind to the globular (gC1q) domain, using experimental, computational docking and theoretical modelling approaches. Our experimental results demonstrate that betulin disulphate (B2S) and 9,9-bis(4'-hydroxyphenyl)fluorene disulphate (F2S) inhibit the interaction of C1q and its recombinant globular modules with target molecules IgG1, C-reactive protein (CRP) and long pentraxin 3 (PTX3). In most C1q-inhibitor docked complexes, there is a reduction of electric moment scalar values and similarly altered direction of electric/dipole moment vectors. This could explain the inhibitory effect by impaired electrostatic steering, lacking optimal target recognition and formation of functional complex. In the presence of the inhibitor, the tilt of gC1q domains is likely to be blocked by the altered direction of the electric moment vector. Thus, the transition from the inactive (closed) towards the active (open) conformation of C1q (i.e. the complement activation signal transmission) will be impaired and the cascade initiation disrupted. These results could serve as a starting point for the exploration of a new form of 'electric moment inhibitors/ effectors'.
Classical complement pathway is an important innate immune mechanism, which is usually triggered ... more Classical complement pathway is an important innate immune mechanism, which is usually triggered by binding of C1q to immunoglobulins, pentraxins and other target molecules. Although the activation of the classical pathway is crucial in the host defence, its undesirable and uncontrolled activation can lead to tissue damage. Thus, understanding the molecular basis of complement activation and its inhibition are of great biomedical importance. Recently, we proposed a mechanism for target recognition and classical pathway activation by C1q, which is likely governed by calcium-controlled reorientation of macromolecular electric moment vectors. Here we sought to define the mechanism of C1q inhibition by low molecular weight disulphate compounds that bind to the globular (gC1q) domain, using experimental, computational docking and theoretical modelling approaches. Our experimental results demonstrate that betulin disulphate (B2S) and 9,9-bis(4'-hydroxyphenyl)fluorene disulphate (F2S) inhibit the interaction of C1q and its recombinant globular modules with target molecules IgG1, C-reactive protein (CRP) and long pentraxin 3 (PTX3). In most C1q-inhibitor docked complexes, there is a reduction of electric moment scalar values and similarly altered direction of electric/dipole moment vectors. This could explain the inhibitory effect by impaired electrostatic steering, lacking optimal target recognition and formation of functional complex. In the presence of the inhibitor, the tilt of gC1q domains is likely to be blocked by the altered direction of the electric moment vector. Thus, the transition from the inactive (closed) towards the active (open) conformation of C1q (i.e. the complement activation signal transmission) will be impaired and the cascade initiation disrupted. These results could serve as a starting point for the exploration of a new form of 'electric moment inhibitors/ effectors'.
C1q is the target recognition protein of the classical complement pathway and a major connecting ... more C1q is the target recognition protein of the classical complement pathway and a major connecting link between innate and acquired immunity. As a charge pattern recognition molecule of innate immunity, C1q can engage a broad range of self and non-self ligands via its heterotrimeric globular (gC1q) domain and thus trigger the classical pathway. The trimeric gC1q signature domain has been identified in a variety of non-complement proteins that can be grouped together as a C1q family. The X-ray crystal structures of the gC1q domain of a few members of the C1q family reveal a compact jelly-roll b-sandwich fold similar to that of the multifunctional tumor necrosis factor (TNF) ligand family, hence the C1q and TNF superfamily. This review is an update on the structural and functional aspects of the gC1q domain of human C1q. We also mention the diverse range of proteins that utilize a gC1q domain in order to reflect on its importance as a versatile scaffold to support a variety of functions.
Objective: In the present work the concentration of abnormal immune complexes, cryoglobulins (Cgs... more Objective: In the present work the concentration of abnormal immune complexes, cryoglobulins (Cgs), in the blood of schizophrenic patients was determined, and immunochemical composition of these complexes was studied.
... exploited such that they can be used for numerous applications ranging from sensors and actua... more ... exploited such that they can be used for numerous applications ranging from sensors and actuators ... and materials that offer benefits to both constituencies [2]. The discovery of carbonnanotubes (CNTs) has ... in detail in a separate section latter) such as small size and mass, high ...
Human complement regulatory (also called inhibitory) proteins control misdirected attack of compl... more Human complement regulatory (also called inhibitory) proteins control misdirected attack of complement against autologous cells. Trypanosome and schistosome parasites which survive in the host vascular system also possess regulators of human complement. We have shown Sh-TOR, a protein with three predicted transmembrane domains, located on the Schistosoma parasite surface, to be a novel complement regulatory receptor. The N-terminal extracellular domain, Sh-TOR-ed1, binds the complement protein C2 from human serum and specifically interacts with the C2a fragment. As a result Sh-TOR-ed1 pre-incubated with C2 inhibits classical pathway (CP)mediated haemolysis of sheep erythrocytes in a dose-dependent manner. In CP-mediated complement activation, C2 normally binds to C4b to form the CP C3 convertase and Sh-TOR-ed1 has short regions of sequence identity with a segment of human C4b. We propose the more appropriate name for TOR of CRIT (complement C2 receptor inhibitory trispanning).
Pregnancy-associated plasma protein-A (PAPP-A), like alpha 2-macroglobulin (alpha 2M), is a large... more Pregnancy-associated plasma protein-A (PAPP-A), like alpha 2-macroglobulin (alpha 2M), is a large protein with homotetrameric molecular conformation. Each monomer has Mr 205 kDa. Total carbohydrate content of PAPP-A (19.4%) exceeded that of alpha 2M (8.6%). In addition to glucose (9.4%), fucose (3.1%), mannose (2.3%) and galactose (0.8%), PAPP-A contained glucuronic acid (3.8%). The amino acid composition of PAPP-A differed most significantly from alpha 2M, in the content of glutamate, glycine and lysine. Although the peptide core of both proteins were of similar size, the difference in size, of native molecules was due to the carbohydrate moiety. Whereas alpha 2M monomer was autolytically cleaved into two smaller non-identical subunits (Mr 128 and 65 kDa), no such breakdown products were observed with PAPP-A. Unlike alpha 2M, PAPP-A is not a broad spectrum protease inhibitor. Both proteins inhibited human granulocyte elastase (HGE) in a dose dependent relationship, with PAPP-A (Ki 0.2 x 10(-6) M) being a more potent inhibitor than alpha 2M (Ki 1.02 x 10(-6) M). Since PAPP-A lacked internal thiolester groups, the mechanism of HGE inhibition was unlikely to be entrapment, as defined for alpha 2M. Inhibition kinetics of HGE for PAPP-A (noncompetitive inhibitor) and alpha 2M (uncompetitive inhibitor) were distinct. Thus, these findings do not support the tenet of a common ancestral protein for PAPP-A and alpha 2M.
... THE COMPLEMENT GENES R. Duncan Campbell, SK Alex Law, Kenneth BM Reid, and Robert B. Sim Medi... more ... THE COMPLEMENT GENES R. Duncan Campbell, SK Alex Law, Kenneth BM Reid, and Robert B. Sim Medical Research Council Immunochemistry Unit, Department of Bioн chemistry, University of Oxford, South Parks Road, Oxford OXI 3QU, United Kingdom INTRODUCTION ...
Deposition of amyloid in pancreatic islets is a common feature in human type 2 diabetic subjects ... more Deposition of amyloid in pancreatic islets is a common feature in human type 2 diabetic subjects but because of its insolubility and low tissue concentrations, the structure of its monomer has not been determined. We describe a peptide, of calculated molecular mass 3905 Da, that was a major protein component of amyloid-rich pancreatic extracts of three type 2 diabetic patients. After collagenase treatment, an extract containing 20-50% amyloid was solubilized by sonication into 70% formic acid and the peptide was purified by gel filtration followed by reverse-phase high-performance liquid chromatography. We term this peptide diabetes-associated peptide, as it was not detected in extracts of pancreas from any of six normal subjects. Diabetes-associated peptide contains 37 amino acids and is 46% identical to the sequences of rat and human calcitonin gene-related peptide, indicating that these peptides are related in evolution. Sequence identities with conserved residues of the insulin A chain were also seen in a 16-residue segment. On extraction, the islet amyloid is particulate and insoluble like the core particles of Alzheimer disease. Their monomers have similar molecular masses, each having a hydropathic region that can probably form β -pleated sheets. The accumulation of amyloid, including diabetes-associated peptide, in islets may impair islet function in type 2 diabetes mellitus.
In this study, we used human tonsils for the isolation of the 60 kD component of the Ro/SSA autoa... more In this study, we used human tonsils for the isolation of the 60 kD component of the Ro/SSA autoantigen, following the method described by Wu et al. (J Immunol Methods 1989; 121:219-24).
The IL-1 receptor antagonist (IL-1RN) is a protein that binds to IL-1 receptors and inhibits the ... more The IL-1 receptor antagonist (IL-1RN) is a protein that binds to IL-1 receptors and inhibits the binding of IL-1 alpha and IL-1 beta. As a consequence, the biological activity of these two cytokines is neutralized in physiological and pathophysiological immune and inflammatory responses. In this study, using a panel of somatic rodent-human cell hybrids, we show that the gene for the human interleukin-1 receptor antagonist (IL1RN) maps to the long arm of chromosome 2. Previously, we described a length variation polymorphism within the second intron of the IL-1RN gene (Steinkasserer et al., 1991, Nucleic Acids Res. 19: 5095). Segregation of this, together with an IL-1 alpha polymorphism, was followed in a panel of five CEPH families. Linkage analysis permitted the mapping of the IL-1RN gene to band q14-q21 in the region for the IL-1 alpha and IL-1 beta loci. This study supports the view that an early gene duplication event resulted in the creation of an interleukin-1 gene family.
Complement C3 is a central component of the humoral immune system. Upon triggering of the complem... more Complement C3 is a central component of the humoral immune system. Upon triggering of the complement cascade, proteolytic fragments of C3 mediate important processes such as opsonization and lymphocyte activation. C3 possesses an internal thioester that mediates covalent attachment of proteolytically activated C3 to target surfaces. Treatment of native C3 with methylamine cleaves the thioester bond and exposes a free sulfhydryl group at the targetbinding face of the protein. Through the use of sulfhydryl-reactive heterobifunctional crosslinking and biotinylation reagents, we demonstrate the capacity to form stable, multimeric whole human C3-protein conjugates in a fashion reflecting the orientation of physiologicallyactivated C3. We speculate that this C3 conjugation strategy presents a route for targeting dendritic cells and macrophages. In addition, manipulation of the thioester bond could enhance the study of biological roles of C3 and related proteins such as C4, and also of transmissible agents that exploit complement function such as prions.
... Marilyn S. Rugg(Author), Caroline M. Milner(Author), Jens Madsen(Author), Uffe Holmskov(Autho... more ... Marilyn S. Rugg(Author), Caroline M. Milner(Author), Jens Madsen(Author), Uffe Holmskov(Author), R. Duncan Campbell(Author), Caroline M. Milner(Author), Begoña Aguado(Author), SK Alex Law(Author), A. Neil Barclay(Author), Michael C. Carroll(Author), Lisa A. Steiner ...
European journal of biochemistry / FEBS, Jan 15, 1986
Solution scattering experiments using both X-rays and neutrons are reported for human complement ... more Solution scattering experiments using both X-rays and neutrons are reported for human complement component C3 and up to six other glycoprotein fragments that are derived from C3. The X-ray and neutron molecular masses and neutron matchpoints are in agreement with the known primary sequence of C3. The X-ray radius of gyration RG of C3 is 5.2 nm and is similar for the related forms C3u, C3(a + b) and C3b. The X-ray cross-sectional radius of gyration RXS of C3b is however less than that of C3, C3u and C3(a + b). The major fragments of C3b, namely C3c and C3dg, were studied. The RG of C3c is 4.7 nm and for C3dg is 2.9 nm. C3c and C3dg do not interact when they coexist in solution in equimolar amounts. When C3u is cleaved into iC3u, the RG of iC3u increases to 5.9 nm and its RXS decreases, showing that C3c and C3dg behave as independent entities within the parent glycoprotein. Analyses of the neutron RG and RXS values by contrast variation techniques confirm the X-ray analyses, and show ...
The hydrogenase from Paracoccus denitrlficans, which is an intrinsic membrane protein, has been s... more The hydrogenase from Paracoccus denitrlficans, which is an intrinsic membrane protein, has been solubilised from membranes by Triton X-100. The partial specific volume of the solubilised protein has been determined using sucrose density gradient centrifugation in H20 and 2H20. The values of the specific volumes of hydrogenase, measured in the presence or absence of Trifon X-100, are 0.73 and 0.74 ml . g-', respectively, indicating that hydrogenase binds much less than one micelle of Triton X-100. The sedimentation coefficient of hydrogenase is increased from 10.4 S to 15.9 S on removal of detergent. The Stokes' radius of hydrogenase, determined by gel filtration on Sepharose 6B, is 5.5 nm in the presence of Triton X-100 compared to 6.7 nm in the absence of detergent. The apparent molecular weight therefore increases from 242 500 to 466000 on removal of detergent.
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Papers by Robert Sim