scholarly journals The interactions of haem with ligandin and aminoazo-dye-binding protein A.

1976 ◽  
Vol 157 (2) ◽  
pp. 461-467 ◽  
Author(s):  
E Tipping ◽  
B Ketterer ◽  
L Christodoulides ◽  
G Enderby
Keyword(s):  
Association Constant ◽  
Protein Complexes ◽  
Binding Protein ◽  
Protein A ◽  
Association Constants ◽  
Dye Binding ◽  
Cotton Effects ◽  
Haem Protein ◽  
Haem Iron ◽  
Soret Region

1. The interactions of ferriprotoporphyrin IX with ligandin and aminoazo-dye-binding protein A result in absorption spectra in the Soret region characteristic of the ligand in its monomeric state. 2. Both proteins are able to bind ferrous as well as ferric haem. 3. Ferriprotoporphyrin IX is bound at a single site on both proteins. At pH7.0, I 0.16M, difference-spectrophotometric measurements gave association constants of 10(7) and 4 × 10(6) LITRE/MOL FOR LIGANDIN AND PROTEin A respectively. Under the same conditions fluorescence-quenching experiments gave an association constant of 2 × 10(7) litre/mol for ligandin. 4. Bilirubin, bromosulphophthalein and oesterone sulphate each compete with haem for binding by the two proteins. 5. Ferriprotoporphyrin IX bound to both ligandin and protein A is able to form co-ordination complexes with CN-, but not, to any measurable extent, with either N3- or F-. From these results it is suggested that binding by the two proteins may not involve the haem iron atom. 6. Both haem-protein complexes give rise to measurable extrinsic Cotton effects in the Soret region. 7. The formation and properties of the ligandin- and protein A-haem complexes are compared with those of haem-albumin, haemoglobin, myoglobin and other haemoproteins.

scholarly journals Spectroscopic studies of the binding of bilirubin by ligandin and aminoazo-dye-binding protein A

1976 ◽  
Vol 157 (1) ◽  
pp. 211-216 ◽  
Author(s):  
E Tipping ◽  
B Ketterer ◽  
L Christodoulides ◽  
G Enderby
Keyword(s):  
Association Constant ◽  
Fluorescence Spectra ◽  
Binding Protein ◽  
Protein A ◽  
Spectroscopic Studies ◽  
Absorption And Fluorescence Spectra ◽  
Quantitative Studies ◽  
Dye Binding ◽  
Cotton Effects ◽  
Unbound Bilirubin

Ligandin and aminoazo-dye-binding protein A both bind bilirubin at a single site. Quantitative studies of the interactions using difference spectrophotometry show that at pH 7.0, protein A binds the tetrapyrrole with an association constant (K) greater than or equal to 2 × 10(7) litre/mol, whereas binding by ligandin is slightly weaker (K = 7 × 10(6) litre/mol) at this pH. The protein-bilirubin complexes give rise to absorption and fluorescence spectra quite different from those of unbound bilirubin and also to large Cotton effects. It appears that on binding to both proteins, the ligand is forced into a rigid twisted configuration in a hydrophobic environment. Ligandin and protein A resemble serum albumin in their interactions with bilirubin.

scholarly journals Human Opsonins Induced during Meningococcal Disease Recognize Transferrin Binding Protein Complexes

1999 ◽  
Vol 67 (12) ◽  
pp. 6526-6532 ◽  
Author(s):  
A. K. Lehmann ◽  
A. R. Gorringe ◽  
K. M. Reddin ◽  
K. West ◽  
I. Smith ◽  
...  
Keyword(s):  
Meningococcal Disease ◽  
Oxidative Burst ◽  
Protein Complexes ◽  
Binding Protein ◽  
Protein A ◽  
Enzyme Linked Immunosorbent Assay ◽  
Flow Cytometric ◽  
Fluorescent Beads ◽  
Oxidative Burst Activity ◽  
Vaccine Potential

ABSTRACT Patient serum opsonins against transferrin binding protein A+B (TbpA+B) complexes from two Neisseria meningitidis strains (K454 and B16B6, with 85- and 68-kDa TbpB, respectively) were quantified by a functional phagocytosis and oxidative burst assay. TbpA+B complexes adsorbed to fluorescent beads were opsonized with individual acute and convalescent sera from 40 patients infected by a variety of meningococcal strains. Flow cytometric quantitation of leukocyte phagocytosis products (PP) demonstrated that disease-induced serum opsonins recognized TbpA+B, and the highest anti-TbpA+B serum opsonic activities were found between admission to hospital and 6 weeks later. The PP values obtained with TbpA+B from strain B16B6 (PPB16B6) were higher than those obtained with TbpA+B from strain K454 (PPK454), with both acute and convalescent sera (P < 0.0001), and correlated positively with higher immunoglobulin G enzyme-linked immunosorbent assay titers against TbpA+B from strain B16B6 than from strain K454 (P < 0.001). In spite of considerable variations between individuals, significant correlations were found between the PPB16B6 and PPK454 values, and the PP values did not depend on the variability of the TbpB proteins of the disease-causing strains. Simultaneously measured oxidative burst activity correlated closely with the PP values. We conclude that highly cross-reactive anti-TbpA+B serum opsonins are produced during meningococcal disease. The anti-TbpA+B opsonic activities were not affected by the variability of the TbpB proteins of the disease-causing strains, which further adds to the evidence for the vaccine potential of meningococcal TbpA+B complexes.

scholarly journals Interactions of small molecules with phospholipid bilayers. Binding to egg phosphatidylcholine of some organic anions (bromosulphophthalein, oestrone sulphate, haem and bilirubin) that bind to ligandin and aminoazo-dye-binding protein A

1979 ◽  
Vol 180 (2) ◽  
pp. 327-337 ◽  
Author(s):  
E Tipping ◽  
B Ketterer ◽  
L Christodoulides
Keyword(s):  
Intracellular Transport ◽  
Binding Protein ◽  
Equilibrium Dialysis ◽  
Protein A ◽  
Molar Ratio ◽  
Oestrone Sulphate ◽  
Dye Binding ◽  
Order Of Magnitude ◽  
Saturation Effects ◽  
Limiting Values

1. To assess the possible involvement of ligandin and aminoazo-dye-binding protein A in intracellular transport it is necessary to know how their ligands, most of which are molecules with hydrophobic moieties, interact with cellular membranes. To obtain such information we examined the interactions of bromosulphophthalein, oestrone sulphate, haem and bilirubin with aqueous dispersions of egg phosphatidylcholine and egg phosphatidylchone/cholesterol (1:1, molar ratio) by equilibrium dialysis and spectrophotometry. 2. In all four cases, saturation effects were observed. Values of Vmax (v = mol of compound bound/mol of lipid phosphorus) at 25 degrees C were: for bromosulphophthalein, approximately 0.1; for oestrone sulphate, approximately 0.25; for haem, approximately 0.25 (all at pH 7.4); and for bilirubin 0.1–0.2 (at pH 8.2). 3. Limiting values of v/c (c = unbound concentration) as v leads to 0 at 25 degrees C and pH 7.4 are: for bromosulphophthalein, 6.25 × 10(4) litre-mol-1; for oestrone sulphate, 7.8 × 10(2) litre-mol-1; for haem, 4.5 × 10(5) litre-mol-1; and for bilirubin, approximately 1.2 × 10(4) litre-mol-1. For haem the result depends on the assumption that only the monomeric form binds to the lipid. 4. The binding of each compound was decreased by cholesterol; bromosulphophthalein and oestrone sulphate were affected more than haem and bilirubin. 5. Bromosulphophthalein at saturating concentration decreased the limiting values of v/c of the other three compounds by approximately one order of magnitude. 6. By assuming that the interactions with egg phosphatidylcholine resemble those with the phospholipid components of mammalian intracellular membranes the binding data for phosphyatidylcholine, together with data for binding to the intracellular proteins ligandin and aminoazo-dye-binding protein A, enable the subcellular distributions of the four compounds to be estimated. For the rat hepatocyte up to 92, 51, 98 and 47% of the total bromosulphophthalein, oestrone sulphate, haem and bilirubin respectively may be membrane-bound.

scholarly journals Interactions of small molecules with phospholipid bilayers. Binding to egg phosphatidylcholine of some uncharged molecules (2-acetylaminofluorene, 4-dimethylaminoazobenzene, oestrone and testosterone) that bind to ligandin and aminoazo-dye-binding protein A

1979 ◽  
Vol 180 (2) ◽  
pp. 319-326 ◽  
Author(s):  
Edward Tipping ◽  
Brian Ketterer ◽  
Lucia Christodoulides
Keyword(s):  
Lipid Bilayers ◽  
Partition Coefficients ◽  
Intracellular Transport ◽  
Binding Protein ◽  
Equilibrium Dialysis ◽  
Protein A ◽  
Molar Ratio ◽  
Intracellular Proteins ◽  
Dye Binding ◽  
Membrane Bound

1. To assess the possible involvement of ligandin and aminoazo-dye-binding protein A in intracellular transport it is necessary to know how their ligands, most of which are molecules with hydrophobic moieties, interact with cellular membranes. To obtain such information we have examined the interactions of 2-acetylaminofluorene, 4-dimethylaminoazobenzene, oestrone and testosterone with aqueous dispersions of egg phosphatidylcholine and egg phosphatidylcholine/cholesterol (1:1, molar ratio) by equilibrium dialysis and spectrophotometry. 2. At 25°C and pH7.4, the partition coefficients for binding to phosphatidylcholine [expressed as (mol of ligand bound/mol of phosphatidylcholine)/unbound ligand concentration] were: for 2-acetylaminofluorene, 5.0×103 litre·mol−1; for 4-dimethylaminoazobenzene, 2.1×104 litre·mol−1; for oestrone, 3.1×103 litre·mol−1; and for testosterone, 4.2×102 litre·mol−1. In the ranges studied these values were independent of concentration. The results for the two steroids confirm those of Heap, Symons & Watkins [(1970) Biochim. Biophys. Acta218, 482–495]. 3. The introduction of cholesterol into the lipid bilayers caused large decreases in the partition coefficients of oestrone and testosterone, but had relatively little effect on the binding of 2-acetylaminofluorene and 4-dimethylaminoazobenzene. 4. By assuming that the interactions with egg phosphatidylcholine bilayers resemble those with the phospholipid components of mammalian intracellular membranes the phosphatidylcholine partition coefficients, together with data for binding to the intracellular proteins ligandin and aminoazo-dye-binding protein A, enable the subcellular distributions of the four compounds to be estimated. For the rat hepatocyte up to 98, 99, 89 and 58% of the total 2-acetylaminofluorene, 4-dimethylaminoazobenzene, oestrone and testosterone respectively may be membrane-bound.

Binding of Human Platelet Glycoprotein lb and Actin to Fragments of Actin-Binding Protein

1992 ◽  
Vol 67 (02) ◽  
pp. 252-257 ◽  
Author(s):  
Anne M Aakhus ◽  
J Michael Wilkinson ◽  
Nils Olav Solum
Keyword(s):  
Actin Filaments ◽  
High Speed ◽  
Binding Protein ◽  
Protein A ◽  
Actin Binding ◽  
Platelet Glycoprotein ◽  
Actin Binding Protein ◽  
Crossed Immunoelectrophoresis ◽  
Triton X ◽  
Calpain Inhibitors

SummaryActin-binding protein (ABP) is degraded into fragments of 190 and 90 kDa by calpain. A monoclonal antibody (MAb TI10) against the 90 kDa fragment of ABP coprecipitated with the glycoprotein lb (GP lb) peak observed on crossed immunoelectrophoresis of Triton X-100 extracts of platelets prepared without calpain inhibitors. MAb PM6/317 against the 190 kDa fragment was not coprecipitated with the GP lb peak under such conditions. The 90 kDa fragment was adsorbed on protein A agarose from extracts that had been preincubated with antibodies to GP lb. This supports the idea that the GP Ib-ABP interaction resides in the 90 kDa region of ABP. GP lb was sedimented with the Triton-insoluble actin filaments in trace amounts only, and only after high speed centrifugation (100,000 × g, 3 h). Both the 190 kDa and the 90 kDa fragments of ABP were sedimented with the Triton-insoluble actin filaments.

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