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At least 775 records · Page 43Linked to original sources
PubMed2003

Immunoglobulins against gp273, the ligand for sperm-egg interaction in the mollusc bivalve Unio elongatulus, are directed against charged O-linked oligosaccharide chains bearing a Lewis-like structure and interact with epitopes of the human zona pellucida.

In oocytes of the mollusc bivalve Unio elongatulus, gp273 is the ligand molecule for sperm-egg interaction and binding is mediated by its O-glycans. A serum raised against this protein enabled its localization in the crater region, the area of the vitelline coat where sperm recognition occurs, and showed that after cyanogen bromide fragmentation, the anti-gp273 epitope(s) was retained by a peptide where the O-glycans are localized. In this article, we utilized purified anti-gp273 immunoglobulins to characterize the corresponding epitope by: (i) immunoblotting analysis of the protein after removal of O- and N-glycans; (ii) solid phase binding analysis of anti-gp273 IgG to gp273 N- and O-glycans; and (iii) binding analysis of the same antibody to commercially available oligosaccharides. The results showed that the epitope consists of O-glycans and contains a Lewis-like structure with fucose as determinant. Anti-gp273 IgG were then used to investigate human zona pellucida by immunoelectronmicroscopy and immunoblotting. Epitopes recognized by the antibody were demonstrated on the outer surface of the zona pellucida and shown to belong to a zona pellucida protein having electrophoretic mobility similar to human ZP3. Since human sperm specifically bind to gp273, and anti-gp273 interferes with this binding a functional role for these epitopes is suggested.

Animals↗
PubMed1995

The transcriptional activator protein FIS: DNA interactions and cooperative interactions with RNA polymerase at the Escherichia coli rrnB P1 promoter.

The E. coli rrnB P1 promoter owes its strength, in part, to the transcriptional activator protein FIS. FIS binds to three sites upstream of the RNA polymerase (RNAP) binding site and increases transcription in vivo four to ten-fold. In this report, hydroxyl radical and DMS footprinting analyses show that FIS binds to its three sites along one side of the DNA helix, and that FIS bound at the promoter-proximal site (site I) and RNAP bound at the promoter are in close proximity. The binding of FIS at site I and RNAP at the promoter are mutually cooperative. These observations support a model for direct interaction between the FIS protein bound at site I and RNAP in transcription activation at rrnB P1. We also find that FIS does not bind cooperatively to its three sites upstream of rrnB P1, and that the relatively small activation associated with FIS bound at sites II and III does not result indirectly by facilitation of binding of FIS to site I.

Base Sequence↗
PubMed1980

Genetic interactions in the control of mitochondrial functions in Paramecium. I. Interactions between nuclear genes.

The genetic and physiological properties of two nuclear mutants of Paramecium tetraurelia affecting mitochondrial properties, and first screened as resistant to tetrazolium (TTC) are described. The mutant TTC64-1R is strongly deficient in cytochrome c and the mutant TTC66pR is partially deficient in cytochrome aa3; both mutants display cyanide insensitive respiration in exponential growth phase. In the double mutant TTC64-1R -- TTC66pR/TTC64-1R -- TTC66pR the deficiency in cytochrome aa3 due to the TTC66pR mutation is suppressed. The mutation TTC64-1R does not suppress cytochrome aa3 deficiencies due to mitochondrial mutations, but does interact with another nuclear mutation, cl1, (compatible only with mitochondria deficient in cytochrome oxidase) in such a way that the double mutant TTC64-1R -- cl1/TTC64-1R -- cl1 displays a normal amount of cytochrome aa3. The possible mechanisms and physiological significance of these suppressive effects are discussed.

Animals↗
PubMed2000

Allele-specific interactions between the yeast RFC1 and RFC5 genes suggest a basis for RFC subunit-subunit interactions.

Replication factor C (RFC) is an essential, multi-subunit ATPase that functions in DNA replication, DNA repair, and DNA metabolism-related checkpoints. In order to investigate how the individual RFC subunits contribute to these functions in vivo, we undertook a genetic analysis of RFC genes from budding yeast. We isolated and characterized mutations in the RFC5 gene that could suppress the cold-sensitive phenotype of rfc1-1 mutants. Analysis of the RFC5 suppressors revealed that they could not suppress the elongated telomere phenotype, the sensitivity to DNA damaging agents, or the mutator phenotype of rfc1-1 mutants. Unlike the checkpoint-defective rfc5-1 mutation, the RFC5 suppressor mutations did not interfere with the methylmethane sulfonate- or hydroxyurea-induced phosphorylation of Rad53p. The Rfc5p suppressor substitutions mapped to amino acid positions in the conserved RFC box motifs IV-VII. Comparisons of the structures of related RFC box-containing proteins suggest that these RFC motifs may function to coordinate interactions between neighboring subunits of multi-subunit ATPases.

Alleles↗
PubMed2005

Interaction of polysorbate 80 with erythropoietin: a case study in protein-surfactant interactions.

PURPOSE: The cause of antibody positive pure red cell aplasia associated with the subcutaneous administration of EPREX to patients with chronic kidney failure has been determined to be due to the leaching of weakly adjuvant compounds from the uncoated rubber stoppers that were formerly used in prefilled syringes. Other researchers have suggested that polysorbate 80 micelles containing erythropoietin may be a causative factor. The purpose of this work was to repeat previously published studies in a more controlled manner and to define the precise nature of the interactions between polysorbate 80 and erythropoietin. METHODS: The contents of EPREX prefilled syringes and laboratory-prepared, well-characterized formulations of EPREX were analyzed by size exclusion chromatography. Fractions were analyzed for the presence of erythropoietin by ELISA. EPREX formulations prepared with increasing amounts of polysorbate 80 were analyzed by light scattering. RESULTS: Well-controlled chromatographic studies showed that when EPREX formulations containing no aggregate were analyzed by high-performance liquid chromatography, erythropoietin monomer could not be detected under the polysorbate 80 peak. Dimer and oligomers of erythropoietin coeluted under the polysorbate 80 peak as the molecular weights overlapped on the size exclusion chromatogram. Solution light scattering indicated that polysorbate 80 associates with erythropoietin in a defined stoichiometric ratio of 1:12. CONCLUSIONS: Based on controlled studies, previous results suggesting that EPREX contains micelle-associated erythropoietin were incorrect. As with other surfactants and proteins, polysorbate 80 associates with erythropoietin in a defined stoichiometric ratio.

Chromatography, Gel↗
PubMed1976

Lectin-receptor interactions in liposomes. II. Interaction of wheat germ agglutinin with phosphatidylcholine liposomes containing incorporated monosialoganglioside.

Bovine brain gangliosides incorporated into phospholipid liposomes provide receptors for wheat germ agglutinin. Purified monosialogangliosides were mixed with egg phosphatidylcholine, and unilamellar liposomes were generated. Addition of wheat germ agglutinin induced the liposomes to fuse, and gel filtration analysis revealed that the lectin was incorporated into the fused liposomes. The fusion process was studied by following the changes in the 90 degrees light scattering. Increasing the proportion of the monosialoganglioside in the liposomes was found to increase both the extent of the lectin-induced liposome fusion and the rate of the reaction; below a threshold of approx. 5 mol%, the process was extremely slow. The increase in light scattering could be prevented by the addition of the hapten inhibitor, N-acetyl-D-glucosamine (1 mM). Addition of the inhibitor, subsequent to the lectin, caused a partial decrease in light scattering due to the dissociation of unfused vesicle aggregates. Electron microscopic examination revealed that the ganglioside-containing liposomes were vesicles, 244 +/- 25 A (S.D.) in diameter. Upon addition of wheat germ agglutinin, the vesicles appeared to fuse to form larger vesicles, corresponding to dimers and trimers of the initial vesicles. Inhibition studies with a variety of monosaccharides indicated that the sialic acid moieties present in the ganglioside acted as the lectin-receptor sites. This was confirmed by the observation that wheat germ agglutinin did not interact with phosphatidylcholine vesicles containing desialyated ganglioside.

Binding Sites↗
PubMed1983

Theoretical conformational analysis of phospholipids. I. Study of the interactions between phospholipid molecules by use of semi-empirical methods with the explicit introduction of polar headgroup interactions.

We present a theoretical conformational analysis of a system composed of seven dipalmitoylphosphatidylethanolamine molecules in interaction. The combined use of classical semi-empirical methods for the polar headgroup region with mechanical statistical calculations for the aliphatic chains permits the evaluation of the free energy for a phospholipids molecule. The free energy variation in function of the mean intermolecular interchain distance gives information about the main lipid bilayer phase transition. It appears, however, necessary to take into account the hydration of the polar headgroups.

Calorimetry↗
PubMed1984

Anesthetic-protein interaction. Random versus helix polylysine monolayers and interaction with 1-alkanols.

Penetration of 1-alkanols into monolayers of hydrophobic polypeptides, poly(epsilon-benzyloxycarbonyl-L-lysine) and poly(epsilon-benzyloxycarbonyl-DL-lysine), was compared with their adsorption on the air/water interface in the absence of monolayers. The polypeptide prepared from L-lysine is generally considered to be in the alpha-helical form whereas DL-copolymer polypeptide contains random-coiled portions due to the structural incompatibility between the two isomers. The free energy of adsorption of 1-alkanols on the air/water interface at dilute concentrations was -0.68 kcal X mol-1 per methylene group and 0.15 kcal X mol-1 for the hydroxyl group at 25 degrees C. In the close-packed state, the surface area occupied by each molecule of 1-alkanols of varying carbon chain-lengths showed nearly a constant value of about 27.2 A2, indicating perpendicular orientation of the alkanol molecules at the interface. About 75% of the water surface was covered by 1-butanol in this close-packed state. The mode of adsorption of 1-alkanols on the vacant air/water interface followed the Gibbs surface excess while the mode on the polypeptide membranes followed the Langmuir adsorption isotherm, indicating that the latter is characterized by the presence of a finite number of binding sites. The free energies of adsorption of 1-alkanols on the L-polymer monolayers were more negative than those on the vacant air/water interface and less negative than those on the DL-copolymer monolayers. Thus, the affinity of 1-alkanols to the interface was in the order of vacant air/water interface less than L-polymer less than DL-copolymer. The difference between the air/water interface and L-polymer was about 0.54 kcal X mol-1 and that between L-polymer and DL-copolymer was 0.17 kcal X mol-1 at 25 degrees C: the adsorption of 1-alkanols to the DL-copolymer was favored compared to the L-polymer. The polar moieties of the backbone of the DL-copolymer may be exposed to the aqueous phase at the disordered portion. Dipole interaction between this portion and 1-alkanol molecules may account for the enhanced adsorption of the alkanols to the DL-copolymer.

Adsorption↗
PubMed1987

Consequences of the interaction of calcium with dioleoylphosphatidate-containing model membranes: calcium-membrane and membrane-membrane interactions.

Calcium binds to dioleoylphosphatidate/dioleoylphosphatidylcholine (DOPA/DOPC) (20:80, mol%) multilamellar vesicles in the presence of a calcium ionophore with stoichiometry of about 0.6 nmol calcium per nmol phosphatidate and an apparent dissociation constant of about 1.7 mM. Experiments on the behaviour of monomolecular films at an air/water interface show that calcium-phosphatidate binding results in a decrease in the area of the polar region of the phosphatidate molecule, probably caused by headgroup dehydration and partial charge neutralization. At calcium concentration higher than about 3 mM calcium neutralizes the negatively charged membrane surface of DOPA/DOPC (20:80, mol%) large unilamellar vesicles, and vesicle aggregation is observed. At 10 mM of calcium this results in a low level of vesicle fusion. These observed processes are not attended with calcium-induced phosphatidylcholine transbilayer movement in the membranes of DOPA/DOPC (20:80, mol%) large unilamellar vesicles. When these findings are compared with the results of a previous study on the permeability behaviour of large unilamellar vesicles of the same phospholipid composition under comparable conditions (Smaal, E.B., Mandersloot, J.G., De Kruijff, B. and De Gier, J. (1986) Biochim. Biophys. Acta 860, 99-108) the following conclusions can be drawn. At low millimolar calcium concentrations (less than 2.5 mM) calcium does not occupy all the binding sites of the membrane, no membrane-membrane interactions are observed and a selective translocation of calcium and calcium-chelating anions is appearing. The mechanism of this translocation may be explained by the formation of uncharged dehydrated complexes of calcium, phosphatidate and calcium chelator, which can pass the membrane via transient occurring non-bilayer structures. Between 3 and 10 mM of calcium an a selective permeability increase of the vesicular membrane is found, which is not a consequence of vesicle fusion but apparently of vesicle aggregation, possibly causing packing defects in the membrane.

Calcimycin↗
PubMed1978

Thyroxine-protein interactions. Binding constants for interaction of thyroxine analogues with the thyroxine binding site on human thyroxine-binding globulin.

The binding constants for interaction of various thryoxine analogues with the thyroxine binding site on human thyroxine-binding globulin have been determined. Equilibrium dialysis, at pH 7.4 and 37 degrees C, was used to measure the competitive effects of different iodothyronine compounds on the binding of 125I-labeled thyroxine to highly purified thyroxine-binding globulin. Relative to L-thyroxine, K = 6 . 10(9) M-1, the association constants of some important analogues were D-thyroxine, 1.04 . 10(9) M-1, 3,5-diiodo-3'-isopropyl-L-thyronine, 4.9 . 10(8) M-1; L-triiodothyronine, 3.3 . 10(8) M-1, 3,3',5'-DL-triiodothyronine (reverse triiodothyronine), 3.1. 10(8) M-1; tetraiodothyropropionic acid, 2.7 . 10(8) M-1; tetraiodothyroacetic acid, 2.6 . 10(8) M-1; 3', 5'- diiodo-DL-thyronine, 8.3 . 10(7) M-1; and 3,5-diiodo-DL-thyronine, 7.1 . 10(7) M-1. Calculation of the deltaG0 values for binding of the analogues indicates that a major contribution to the free energy favoring binding is made by the alanine side chain of thyroxine. A change in configuration of the alpha-amino group from the L to D form causes an unfavorable change of 1 kcal/mol in the free energy of binding. Removal of the alpha-amino group as in tetraiodothyropropionic acid causes an unfavorable change of 1.9 kcal/mol in the free energy of binding. With regard to ring substituents, the results indicate that the two inner 3,5-iodines make about the same contribution to binding as the two outer 3', 5'-iodines.

Binding Sites↗
PubMed1981

pH-dependent interaction of microsomal cytochrome P-450 with substrates. I. Effect of pH upon the interaction of exogenous substrates with membrane-bound cytochrome P-450.

The interaction of microsomal membrane-bound cytochrome P-450 with substrates was studied spectrophotometrically at various pH-values. The binding of type I compounds, hexobarbital and androstanedione, with cytochrome P-450, as determined by the magnitude of the type I spectral change of microsomes, was markedly enhanced at alkaline pH compared to that at acid pH. The pH-dependent spectral change could be reversed by changing the pH. The maximum absorption change (delta Amax) increased with increasing the pH, while the spectral dissociation constant (Ks) decreased. A similar pH-dependent binding reaction was also observed using a non-dissociative type I compound, cyclohexane. On the contrary, the absorbance magnitude between peak and trough in the aniline- or alcohol-induced difference spectrum of microsomes was enhanced by decreasing the pH, indicating easy complex formation of type II and reverse type I compounds with cytochrome P-450 in the acid rather than the alkaline region.

Aniline Compounds↗
PubMed1988

Role of peptide structure in lipid-peptide interactions: nuclear magnetic resonance study of the interaction of pentagastrin and [Arg4]pentagastrin with dimyristoylphosphatidylcholine.

Complexes formed between dimyristoylphosphatidylcholine (DMPC) and the peptide pentagastrin or [Arg4]pentagastrin were examined by 31P- and 2H-NMR. The cationic [Arg4]pentagastrin produces larger changes in the lipid NMR spectra than does the anionic pentagastrin. 31P-NMR spectra of DMPC with [Arg4]pentagastrin below the phase transition exhibits two components one of which is motionally restricted compared with the pure lipid. The exchange between these two lipid domains is slow on the millisecond time scale. The interactions between this peptide and phospholipid are diminished above the melting temperature of the complex. The 2H-NMR spectra of DMPC which had been labelled in a choline methylene group is also affected more by the [Arg4]pentagastrin than by pentagastrin. In the presence of [Arg4]pentagastrin, even above the lipid phase transition, an additional doublet with a smaller quadrupole splitting is observed. These results clearly demonstrate the importance of peptide charge in determining the effects of peptides on lipid bilayers.

Dimyristoylphosphatidylcholine↗
PubMed1986

Mnemonic aspects of Escherichia coli DNA polymerase I. Interaction with one template influences the next interaction with another template.

When Escherichia coli DNA polymerase I (Pol I) replicates a homopolymer, the excision/polymerization (exo/pol) ratio varies with enzyme and initiator concentration. The study of this effect in the case of poly(dA).oligo(dT) replication led us to propose a mnemonic model for Pol I, in which the 3' to 5' excision activity warms up when the enzyme is actively polymerizing, and cools down when it dissociates from the template. The model predicts that the exo/pol ratio must increase with processivity length and initiator concentration and decrease with enzyme concentration. It predicts also that contact of the enzyme with one template alters its excision efficiency towards another template. The exo/pol ratio and processivities of Pol I and its Klenow fragment were studied on four templates: poly(dA).(dT)10, poly(dT).(dA)10, poly(dC).(dG)10 and poly(dI).(dC)10. We show that the Klenow fragment is usually much less processive than Pol I and when this is the case it has a much lower exo/pol ratio. At equal processivity, the exo/pol ratios are nearly equal. Furthermore, many factors that influence processivity length (e.g. manganese versus magnesium, inorganic pyrophosphate, ionic strength) influence the exo/pol ratio in the same direction. The study of deaminated poly(dC) replication, where we followed incorporation and excision of both G and A residues, allowed us to assign the origin of the dNMP variations to changes in the 3' to 5' proof-reading activity of Pol I. Similarly, the lower dNMP turnover of the Klenow fragment observed with deaminated poly(dC) was specifically assigned to a decreased 3' to 5' exonuclease activity. The exo/pol ratio generally increased with initiator and decreased with enzyme concentration, in agreement with the model, except for poly(dI).oligo(dC), where it decreased with initiator concentration. However, by terminating chain elongation with dideoxy CTP, we showed directly that, even in this system, excision is relatively inefficient at the beginning of synthesis. Interaction of Pol I with poly(dA).(dT) or with poly(dC).(dG) modifies its exo/pol characteristics in the replication of poly(dI).(dC) and poly(dA).(dT), respectively. The Klenow enzyme is not sensitive to such influences and this correlates with its reduced processivity on the influencing templates. Our results reveal the existence of differences between Pol I and its Klenow fragment that are more profound than has been thought previously.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Composition↗
PubMed1996

Interaction of Ca2(+)-activated K+ channels with refolded charybdotoxins mutated at a central interaction residue.

Charybdotoxin is a small peptide blocker of K+ channels, rigidly held in active conformation by three disulfide bonds. The toxin blocks K+ channels by binding to a receptor site located at the external "vestibule", and thus physically occluding the outer opening of the K+ conduction pore. In the blocked complex, K27, a residue on the toxin's molecular surface, projects its epsilon-amino group into the K(+)-selective pore. The results here show that CTX, produced by heterologous expression in E. coli, may be manipulated to place unnatural positively charged residues at position 27. The toxin folds faithfully to its native conformation when the crucial lysine at position 27 is replaced by a cysteine residue, a maneuver that allows specific chemical modification of this side-chain. Replacements of K27 by side-chains slightly shorter or slightly longer than lysine yield active toxins. The toxin variant with ornithine at this position interacts much less strongly with K+ ions in the pore of slowpoke-type Ca2(+)-activated K+ channels than does wild-type toxin. This result argues that the epsilon-amino group of K27 in bound toxin lies only a few ångstroms away from a K+ ion occupying the blocked pore. The peptide folds with high efficiency to form the correct disulfides even in the presence of strong denaturants.

Charybdotoxin↗
PubMed1983

The interaction between collagens and factor VIII/von Willebrand factor: investigation of the structural requirements for interaction.

The blood protein Factor VIII/von Willebrand factor (FVIII/VWF) has been shown to bind to a variety of collagen polymers including (i), the native-type fibres (of collagens types I and III), (ii), segment-long-spacing (SLS) aggregates (of collagens types I, III, IV and V), (iii), the insoluble polymer obtained by random cross-linking of the type I monomer and (iv), the non-striated fibril (of type I) produced by alcohol precipitation. Relatively little binding of FVIII/VWF to the amorphous, non-fibrillar form of collagen (type I) produced by salt precipitation from acid solution was observed. No significant binding either to elastin or to the insoluble polymer derived by random cross-linking of bovine serum albumin was noted. The absorption of FVIII/VWF to collagens was affected by ionic concentration and FVIII/VWF was only totally bound at relatively low ionic strength. Binding of radiolabelled FVIII/VWF could be largely inhibited by an excess of the unlabelled protein. The interaction of FVIII/VWF with collagen fibres was inhibited in a concentration-dependent manner by monomeric collagen when present at relatively high concentrations. Gelatin did not appear to inhibit binding significantly. The structural requirements of collagen for binding to occur appear to resemble those required for collagen-induced platelet aggregation in which collagen quaternary structure rather than collagen type per se is the important factor. Loss of secondary or higher orders of structure of FVIII/VWF as a result of heat denaturation or reduction of disulphide bonds decreased or prevented binding. In accord with the association of biological activity with FVIII/VWF aggregates, optimal binding appeared to require the presence of aggregated FVIII/VWF.

Binding, Competitive↗
PubMed1994

Thiotungstate-copper interactions. I. Studies on the metabolism of [185W] tetrathiotungstate and the systemic interactions of labeled pharmacological doses with copper in rats.

[185W] tetrathiotungstate was employed to study the metabolism of thiocompounds in rats after i.v. injection. At tracer levels (12.5 micrograms W) the most important plasma binding protein eluted in the position of ceruloplasmin but the association did not prevent uptake of thiotungstate by the liver. At higher dose levels (1.5 mg W) there was considerable hydrolysis immediately after injection with rapid excretion of label in urine. The [185W] tetrathiotungstate remaining in plasma was associated with albumin and the amount retained was increased by pretreatment of the rats with copper. The increased binding to albumin did not prevent hepatic uptake and over the short-term pretreatment with copper increased the movement of the isotope into subcellular organelles, probably lysosomes. The excretion in bile was increased and the label was associated with high molecular weight proteins. In liver cytosol the 185W was bound by specific, as yet uncharacterized, proteins. At the higher dose levels there was some movement to higher molecular weight proteins and this was greatly increased by the pretreatment with copper. The studies show that the metabolism of 185W tetrathiotungstate is sufficiently similar to 99Mo or 35S tetrathiomolybdate for work on the systemic interactions of thiocompounds and copper in man and animals.

Animals↗
PubMed1996

Investigation of the interaction of m-calpain with phospholipids: calpain-phospholipid interactions.

Phosphatidyl inositol, phosphatidyl choline, phosphatidyl glycerol, phosphatidyl serine, phosphatidyl ethanolamine, phosphatidic acid and sphingomyelin were all found to be effective at reducing the Ca2+ requirement for m-calpain autolysis. In the absence of phospholipid, pig kidney m-calpain required 1.4 mM Ca2+ for 50% autolysis under the assay conditions used. Phospholipids caused a reduction in this Ca2+ requirement to a value between 0.45 mM Ca2+ for phosphatidyl glycerol and 1.1 mM Ca2+ for phosphatidyl ethanolamine. Previous studies (Crawford, C., Brown, N.R. and Willis, A.C. (1990) Biochem. J. 265, 575-579) have shown that the most probable site for phospholipid interaction in calpain is the N-terminal region between residues 39 to 62 of the small subunit of calpain (G17TAMRILGG). In this study we examine the possible role of this G17TAMRILGG region. Three synthetic peptides corresponding to parts of this sequence were used to examine the phospholipid binding sequence. Analysis of the phospholipid vesicle binding properties of these peptides suggested that both the TAMRIL and polyglycine sequences were required for binding to phosphatidyl inositol vesicles.

Amino Acid Sequence↗
PubMed1979

Interaction of phenosafranine with nucleic acids and model polyphosphates. III. Heterogeneity in phenosafranine interactions with DNA base pairs.

Fluorescence and circular dichroism spectral measurements, thermal denaturation studies and binding competition experiments with netropsin and actinomycin D were carried out in systems containing phenosafranine bound to DNA's differing in base composition. The investigated properties exhibit a heterogeneity related to the content of A.T and G.C pairs in DNA and to the nature of phenosafranine binding modes. At low level of saturation of binding sites (r less than 0.1) phenosafranine does not show strong preference for any of the DNA base pairs in the overall binding. However, the strong monomer non-cooperative binding outside the helix (mode I1) occurs predominantly, even though not exclusively in G.C rich regions. The strong binding modes involving intercalated dye molecules (mode I2 and eventually mode II1) prevail in A.T rich regions. These binding modes become the principal types of strong phenosafranine interaction with DNA when the level of saturation of binding sites increases, i.e. at r greater than 0.1.20

Bacillus cereus↗