On the modification of conalbumin by acid. I. Electrophoretic and sedimentation studies on conalbumin prepared by ammonium sulfate precipitation from acid solutions.
Explore the source record for details and available documents.
Ammonium Sulfate↗
SEARCH · Search PubMed
Results for “Conalbumin”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
On the modification of conalbumin by acid. II. Effect of pH and salt concentration on the sedimentation behavior, viscosity and osmotic pressure of conalbumin solutions.
Explore the source record for details and available documents.
Conalbumin↗
On the modification of conalbumin by acid. III. Effect of electrolytes on the action of acid on conalbumin.
Explore the source record for details and available documents.
Conalbumin↗
The denaturation of proteins. IV. Conalbumin and iron(III)-conalbumin in urea solution.
Explore the source record for details and available documents.
Albumins↗
Improvements in immunoprecipitation of specific messenger RNA. Isolation of highly purified conalbumin mRNA in high yield.
We have described previously procedures for the isolation of specific mRNA employing immunoprecipitation of polysomes. In spite of our success with ovalbumin mRNA in the chicken oviduct, we have had considerable difficulties in applying these same published techniques to the immunopurification of conalbumin mRNA, despite the fact that the chicken oviduct synthesizes up to 10% of protein as conalbumin. Here we describe a number of modifications and refinements which have proved essential in obtaining intact conalbumin mRNA in high purity and high yields. These refinements include: (a) improved purification of conalbumin in order to remove contaminating proteins that result in impure antibodies; (b) improved isolation of specific conalbumin antibody in high yields; (c) improved methods for reducing contamination by non-specific polysomes; (d) improved techniques for isolation of RNA from immunoprecipitates resulting in less degradation and higher recovery of conalbumin mRNA; (E) improved techniques for efficient translation of conalbumin mRNA involving treatment of the RNA with methylmercury prior to translation. We conclude that problems involved in the immunoprecipitation of different mRNAs may differ, and that various refinements in techniques may be required for obtaining highly purified preparations of intact mRNA in high yields.
Animals↗
Iron binding to conalbumin. Calorimetric evidence for two distinct species with one bound iron atom.
When thermal denaturation of conalbumin solutions partially saturated with Fe(III) is observed by differential scanning calorimetry, four endotherms are observed between 40 and 100 degrees. The relative size of these four endotherms is determined by the Fe(III) to conalbumin ration. At a heating rate of 10 degrees/min, in Tris buffer at pH 7.5, observed endotherm temperature maxima and enthalpies of denaturation are: conalbumin, 63 degrees, 320 kcal/mol; intermediate I, 68 degrees, intermediate I, 77 degrees; Fe2-conalbumin, 84 degrees, 630 kcal/mol. These four endotherms are observed over a range of protein concentration from 7 to 100 mg/ml and are unchanged when excess bicarbonate is present. Stoichiometric calculations of both total protein and total iron indicate that each intermediate endotherm results from denaturation of conalbumin molecules containing only one ferric ion. These experimental results are thus consistent with the presence of two different monomeric one-iron conalbumin intermediates. They strongly suggest that the two iron binding sites of conalbumin are not equivalent.
Animals↗
Conalbumin in the treatment of acute enteritis in the infant.
Conalbumin, a glycoprotein derived from eggwhite, has the property, like lactoferrin, of binding iron ions. This property prompted the authors to undertake an experimental study on acute enteritis in infants in the first year of life. Forty infants with acute enteritis, not complicated by ionic imbalance or severe dehydration, were randomly allocated to two groups. The subjects of the first group were treated with the traditional dietetic therapy; those of the second were treated with the same diet plus conalbumin for periods ranging from 6 to 10 days. General condition, the alvus and body-weight trends were evaluated during and after the treatment period. Stool cultures were also carried out during treatment. In the group of children treated with conalbumin the results were: excellent in 5 subjects (25%), good in 13 (65%), fair in 1 (5%) and null in 1 (5%). The general status and the time needed to normalize the alvus were statistically significant (p less than 0.001) in favour of conalbumin. Body-weight in the two groups showed no significant difference. Neither metabolic alterations nor intolerance phenomena were noted during treatment with conalbumin. In conclusion, conalbumin demonstrated therapeutic properties against acute enteritis in infants through the rapid normalization of the alvus. No side-effects were noted.
Acute Disease↗
Identical precursors for serum transferrin and egg white conalbumin.
The NH2-terminal sequences of egg white conalbumin and chicken serum transferrin were examined and found to be identical. Conalbumin, when synthesized in a rabbit reticulocyte cell-free translation system, was found to contain an NH2-terminal extension of 19 amino acid residues. Sequential Edman degradation of this precursor (pre-conalbumin) labeled with radioactive amino acids revealed the following sequence: formula see text: The vertical line indicates the site at which pre-conalbumin is cleaved to yield authentic conalbumin. The sequence represents the primary translation product since the NH2-terminal methionine was shown to be derived from initiator Met-tRNAfMet. A partial NH2-terminal sequence of transferrin synthesized in vitro was also determined (underlined residues) and it is identical with that of pre-conalbumin.
Amino Acid Sequence↗
Magnetic resonance studies of Mn(II)-, Mn(III)-, and Fe(III)-conalbumin complexes.
Apoconalbumin binds Mn(II) at two sites with association constants of K1 = 7 (+/- 1) X 10(4) and K2 = 0.4 (+/- 0.25) X 10(4) M-1. The binding is tighter in the presence of excess bicarbonate resulting in K1 = 1.8 (+/- 0.2) X 10(5) and K2 = 3 (+/- 2) X 10(4) M-1. The electron paramagnetic resonance spectrum (at both 9 and 35 GHz) of Mn(II) bound at the tight site reveals a rhombic distortion (lambda = E/D approximately equal to 0.25-0.31) in the protein ligand environment of the mental ion. An evaluation of the 1/pT1p, paramagnetic contribution to the longitudinal relaxation rate of solvent protons with Mn(II)-, Mn(III)-, and Fe(III)-derivatives of conalbumin revealed that the mental ion in each site of conalbumin is accessible to one water molecule. For Mn(II)-conalbumin and Mn(III)-conalbumin species, inner coordination sphere protons are rapidly exchanging with the bulk solvent, while slow exchange conditions prevail for Fe(III)-conalbumin.
Conalbumin↗
DNA methylation: correlation with DNase I sensitivity of chicken ovalbumin and conalbumin chromatin.
To analyse the relationship between DNA undermethylation at some sites in the ovalbumin and conalbumin gene regions (1) and the expression of these genes in chick oviduct, digestions with HhaI, which differentiates between methylated and unmethylated HhaI restriction sites, was performed on DNA isolated from chicken erythrocyte or oviduct chromatin treated with DNase I which degrades preferentially "active" chromatin. This was followed by analysis with ovalbumin- and conalbumin-specific hybridization probes. We conclude that the residual DNA methylation found at some sites of the ovalbumin and conalbumin gene regions is derived from the fraction of cells in which the chromatin of these genes is not in an "active" form. On the other hand, the ovalbumin and conalbumin sites which are partially unmethylated in erythrocyte DNA correspond to chromatin regions which are not DNase I-senitive. We have also detected a site about 1 kb downstream from the 3' end of the conalbumin gene that is hypersensitive to DNase I in all tissues tested.
Animals↗
Transcription of the chicken ovalbumin and conalbumin gene during early secondary induction with estrogens.
Estrogens stimulate the rate of transcription of the ovalbumin and conalbumin gene in the chicken oviduct. The synthesis of ovalbumin and conalbumin mRNA was studied in isolated nuclei. RNA synthesized in vitro was distinguished from preexisting nuclear RNA by affinity labeling the in vitro products with a mercurated nucleotide and subsequent purification of the Hg-RNA on SH-agarose. The content of ovalbumin and conalbumin mRNA sequences in the in vitro transcripts was determined by hybridization to cDNA. After the withdrawal of implanted hormones from chickens, the synthesis of conalbumin and ovalbumin RNA increased 2.5- and at least 20-fold, respectively, by treatment with estrogens. The maximal rate of transcription of the conalbumin gene is achieved within 2 h after estrogen induction, whereas the rate of transcription of the ovalbumin gene becomes maximal after a lag of several hours. These results demonstrate that estrogens affect two genes in the same target cell differently.
Amanitins↗
Electron spin echo studies of the copper complexes of conalbumin.
Electron spin echo envelope spectroscopy was used to probe the two metal binding sites of Cu(II)-conalbumin. The echo envelope spectrum of Cu(II)-conalbumin-oxalate, with metal ion at either one or both of the binding sites, contains lines arising from the interaction of the electron spin of Cu(II) with bound imidazole, demonstrating histidine ligation to the metal ion. The 13C superhyperfine interaction of bound [13C]oxalate, obtained from the ratio of the electron spin echo envelopes of Cu(II)-conalbumin-[13C]oxalate to that of Cu(II)-conalbumin-[12C]oxalate, is about twice the free precession frequency and indicates a contact interaction between 13C and Cu(II). This study indicates that oxalate is directly coordinated to the metal ion. Over the pH range 7.0 to 10.0, where Cu(II)-conalbumin binds carbonate as an associated anion, the echo envelope spectrum indicates that at least one imidazole ligand is coordinated to Cu(II). Below pH 6.0 and above pH 11.0, imidazole coordination is not observed.
Binding Sites↗
Effect of conalbumin on phytomitogen stimulation and E-rosette formation of human peripheral lymphocytes in normal subjects.
An immunological in vitro study was carried out on conalbumin, an iron binding protein structurally similar to lactoferrin, which is a well-known bacterial inhibitor in human milk. Conalbumin itself has been proved to have bacteriostatic activity against a broad spectrum of bacteria responsible for gastrointestinal infections. The activity of conalbumin on the in vitro response to PHA, PWM and Con A and on the E-rosette formation ability of peripheral lymphocytes of 10 normal subjects was studied. The results showed that conalbumin did not affect the lymphocytes' E-rosette formation ability and did not induce blastic transformation of lymphocytes. However, conalbumin was able to produce a significant increase in the in vitro response of lymphocytes to PHA and PWM, suggesting an action on both T and B lymphocytes.
Adult↗
Steroid hormone regulation of ovalbumin and conalbumin gene transcription. A model based upon multiple regulatory sites and intermediary proteins.
Changes in rates of ovalbumin and conalbumin gene transcription and mRNA levels were monitored during an entire cycle of estrogen withdrawal and restimulation. Correlations of transcription rates with nuclear estrogen receptor levels in this experiment and in dose-response experiments reveal that conalbumin gene transcription is directly proportional to nuclear receptor levels, whereas ovalbumin gene transcription is related to receptor levels in a way that suggests cooperative interactions among receptors. Conalbumin mRNA accumulation and transcription are transiently inhibited by administration of progesterone to estrogen-stimulated chicks, whereas ovalbumin gene transcription is stimulated by this regimen. This puzzling observation can be rationalized if a single receptor binding site is involved in conalbumin gene regulation and multiple sites are involved in ovalbumin gene regulation. These ideas are combined with our recent observations that protein synthesis inhibitors and butyrate selectively, but reversibly, inhibit ovalbumin and conalbumin gene transcription. We describe a new hypothesis of how steroid hormones regulate egg white gene transcription in the chick oviduct.
Animals↗
Immobilization of conalbumin onto polystyrene/divinylbenzene co-polymers: towards finding the best support for MAMC.
Immediately after the successful immobilization of conalbumin onto CNBr-activated Sepharose, efforts were begun to find a less expensive support and a more benign chemistry of activation. The potential of the Sepharose-conalbumin conjugate for decontamination of several metal-containing waste-waters has been established, and a new method of chromatography has emerged, named metalloprotein affinity metal chromatography (MAMC). Efforts to immobilize conalbumin onto polystyrene/divinylbenzene co-polymers, using the well known and commercially available Merrifield, aminomethyl and plain polystyrene resins are presented here. Immobilizations of conalbumin were carried out on the Merrifield and Aminomethyl resins, but the procedures were time consuming and complicated by polymer aggregation. Because of high cost of these materials, research was directed towards the activation and functionalization of plain polystyrene/divinylbenzene co-polymers. Chlorosulfonation followed by sulfonamide formation was attempted on three commercially available polymers. Successful polysulfonamide formation was achieved with bislysine copper(II) acting as a diamine. Removal of the copper allows the unblocking of the alpha amino group of the immobilized lysine which in turn is treated with glutaraldehyde, affording an activated support for immobilization of proteins. To date, approximately 46 mg transferrin/g dry matrix have been successfully immobilized. The chemical and biological inertness of this support makes it a good candidate to scale up the procedure and continue the optimization of MAMC.
Chromatography, Affinity↗
Cell-specificity of the chicken ovalbumin and conalbumin promoters.
A series of recombinant plasmids containing increasing lengths of the 5'-flanking promoter sequences of the chicken conalbumin and ovalbumin genes fused to the sequences coding for the SV40 T-antigen have been constructed. These recombinants were introduced into a variety of established cell lines and primary cultured cells by nuclear microinjection. Promoter activity was estimated by monitoring T-antigen synthesis by indirect immunofluorescence. We show that the microinjected ovalbumin and conalbumin promoter regions do not function in chicken fibroblasts, kidney cells and in a variety of non-chicken cells, irrespective of the presence of steroid hormone receptors. In contrast, these promoter regions are active in primary cultured chicken embryonic hepatocytes and oviduct tubular gland cells, suggesting the presence of cell-specific transcription factors in these cells. Unexpectedly, promoter sequences close to the TATA boxes of both the ovalbumin and conalbumin genes are sufficient to confer cell-specific expression. Most of the controls exerted on the ovalbumin and conalbumin promoters in the whole animal appear to be reproduced in vitro by nuclear microinjection of the chimeric genes into the primary cultured cells. However, the microinjected ovalbumin promoter is active in embryonic hepatocytes and thus escapes the regulation imposed on the corresponding inactive endogenous gene.
Animals↗
Failure of rabbit reticulocytes to incorporate conalbumin or lactoferrin iron.
Despite the remarkable molecular similarity of human lactoferrin and human transferrin, the results of this investigation indicate that human lactoferrin was unable to furnish rabbit reticulocytes with iron for heme synthesis. Although conalbumin closely resembles transferrin in many of its properties, conalbumin iron-binding differs from human transferrin iron-binding. There are conflicting reports in the literature regarding conalbumin's ability to furnish iron to reticulocytes. In this study, small amounts of lactoferrin or conalbumin were adsorbed to mature and immature cell surfaces but neither of these iron-binding proteins surrendered iron intracellularly to reticulocytes for heme synthesis.
Animals↗
Effects of insulin-like growth factor-I, estrogen, glucocorticoid, and transferrin on the mRNA contents of ovalbumin and conalbumin in primary cultures of quail (Coturnix coturnix japonica) oviduct cells.
The effects of estrogen, dexamethasone, insulin-like growth factor-I (IGF-I), and transferrin on the messenger RNA (mRNA) contents of ovalbumin and conalbumin in primary cultures of quail oviduct cells were investigated. In the absence of one of the above hormones or factors, a decrease in ovalbumin mRNA was prominent. In particular, removal of IGF-I and transferrin caused a significant effect. Studies using a combination of estrogen, dexamethasone, IGF-I and transferrin indicated that IGF-I cooperates with estrogen or dexamethasone and transferrin works with dexamethasone. Specifically, IGF-I enhanced ovalbumin synthesis or increased cellular ovalbumin mRNA content depending on its concentration in the medium in the presence of estrogen. However, the effects of estrogen, dexamethasone, IGF-I, and transferrin were not similarly observed with conalbumin mRNA. These results show that ovalbumin synthesis is controlled by estrogen or glucocorticoid with IGF-I or transferrin and that cellular ovalbumin mRNA content is also regulated by these hormones or transferrin. In contrast, conalbumin synthesis and cellular content of conalbumin mRNA are not affected by these hormones under the conditions of the present study.
Animals↗