Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antibody to native bovine nasal cartilage proteoglycan monomer was shown by enzyme-linked immunosorbent assay to react with the purified hyaluronic acid binding region of the monomer. Antibody was digested with pepsin to produce F(ab')2 and labeled with glutaraldehyde-activated ferritin. F(ab')2 and F(ab')2-ferritin were reduced and alkylated to render them monovalent (Fab'). Antibody Fab' binding to native proteoglycan monomer was studied by electron microscopy of monomer reacted with ferritin-labeled antibody Fab' spread in a cytochrome c film. Ferritin-labeled antibody Fab' bound primarily at one end of the proteoglycan monomer. This binding was partly inhibitable by unlabeled monovalent antibody Fab', demonstrating immunospecificity. The end of the monomer with bound ferritin sometimes appeared as the thin segment, previously observed to bind to hyaluronic acid. These observations indicate that the hyaluronic acid binding region is at only one end of each proteoglycan monomer and that ferritin-labeled antibody Fab' selectively attaches to this part of native proteoglycan monomers. This methodology should be useful for future structural studies of isolated proteoglycans.
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PMID:Immunoferritin binding to proteoglycan monomers. An electron microscopic study. 710 21

Antigens A and B, shown to be associated with the progestagen-dominated human endometrium, were partly purified and their properties studied. The antigens were recovered in the crude nuclei, the heavy particulate fraction and cytosol of decidua-rich tissue from early pregnancy. The antigens in cytosol were enriched by a combination of Concanavalin A-Sepharose chromatography and polyacrylamide gel electrophoresis. The immunological reactivity of the antigens after partial purification by Concanavalin A-Sepharose chromatography was retained after 30 min exposure to 4-85 degrees C at pH 7.4, or after 2 h to pH 2-12 at 22 degrees C. Trypsin, but not pepsin, RNase, DNase or neuraminidase, completely destroyed immunological reactivity of both antigens. The apparent molecular weight of both antigens determined by filtration on Sephadex G100 was 48 000. The isoelectric point of both antigens was approximately 4.9. The antigens were not immunologically related to transferrin, ceruloplasmin, alpha-1-antitrypsin, ferritin, uteroglobin, alpha-fetoprotein, human chorionic gonadotrophin, pregnancy-associated plasma proteins or pregnancy zone protein. Furthermore, the antisera to Antigens A and B did not react with the decidual cytosol of pregnant baboons or of pseudopregnant rats.
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PMID:Properties of the progestagen-dependent protein of the human endometrium. 743 Dec 86

Bovine lactoferrin binds to a 60 kDa heat shock protein of Helicobacter pylori. Binding ability was related to human immunoglobulin G because bovine lactoferrin binding proteins were isolated by extraction of cell surface associated proteins with distilled water, applied on IgG-Sepharose and nickel sulphate chelate affinity chromatography. Binding was demonstrated by Western blot after purified protein was digested with alpha-chymotrypsin and incubated with peroxidase-labeled bovine lactoferrin. Binding was inhibited by bovine lactoferrin, lactose, rhamnose, galactose, and two iron-containing proteins, ferritin and haptoglobin. Helicobacter pylori binds ferritin and haptoglobin via charge or hydrophobic interactions because this binding was not inhibited by specific and various glycoproteins or carbohydrates. Carbohydrate moieties of bovine lactoferrin molecules seem to be involved in binding because glycoproteins with similar carbohydrate structures strongly inhibited binding. Scatchard plot analysis of the binding of peroxidase-labeled bovine lactoferrin to H. pylori cells yielded a kd 2.88 x 10(-6) M. In addition, binding of H. pylori cells to bovine lactoferrin was enhanced when bacteria treated with pepsin or alpha-chymotrypsin after isolation from iron-restricted and iron-containing media.
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PMID:Cryptic domains of a 60 kDa heat shock protein of Helicobacter pylori bound to bovine lactoferrin. 911 43

Activation of covalently intact plasminogen by tissue-type plasminogen activator (tPA) is facilitated by a majority of proteins subjected to denaturing conditions. Except for heat-denatured apoferritin, the denatured proteins examined require partial proteolysis by plasmin for cofactor activity. The same proteins in their native state are resistant to proteolysis with plasmin and develop no activity. Denatured preparations of apoferritin, antithrombin, alpha1-protease inhibitor, alpha2-macroglobulin, and albumin also accelerate des(1-77)-plasminogen activation by tPA. The rate enhancements are comparable with that of the fibrin(ogen) fragments on a w/w basis. The cofactor activities are inhibited by 6-aminohexanoate and inactivated by pepsin. Analysis of heat-denatured apoferritin and albumin preparations by ultracentrifugation and gel chromatography indicates that cofactor is associated predominately with aggregates, which have binding capacity for both tPA and zymogen. Heat-denatured albumin pretreated with plasmin decreases K(M) and increases k(cat) for both intact plasminogen and des(1-77)-plasminogen activation by tPA, yielding catalytic efficiencies in excess of 8 x 10(3) M(-1) s(-1) and 2 x 10(4) M(-1) s(-1), respectively. Because of enhanced plasmin-catalyzed proteolysis of plasminogen to des(1-77)-plasminogen, activation by urokinase-type plasminogen activator is also facilitated by denatured proteins; activation of des(1-77)-plasminogen is not affected. It is concluded that denatured proteins serve as both cofactors and substrates in the fibrinolytic system, and that enhancement of plasminogen activation by denatured proteins is mechanistically indistinguishable from that observed with fibrin.
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PMID:Denatured proteins as cofactors for plasminogen activation. 926 48

In the goodeid placental analogue, trophotaeniae provide extraembryonic gut-derived exchange surfaces. Ameca splendens embryos possess endocytosing trophotaeniae that are capable of absorbing a dazzling array of proteinaceous substances. The iron core protein, native ferritin (NF), and several radioiodinated proteinaceous substances were used to study ligand and binding site pathways in the trophotaenial absorptive cells (TACs). Time sequence analysis of NF trafficking indicated an exclusively lysosomal pathway. Binding to TACs of NF was completely inhibitable by proteins containing multiple lysine residues such as apoferritin, bovine serum albumin (BSA), human transferrin (HTf), fetuin, hemoglobin, myoglobin, cytochrome c, ubiquitin, parvalbumin as well as the random copolymers, poly(Glu,Lys,Tyr)6:3:1 and poly(D-Glu,D-Lys)6:4. Peptide hormones and pepsin that contains only one lysine residue did not produce inhibitory effects. Radiolabels such as (125)I-BSA, (125)I-HTf and (125)I-poly(Glu,Lys,Tyr) bound to trophotaeniae in a specific saturable manner. Any two proteins were shown to hinder one another in getting hold of a binding site. Concentration-dependent (125)I-BSA binding and Scatchard analysis of the data revealed both low- and medium-affinity binding with apparent dissociation constants, K(d)s, of 3.4 x 10(-5) M and 2 x 10(-7) M, respectively. Binding of NF and radioiodinated proteins was inhibited in the presence of a large excess of L-Lys, D-Lys, and several dipeptides containing Lys. Both Ca(2+)-depletion and low pH dramatically reduced the TACs' capacity to bind proteins. The effects of acidotropic agents included a reversible loss of surface protein binding sites, tremendous vacuolation, and the arrest of lysosomal degradation. Collectively, present results demonstrate that TACs bind and absorb multiple proteinaceous substances through a mechanism satisfying the criteria of receptor-mediated endocytosis. It is concluded that scavenger protein binding sites are used to ingest proteins for lysosomal degradation, helping to meet the embryos' amino acid requirement.
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PMID:Scavenger receptors facilitate protein transport in the trophotaenial placenta of the goodeid fish, Ameca splendens (Teleostei: Atheriniformes). 1297 8

Spinach (Spinacia oleracea) cv Whitney was tested for iron bioavailabilty using an in vitro human intestinal cell culture ferritin bioassay technique previously developed. Spinach was cultured in a growth chamber for 33 days, harvested, and freeze-dried. Total iron in the samples was an average of 71 micrograms/g dry weight. Spinach was digested in vitro (pepsin and 0.1 M HCl followed by pancreatin and 0.1 M NaHCO3) with and without the addition of supplemental ascorbic acid. Caco-2 cell cultures were used to determine iron bioavailability from the spinach mixtures. Production of the iron-binding protein ferritin in the Caco-2 cells showed the supplemental ascorbic acid doubled bioavailability of iron from spinach. The data show fresh spinach is a poor source of iron, and emphasize the importance of evaluation of whole meals rather than single food items. The data support the usefulness of the in vitro/Caco-2 cell ferritin bioassay model for prescreening of space flight diets for bioavailable iron.
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PMID:Bioavailability of iron from spinach using an in vitro/human Caco-2 cell bioassay model. 1588 Sep 5

Samples of common and biofortified beans ( Phaseolus vulgaris ), both raw and cooked (autoclaved at 120 degrees C for 20 min) were analyzed for their polyphenol composition. Polyphenols were identified via HPLC-UV/diode array detection. Cooking favored the extraction of polyphenols without the need of a hydrolysis step, a fact that is of interest because this is the usual form in which beans are consumed. The main differences between white and colored beans were the presence of free kaempferol (13.5-29.9 microg g(-1)) and derivatives (kaempferol-3-O-glucoside) (12.5-167.5 microg g(-1)), only in red and black beans. An in vitro digestion (pepsin, pH2; pancreatin-bile extract, pH 7) was applied to beans to estimate bioaccessibility of individual polyphenols. Kaempferol from seed coats exhibited high bioaccessibility (45.4-62.1%) and a potent inhibitor effect on Fe uptake at concentrations ranging from 0.37 to 1.30 microM. Caco-2 cell ferritin formation was used to evaluate Fe uptake. Cell Fe uptake was significant only from white beans.
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PMID:Bioaccessibility of phenols in common beans ( Phaseolus vulgaris L.) and iron (Fe) availability to Caco-2 cells. 1898 54

The incidence of adhesion of Pasteuria penetrans endospores to Meloidogyne incognita second-stage juveniles (J2) was studied after pretreatment of the latter with monoclonal antibodies (MAb), cationized ferritin, and other organic molecules in replicated trials. Monoclonal antibodies developed to a cuticular epitope of M. incognita second-stage juveniles gave significant reductions in attachment of P. penetrans endospores to treated nematodes. MAb bound to the entire length of J2 except for the area of the lateral field, where binding was restricted to the incisures. Since reductions in attachment with MAb treatment were modest, it is uncertain if these results implicated a specific surface protein as a factor that interacted in binding of the endospore to the nematode cuticle. Endospore attachment was decreased following treatment of the nematode with the detergents sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB). Endospore attachment to live nematodes was significantly greater than attachment to dead nematodes. Attachment rates of three P. penetrans isolates to M. incognita race 3 varied between isolates. The effects of neuraminidase, pronase, pepsin, trypsin, lipase, and Na periodate on endospore attachment were inconsistent. The cationic dye alcian blue, which binds sulfate and carboxyl groups on acidic glycans, had no consistent effect on endospore attachment. The incidence of endospore attachment was significantly lower but modest, at best, for nematodes that were treated with cationized ferritin alone or cationized ferritin following monoclonal antibody. The lack of consistency or extreme reduction in most experiments suggests that attachment of P. penetrans spores to M. incognita is not specified by only one physico-chemical factor, but may involve a combination of at least two physico-chemical factors (including surface charge and movement of the J2). This points to a need for analysis of combined or factorial treatment effects.
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PMID:Effects of Monoclonal Antibodies, Cationized Ferritin, and Other Organic Molecules on Adhesion of Pasteuria penetrans Endospores to Meloidogyne incognita. 1927 93

Phytoferritin is a promising resource of non-heme iron supplementation, but it is not stable against degradation by proteases in the gastrointestinal tract. Therefore, how to improve the stability of ferritin in the presence of proteases is a challenge. Since (-)-epigallocatechin-3-gallate (EGCG) is rich in phenolic-hydroxyl groups, it could interact with ferritin through hydrogen bonds, thereby preventing protein from degradation. To confirm this idea, we focus on the interaction between EGCG and phytoferritin, and the consequence of such interaction. Results demonstrated that EGCG did interact with ferritin, and such interaction induced the change in the tertiary/quaternary structure of protein but not in its secondary structure. Furthermore, stopped-flow and dynamic light scattering (DLS) results showed that EGCG could trigger ferritin association. Consequently, such protein association markedly inhibited protein digestion by pepsin at pH 4.0 and by trypsin at pH 7.5. These findings raise the possibility to improve the stability of phytoferritin in the presence of proteases.
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PMID:Phytoferritin association induced by EGCG inhibits protein degradation by proteases. 2538 42

There are many components with different properties co-existing in food, so interactions among these components are likely to occur, thereby affecting food quality. However, relatively little information is available on such interactions. In this study, we focus on the interaction between tannic acid (TA) and soybean seed ferritin (SSF), since they co-exist in many foodstuffs, and the consequence of this interaction. As expected, TA interacts with SSF, resulting in changes in the tertiary/quaternary structure of the protein, while having no effect on its primary and secondary structure. On one hand, such interaction leads to protein association, which markedly inhibited ferritin degradation by pepsin at pH 4.0 and trypsin at pH 7.5. On the other hand, iron release was faster with TA than with ascorbic acid, and such release has a negative effect on iron supplementation. These results help to understand the interactions of food components.
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PMID:Effect of tannic acid on properties of soybean (Glycine max) seed ferritin: a model for interaction between naturally-occurring components in foodstuffs. 2568 13


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