Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0393754 (HSA)
 2,996 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HBsAg is known to bind to human serum albumin polymerized by glutaraldehyde, human serum albumin has been found in preparations of HBsAg by several investigators. However, it is not yet known whether natural human serum albumin binds to hepatitis B virus under physiological conditions. We studied the binding between natural or recombinant HBsAg and monomeric human serum albumin by immunological, biochemical and biophysical methods. The binding capacity of 20-nm HBs spheres was variable but ranged up to six molecules HSA/sphere. A reversible binding site for human serum albumin was exclusively localized in the preS2 domain, whereas the S domain was inactive in vitro. Human serum albumin copurified with HBsAg of human origin during gel chromatography or sucrose-gradient centrifugation. This human serum albumin was monomeric in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The preS2-bound part of the human serum albumin could be removed from HBsAg by high-salt, such as CsCl centrifugation, but another part could only be removed by treatment with a disulfide cleaving reagent. Most of this covalently bound human serum albumin was retained at the HBsAg particle after complete cleavage of medium-sized HBs protein with trypsin. This indicates a second way in which albumin binds irreversible to cysteine(s) of the small HBs protein (SHBs, P24 and GP27).
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PMID:Interaction between hepatitis B surface proteins and monomeric human serum albumin. 216 67

There are four polypeptides coded for by the region Pre-S and gene S on DNA of hepatitis B virus that carry the receptor for polymerized human serum albumin (poly-HSA), i.e., P31 and P39, as well as their glycosylated counterparts P35 and P43. With the use of monoclonal antibodies directed to Pre-S(1) sequence and Pre-S(2) sequence (bearing the receptor for poly-HSA), the content of these polypeptides, as well as their expression on the surface, was determined for hepatitis B particles of various categories. P39 and P43, carrying both Pre-S(1) and Pre-S(2) sequences, were contained abundantly in Dane and tubular particles, and to a much lesser extent in small spherical particles, all of which were purified from plasma containing hepatitis B e antigen (HBeAg). P31 and P35, carrying Pre-S(2) but not Pre-S(1) sequence, were contained comparably in these three categories of hepatitis B particles. In remarkable contrast, small spherical particles derived from plasma containing antibody to HBeAg were very low in the content of any Pre-S polypeptides. P31 and P39 showed higher activities for poly-HSA receptor than their glycosylated versions. When Dane particles were digested with trypsin, the poly-HSA receptor was deprived in parallel with the loss of antigenicity for Pre-S(2) sequence. The antigenicity for Pre-S(1) sequence was much less affected, and that for the product of gene S was virtually unchanged by the digestion.
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PMID:Polypeptides coded for by the region pre-S and gene S of hepatitis B virus DNA with the receptor for polymerized human serum albumin: expression on hepatitis B particles produced in the HBeAg or anti-HBe phase of hepatitis B virus infection. 300 21

In this study, the interaction of human serum low-density lipoprotein (LDL) with heparin immobilized on Sepharose was reinvestigated. Binding of isolated LDL (stabilized with human serum albumin (HSA] was compared with that of LDL in full serum. (1) Binding of isolated LDL was slightly decreased by CaCl2 and was not affected by MgCl2. In contrast, with full serum LDL binding was increased by these divalent cations. (2) In both situations, binding of LDL was saturable, but the maximum degree of binding that could be reached was much higher with isolated LDL than with LDL in full serum. This could be ascribed to an inhibitory action of a factor found in the d greater than 1.24 fraction of serum. (3) The effect of this factor was diminished in the presence of CaCl2 or MgCl2, which suggests that the stimulation of LDL binding by these cations in full serum is due to suppression of the inhibitory activity of this factor. (4) The inhibitory factor in the d greater than 1.24 fraction can be partially purified by absorption to heparin-Sepharose, followed by elution with 6 M guanidine chloride. The resulting preparation had a 30- to 50-fold higher specific activity. Attempts to purify the factor further resulted in loss of activity. (5) The activity is decreased upon treatment with trypsin and also upon acetylation or reduction with dithiothreitol, indicating that free amino groups and S-S bridges are essential.
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PMID:Binding of low-density lipoprotein to heparin-Sepharose: characterization and inhibition by serum high-molecular-weight components. 338 80

Human migration inhibitory factor (MIF), obtained from supernatants of peripheral blood mononuclear cells stimulated with concanavalin A, was analyzed by gel filtration, isoelectrofocusing, and CsCl density gradient centrifugation. A distinct pattern of heterogeneity was determined on the basis of its harvesting time and biochemical criteria. Supernatants from cells cultured for 1 day contained a single peak of MIF activity with an isoelectric point of 4.3 to 5.2, an apparent m.w. of 23,000, and a density of 1.314 g/ml, the same as the density of the marker protein, 125I-HSA (1st day pH 5-MIF). Furthermore, this species of human MIF was sensitive to treatment with trypsin, strongly suggesting its being a protein, but not to treatment with neuraminidase and corresponds therefore to guinea pig pH 5-MIF. However, when 2nd day supernatants were analyzed under the same conditions, 2 MIF species were found. One species with an isoelectric point of 2.4 to 3.3 had an apparent m.w. of 65,000 (2nd day 3-MIF). The other species with an isoelectric point of 4.3 to 5.6 had an apparent m.w. of 23-43,000 (2nd day pH 5-MIF). Upon centrifugation in CsCl density gradients, the density (rho 25 of 1.314 to 1.414 g/ml) of both species was found to be greater than that of the pure protein, 125I-HSA. In addition, both species were chymotrypsin and neuraminidase sensitive but not trypsin sensitive, further suggesting their glycoprotein nature.
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PMID:Studies on human migration inhibitory factor: characterization of three molecular species. 701 40

Human salivary and pancreatic alpha-amylases (HSA and HPA) are the respective gene products of the AMY1 and AMY2A genes. AMY2B is a newly found human alpha-amylase gene. The presence of the AMY2B gene product (HXA) in the urine of healthy humans was examined. A mixture of alpha-amylases that seemed to contain HXA, judging from the substrate specificity, was purified from urine of healthy volunteers by affinity adsorption on starch and then by ion-exchange chromatography. The mixture was reduced and S-alkylated, and the product was digested with trypsin. The digest was separated by reversed-phase HPLC. LVGLLDLALEKDYVR and LVGLLDLALEK, which were found in the digest, are peptides of HXA, but not of HSA and HPA. The detection of these characteristic peptides of HXA demonstrates the presence of HXA in the urine of healthy humans.
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PMID:Identification of the characteristic amino-acid sequence for human alpha-amylase encoded by the AMY2B gene. 826 4

Treatment of red cell ghosts with ozone inhibited both AChE (marking the outside of the membrane) and G3PDH (marking the inside of the membrane). There was no change in tryptophan fluorescence of the ghosts after the ozone treatment. Band 3 protein was isolated from the ozone-treated ghosts. The protein was digested with trypsin to obtain water soluble peptides from the cytoplasmic N-terminal tail and the interhelical loops. Fluorescent peptides included GWVIHPLGLR from the outer loop between helices 7 and 8, and peptide WMEAAR from the N-terminal cytoplasmic tail. Neither one of these peptides was oxidized by ozone. This was true whether or not the ghosts were sealed. We conclude that the position of these tryptophans either in the membrane structure, or because of binding to other proteins in the cytoplasmic tail, protects them from oxidation by ozone. Treatment of horse heart cytochrome c with ozone did not change the absorbance spectrum in the heme region or the tryptophan absorbing region. HPLC of the ozone-treated cytochrome c showed that cytochrome c was being modified, indicated by a change in the elution time. Treatment of cytochrome c with ozone did not change the activity in the NADH-cytochrome c reductase assay. Digestion of the ozone-treated cytochrome c with trypsin gave peptides which demonstrated normal fluorescence. (Cytochrome c has abnormally low fluorescence, which is not changed by ozone exposure.) The peptides were separated by HPLC. The fluorescence of the tryptophan-containing peptide (GITWK) was not decreased by treatment of the cytochrome c by ozone. Amino acid analysis of the ozone-treated cytochrome c indicated that methionine was oxidized. We conclude that tryptophan in cytochrome c is protected from oxidation by ozone because of the interaction with the porphyrin ring. Bovine serum albumin and human serum albumin were treated with ozone. There was a monotonic decrease in tryptophan fluorescence in both cases. Digestion of BSA with trypsin produced two fluorescent peptides. The peptide FWGK was identified by coelution with the authentic peptide. The putative peptide AWSVAR was not the same as the chemically synthesized peptide. The peptide sequences FWGK and "AWSVAR" were both oxidized in ozone-treated bovine serum albumin, with no detectable discrimination. Tryptic digestion of the ozone-treated human serum albumin produced a single fluorescent peptide, which was oxidized by ozone. The putative peptide AWAVAR in the tryptic digest of HSA was distinct from chemically synthesized peptide. The oxidation of tryptophans in proteins by ozone is markedly influenced by position in tertiary structure, position in membrane structure, and by chemical interactions within the protein.
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PMID:Reaction of ozone with protein tryptophans: band III, serum albumin, and cytochrome C. 902 65

Terminal sialic acids on cell surface glycoconjugates can carry 9-O-acetyl esters. For technical reasons, it has previously been difficult to determine their precise distribution on different cell types. Using a recombinant soluble form of the Influenza C virus hemagglutinin-esterase as a probe for 9-O-acetylated sialic acids, we demonstrate here their preferential expression on the CD4 T cell lineage in normal B10.A mouse lymphoid organs. Of total thymocytes, 8-10% carry 9-O-acetylation; the great majority of these are the more mature PNA-, HSA-, and TCRhi medullary cells. While low levels of 9-O-acetylation are seen on some CD4/CD8 double positive (DP) and CD8 single positive (SP) cells, high levels are present primarily on 80- 85% of CD4 SP cells. Correlation with CD4 and CD8 levels suggests that 9-O-acetylation appears as an early differentiation marker as cells mature from the DP to the CD4 SP phenotype. This high degree of 9-O-acetylation is also present on 90-95% of peripheral spleen and lymph node CD4 T cells. In contrast, only a small minority of CD8 T cells and B cells show such levels of 9-O-acetylation. Among mature peripheral CD4 T lymphocytes, the highly O-acetylated cells are Mel 14(hi), CD44(lo), and CD45R(exon B)hi, features typical of naive cells. Digestions with trypsin and O-sialoglycoprotease (OSGPase) and ELISA studies of lipid extracts indicate that the 9-O-acetylated sialic acids on peripheral CD4 T cells are predominantly on O-linked mucintype glycoproteins and to a lesser degree, on sialylated glycolipids (gangliosides). In contrast, sialic acids on mucin type molecules of CD8 T cells are not O-acetylated; instead these molecules mask the recognition of O-acetylated gangliosides that seem to be present at similar levels as on CD4 cells. The 9-O-acetylated gangliosides on mouse T cells are not bound by CD60 antibodies, which recognize O-acetylated gangliosides in human T cells. Tethering 9-O-acetylated mucins with the Influenza C probe with or without secondary cross-linking did not cause activation of CD4 T cells. However, activation by other stimuli including TCR ligation is associated with a substantial decrease in surface 9-O-acetylation, primarily in the mucin glycoprotein component. Thus, 9-O-acetylation of sialic acids on cell surface mucins is a novel marker on CD4 T cells that appears on maturation and is modulated downwards upon activation.
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PMID:9-O-Acetylation of sialomucins: a novel marker of murine CD4 T cells that is regulated during maturation and activation. 916 29

Two analytical systems based on the soluble and immobilized trypsin and conductometric thin-film electrodes were developed to measure concentration of artificial substrate and protein in solution. It was shown that these systems allow one to determine concentrations of Ha-benzoyl-L-arginin-ethyl-ester in the range of 0.1-1.0 mM and concentrations of HSA: 0.1-2.0 mg/ml with soluble and 0.1-0.8 mg/ml with immobilized trypsin.
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PMID:[Development of enzyme biosensor based on trypsin and conductometric thin-film electrodes for protein and artificial substrates determination]. 946 33

Surface-modified albumin nanoparticles were prepared from two poly(ethylene glycol)-human serum albumin conjugates: poly(thioetheramido acid)-poly(ethylene glycol) copolymer-grafted HSA (HSA-PTAAC-PEG) and methoxy poly(ethylene glycol)-grafted HSA (HSA-mPEG). Rose bengal (RB) was used as a model drug for encapsulation into the nanoparticles either during the particle production or by adsorption post particle preparation. The drug incorporation and release was affected by the different production methods and the different polymer compositions. When RB was loaded in HSA and HSA/HSA-PTAAC-PEG nanoparticles, up to 5% (w/w) drug content was achieved. The drug loading in HSA-mPEG nanoparticles was much lower and the results from the microcalorimetry study indicated that the low loading efficiency was due to less drug-protein binding sites available in the HSA-mPEG molecule as compared to the HSA molecule. The release of RB from the albumin nanoparticles was very slow in PBS and dramatically accelerated in the presence of trypsin. Compared with unmodified nanoparticles, the slower release of RB from the surface-modified HSA nanoparticles in the presence of the enzyme suggested that the existence of a steric hydrophilic barrier on the surface of the nanoparticles made digestion of the nanoparticles more difficult.
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PMID:Preparation and characterisation of rose Bengal-loaded surface-modified albumin nanoparticles. 1124 13

An extensive study was carried out on HSA and non-enzymatically glycated HSA by enzymatic digestion with trypsin and endoproteinase Lys-C, with the aim of identifying specific glycated peptides deriving from enzymatic digestion of glycated HSA. They may be considered, in pectore, as advanced glycation end products/peptides. These compounds, important at a systemic level in diabetic and nephropathic subjects, are produced by enzymatic digestion of in vivo glycated proteins: They are related to the pathological state of patients and have been invoked as responsible for tissue modifications. The digested mixtures obtained by the two enzymes were analyzed by MALDI/MS and LC/ESI/MSn, and clear cut differences were found. First of all, the digestion products of glycated HSA are generally less abundant than those observed in the case of unglycated HSA, accounting for the lower proclivity of the former to enzymatic digestion. MS/MS experiments on doubly charged ions, comparisons with a protein database, and molecular modeling to identify the lysine NH2 groups most exposed to glycation, identified some glycated peptides in digestion mixtures obtained from both types of enzymatic digestion. Residues 233K, 276K, 378K, 545K, and 525K seem to be privileged glycation sites, in agreement with the fractional solvent accessible surface values calculated by molecular modeling.
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PMID:Enzymatic digestion and mass spectrometry in the study of advanced glycation end products/peptides. 1504 55


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