Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:002116 (ACS)
 78,058 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Enzymes subjected to freeze-thawing are known to be protected by polymers that are preferentially excluded from the hydrated surface of proteins [reviewed in Carpenter et al. (1994) ACS Symp. Ser. 567, 134-147]. Preferentially excluded solutes are also known to stabilize quaternary structure, which enhances the thermostability of multimeric proteins in aqueous systems. Also, it has been suggested that retention of quaternary structure may play a role in the protection of multimeric proteins by polymers during freeze-drying (lyophilization). Although preferential solute exclusion cannot occur in the absence of water, we reasoned that polymers could protect multimeric proteins during freeze-drying by stabilizing quaternary structure in the frozen state. Our results are consistent with this hypothesis and demonstrate that bovine serum albumin and polyvinylpyrrolidone stabilize lactate dehydrogenase by inhibiting dissociation in the frozen solution, during the initial phase of the sublimation step of lyophilization. Dissociation at this critical step correlated directly with decreased recovery of enzyme activity after rehydration. The damage to the protein, under conditions where dissociation was studied, was due to a large decrease in pH in the frozen state (e.g., from pH 7.5 to 4.5), which was attenuated by protective levels of polymers. Thus, inhibition of freezing-induced pH shifts, in addition to stabilization by the preferential exclusion mechanism, plays an important role in the protection conferred by polymers. Furthermore, high concentrations of these polymers were capable of maintaining quaternary structure during subsequent drying and rehydration. We suggest that the proximate cause for increased recovery of active, native protein after lyophilization is that the holoenzyme is more resistant to the stresses of drying/rehydration than unassociated monomers.
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PMID:Polymers protect lactate dehydrogenase during freeze-drying by inhibiting dissociation in the frozen state. 880 30

Asian medicines are widely used as alternative medicine. However, interactions between drugs and Asian medicines have been poorly studied. Chan Su and Lu-Shen-Wan are Asian medicines that contain the cardiaoactive compound bufalin. Bufalin is structurally similar to digitoxin and is also strongly bound to serum albumin. The authors studied possible displacement of digitoxin from the protein binding site by bufalin. The authors prepared three serum pools from patients taking digitoxin and supplemented aliquots of each serum pool with no bufalin (control) and 25 ng/mL, 50 ng/mL, 100 ng/mL, 250 ng/mL, 500 ng/mL, and 1000 ng/mL bufalin. The authors observed significant displacement of digitoxin by bufalin as evidenced by increased free digitoxin concentrations. For example, the concentration of free digitoxin increased from a control value of 1.6 ng/mL to 2.5 ng/mL in the presence of 1000 ng/mL bufalin (total digitoxin: 36.3 ng/mL) in the serum pool 1. The authors observed similar increases in free digitoxin concentrations in other serum pools in the presence of various concentrations of bufalin. The authors used a chemiluminescent assay and ACS:180 analyzer to measure both total (in the original serum) and free (in the protein-free ultrafiltrate) digitoxin concentrations because the chemiluminescent assay does not cross-react with bufalin. When an acetone/water (1:1 by volume) extract of Chan Su was added to a serum pool containing digitoxin, the authors observed a significantly increased free digitoxin concentration, indicating that Chan Su can displace digitoxin from the protein binding site in vitro. The authors conclude that bufalin and acetone/water extract of Chan Su can cause significant displacement of digitoxin from the protein binding site.
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PMID:Interactions between drugs and Asian medicine: displacement of digitoxin from protein binding site by bufalin, the constituent of Chinese medicines Chan Su and Lu-Shen-Wan. 1077 25

Nature has evolved proteins and enzymes to carry out a wide range of sophisticated tasks. Proteins modified with functional polymers possess many desirable physical and chemical properties and have applications in nanobiotechnology. Here we describe multivalent Newkome-type polyamine dendrons that function as synthetic DNA binding domains, which can be conjugated with proteins. These polyamine dendrons employ naturally occurring spermine surface groups to bind DNA with high affinity and are attached onto protein surfaces in a site-specific manner to yield well-defined one-to-one protein-polymer conjugates, where the number of dendrons and their attachment site on the protein surface are precisely known. This precise structure is achieved by using N-maleimido-core dendrons that selectively react via 1,4-conjugate addition with a single free thiol group on the protein surface--either Cys-34 of bovine serum albumin (BSA) or a genetically engineered cysteine mutant of Class II hydrophobin (HFBI). This reaction can be conducted in mild aqueous solutions (pH 7.2-7.4) and at ambient temperature, resulting in BSA- and HFBI-dendron conjugates. The protein-dendron conjugates constitute a specific biosynthetic diblock copolymer and bind DNA with high affinity, as shown by ethidium bromide displacement assay. Importantly, even the low-molecular-weight first-generation polyamine dendron (1 kDa) can bind a large BSA protein (66.4 kDa) to DNA with relatively good affinity. Preliminary gene transfection, cytotoxicity, and self-assembly studies establish the relevance of this methodology for in vitro applications, such as gene therapy and surface patterning. These results encourage further developments in protein-dendron block copolymer-like conjugates and will allow the advance of functional biomimetic nanoscale materials.
ACS Nano 2007 Sep
PMID:Precisely defined protein-polymer conjugates: construction of synthetic DNA binding domains on proteins by using multivalent dendrons. 1920 26

We show that light-assisted oxidation with hydrogen peroxide effectively and rapidly opens holes in carbon nanohorn walls and, more importantly, creates abundant oxygenated groups such as carboxylic groups at the hole edges. These oxygenated groups reacted with the protein bovine serum albumin. The obtained conjugates were highly dispersed in phosphate-buffered saline and were taken up by cultured mammalian cells via an endocytosis pathway.
ACS Nano 2007 Nov
PMID:Light-assisted oxidation of single-wall carbon nanohorns for abundant creation of oxygenated groups that enable chemical modifications with proteins to enhance biocompatibility. 1920 76

Metallic nanoparticles influence the quantum yield and lifetime of adjacent fluorophores in a manner dependent on the properties of the nanostructure. Here we directly compare the fluorescence enhancement of the near-infrared fluorophore IR800 by Au nanoshells (NSs) and Au nanorods (NRs), where human serum albumin (HSA) serves as a spacer layer between the nanoparticle and the fluorophore. Our measurements reveal that the quantum yield of IR800 is enhanced from approximately 7% as an isolated fluorophore to 86% in a NSs-HSA-IR800 complex and 74% in a NRs-HSA-IR800 complex. This dramatic increase in fluorescence shows tremendous potential for contrast enhancement in fluorescence-based bioimaging.
ACS Nano 2009 Mar 24
PMID:Fluorescence enhancement by Au nanostructures: nanoshells and nanorods. 1923 23

Antibody mimic proteins (AMPs) are polypeptides that bind to their target analytes with high affinity and specificity, just like conventional antibodies, but are much smaller in size (2-5 nm, less than 10 kDa). In this report, we describe the first application of AMP in the field of nanobiosensors. In(2)O(3) nanowire based biosensors have been configured with an AMP (Fibronectin, Fn) to detect nucleocapsid (N) protein, a biomarker for severe acute respiratory syndrome (SARS). Using these devices, N protein was detected at subnanomolar concentration in the presence of 44 microM bovine serum albumin as a background. Furthermore, the binding constant of the AMP to Fn was determined from the concentration dependence of the response of our biosensors.
ACS Nano 2009 May 26
PMID:Label-free, electrical detection of the SARS virus N-protein with nanowire biosensors utilizing antibody mimics as capture probes. 1942 93

Amyloids are a family of self-aggregating proteins implicated in various central nervous system disorders, including Alzheimer's disease (AD). It is thought that prefibrillar soluble forms of amyloid peptides, including oligomers, may be the main pathogenic factor in AD. Herein we describe the fabrication of well-defined, functionalized, monomeric beta-amyloid peptide surfaces for studying protein-protein interactions. We first prepared a nonaggregating analogue of the beta-amyloid peptide and then attached it to a gold surface covered with a self-assembled monolayer (SAM) of alkanethiols. After attachment, the native form of the beta-amyloid peptide (Abeta40) was obtained by surface-level intramolecular O-N migration. The surface was characterized by atomic force microscopy (AFM) and self-assembled monolayer for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (SAMDI-TOF MS). The interaction between the surface-bound Abeta40 and monoclonal anti-Abeta40 antibody was tracked by AFM and chemiluminescence, which revealed that the Abeta40 was attached mainly in its monomeric form and that the protein-protein complex was assembled on the surface. Last, we used a proteomics approach to demonstrate the specificity of the Abeta40-functionalized surface in surface-binding experiments employing serum amyloid P (SAP) and bovine serum albumin (BSA).
ACS Nano 2009 Oct 27
PMID:An intramolecular O-N migration reaction on gold surfaces: toward the preparation of well-defined amyloid surfaces. 1977 98

Caveolae are plasma membrane invaginations prominent in all endothelial cells lining blood vessels. Caveolae characteristically bud to form free cytoplasmic vesicles capable of transporting carrier proteins such as albumin through the cell. However, caveolae size distribution and dynamics in living endothelial cells and ability of caveolae to internalize nanoparticles are not well understood. We demonstrate here the design of a dual-color nanoparticle pair to measure noninvasively caveolae size and dynamics. First, we coated nanoparticles with BSA (bovine serum albumin) to address whether albumin promoted their delivery. Albumin has been shown to bind to protein on endothelial cell surface localized in caveolae and activate albumin endocytosis. Imaging of BSA-coated nanoparticles varying from 20 to 100 nm in diameter in endothelial cells demonstrated that caveolae-mediated nanoparticle uptake was dependent on albumin coating of particles. We also showed that caveolae could accommodate up to 100 nm diameter nanoparticles, a size larger than the diameter of typical caveolae, suggesting compliant property of caveolae. Together, our results show the feasibility of tracking multicolored nanoparticles in living endothelial cells and potential usefulness for designing therapeutic nanoparticle cargo to cross the limiting vessel wall endothelial barrier.
ACS Nano 2009 Dec 22
PMID:Size and dynamics of caveolae studied using nanoparticles in living endothelial cells. 1991 48

We describe molecular capturing properties of protein nanotubes with a controllable ligand binding affinity and size selectivity. These practical biocylinders were prepared using an alternating layer-by-layer (LbL) assembly of protein and oppositely charged poly(amino acid) into the nanoporous polycarbonate (PC) membrane (pore diameter, 400 nm), with subsequent dissolution of the template. The tube wall typically comprises six layers of poly-L-arginine (PLA) and human serum albumin (HSA) [(PLA/HSA)(3)]. Use of high molecular weight PLA (M(w) = ca. 70 000) yielded robust nanotubes, which are available as lyophilized powder. The (PLA/HSA)(3) nanotubes swelled considerably in water, although the outer diameter was almost unaltered. Uranyl ion, 3,3'-diethylthiacarbocyanine iodide, and zinc(II) protoporphyrin IX (ZnPP) were bound to the HSA component in the cylinder wall. Similar nanotubes comprising recombinant HSA mutant [rHSA(His)], which has a strong binding affinity for ZnPP, captured this ligand more tightly. Furthermore, addition of excess myristic acid released ZnPP from the tubes through a ligand replacement reaction. The hybrid nanotubes bearing a single avidin layer as an internal surface captured FITC-biotin efficiently. Biotin-labeled nanoparticles are also incorporated into the tubes when their particle size is sufficiently small to enter the pores. Subsequent TEM observation revealed a line of loaded nanoparticles (100 nm) in the one-dimensional space interior.
ACS Nano 2010 Jan 26
PMID:Molecular capture in protein nanotubes. 2002 Jul 54

A design of smart surfaces responsive to biochemical analytes is demonstrated in the example of mixed monolayers of biotin/fluorocarbon. The contact angle of aqueous solutions on such surfaces decreases upon streptavidin binding and can be used in detecting this protein. The specificity of the effect is confirmed by the lack of a contact angle change by streptavidin blocked with biotin and by bovine serum albumin.
ACS Appl Mater Interfaces 2009 Apr
PMID:Biochemically responsive smart surface. 2016 97


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