Ultrasensitive detection of intact SARS-CoV-2 particles in complex biofluids using microfluidic affinity capture.

Measuring virus in biofluids is complicated by confounding biomolecules coisolated with viral nucleic acids. To address this, we developed an affinity-based microfluidic device for specific capture of intact severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our approach used an engineered angiotensin-converting enzyme 2 to capture intact virus from plasma and other complex biofluids.

Amide proton hydrogen exchange rates for sperm whale myoglobin obtained from 15N-1H NMR spectra.

The hydrogen exchange behavior of exchangeable protons in proteins can provide important information for understanding the principles of protein structure and function. The positions and exchange rates of the slowly-exchanging amide protons in sperm whale myoglobin have been mapped using 15N-1H NMR spectroscopy. The slowest-exchanging amide protons are those that are hydrogen bonded in the longest helices, including members of the B, E, and H helices.

Solution structure of carbonmonoxy myoglobin determined from nuclear magnetic resonance distance and chemical shift constraints.

Solution NMR structures for sperm whale carbonmonoxy myoglobin have been calculated using 1301 distance restraints determined from nuclear Overhauser enhancement (NOE) measurements on 15N-labeled protein and chemical shift calculations for 385 protons. Starting structures included four crystal forms of myoglobin and 12 structures generated by metric matrix distance geometry. Refinements were also carried out using distance restraints alone.

1H and 15N resonance assignments and secondary structure of the carbon monoxide complex of sperm whale myoglobin.

Sequence-specific backbone 1H and 15N resonance assignments have been made for 95% of the amino acids in sperm whale myoglobin, complexed with carbon monoxide (MbCO). Many assignments for side-chain resonances have also been obtained. Assignments were made by analysis of an extensive series of homonuclear 2D spectra, measured with unlabeled protein, and both 2D and 3D 1H-15N-correlated spectra obtained from uniformly 15N-labeled myoglobin.

Backbone 1H, 13C, and 15N assignments and secondary structure of bovine low molecular weight phosphotyrosyl protein phosphatase.

Phosphotyrosyl protein phosphatases play an important role in mediating cellular signal transduction; yet three-dimensional structures of this important class of proteins have not been reported. We present the sequence-specific 1H, 13C, and 15N backbone assignments for the low molecular weight bovine heart phosphotyrosyl protein phosphatase (BHPTPase) (157 residues, 17,900). The assignments were obtained from a combination of double- and triple-resonance multidimensional NMR experiments.

Structural characterization of the FK506 binding protein unfolded in urea and guanidine hydrochloride.

Characterizing the structure properties of unfolded proteins is important for understanding the stability and folding of native proteins. However, little structural information is available for the unfolded state. Using recently developed heteronuclear multi-dimensional NMR techniques, the 1H, 13C and 15N chemical shift assignments of the FK506 binding protein (FKBP) unfolded in concentrated urea and guanidine hydrochloride (GuHCl) solutions have been obtained, and the structural properties of unfolded FKBP have been characterized.

Solution structure of the cyclosporin A/cyclophilin complex by NMR.

Cyclosporin A, a cyclic undecapeptide, is a potent immunosuppressant that binds to a peptidyl-prolyl cis-trans isomerase of 165 amino acids, cyclophilin. The cyclosporin A/cyclophilin complex inhibits the calcium- and calmodulin-dependent phosphatase, calcineurin, resulting in a failure to activate genes encoding interleukin-2 and other lymphokines. The three-dimensional structures of uncomplexed cyclophilin, a tetrapeptide/cyclophilin complex, and cyclosporin A when bound to cyclophilin have been reported.

Kinetics and mechanisms of reduction of Cu(II) and Fe(III) complexes by soybean leghemoglobin alpha.

The reduction of low-molecular-weight Cu(II) and Fe(III) complexes by soybean leghemoglobin alpha was characterized using both kinetic analysis and 1H-NMR experiments. Whereas Fe(III) (CN)6(3-) was reduced through an outer sphere transfer over the exposed heme edge, all other Cu(II) and Fe(III) complexes investigated were reduced via a site-specific binding of the metal to the protein. Reduction of all metal complexes was enhanced by decreasing pH while only Fe(III)NTA reduction kinetics were altered by changes in ionic strength.

Structural determination of the vasoactive intestinal peptide by two-dimensional H-NMR spectroscopy.

The structure of the vasoactive intestinal peptide 1-28 in 40% 2,2,2-trifluoroethanol was investigated by two-dimensional 1H-nmr spectroscopy. All 1H resonances, except the gamma, delta, and epsilon protons of the lysine residues, could be sequentially assigned. Numerous intraresidual as well as short-range interresidual nuclear Overhauser effect spectroscopy connectivities were observed.

NMR study of the interaction of beta-blockers with sonicated dimyristoylphosphatidylcholine liposomes in the presence of praseodymium cation.

The interaction of a series of beta-adrenoreceptor blocking agents with unilamellar dimyristoylphosphatidylcholine (DMPC) liposomes has been studied by proton nuclear magnetic resonance (1H-NMR) in the presence of praseodymium cation (Pr3+) at 30 degrees C. Addition of Pr3+ increased the splitting of the trimethylammonium group signals arising from the phospholipid molecules located at the internal and external surfaces of the bilayers. Adding Pr3+ caused a considerable downfield shift of the external peak but only a slight upfield shift of the internal peak (approximately 3%).

Biochemical characterization and osmolytes in papillary collecting ducts from pig and dog kidneys.

Papillary collecting duct tubules were prepared in gram quantities from the papillae of dog and pig kidneys. Measurements of substrate and oxygen utilizations by these tubules under both aerobic and anaerobic conditions showed the potential for both glycolysis and oxidative phosphorylation. Oxygen is not necessary to maintain a normal adenosine 5'-triphosphate concentration, but oxidative phosphorylation contributes to more than 65% of the metabolism under aerobic conditions in the two species.

Cardiovascular sutures as assessed by scanning electron microscopy.

Nine types of commercial sutures were investigated with respect to their suitability in cardiovascular surgery involving anastomosis of arterial prostheses. Polyester, nylon, silk and polypropylene in the form of multifilaments and monofilaments with or without coatings were included. The gross structure of the suture and the needle, the uniformity of the fibres and the coatings, the mechanical properties, before and after surgical use and the quality of the resulting anastomoses in canine models were evaluated.