muramidase and lauric-acid

In this study, a simple, rapid, and label-free sensor was developed for detecting the enzymatic activity of catalase (CAT) with liquid crystals (LCs) confined in microcapillaries. Inside a microcapillary functionalized with n-octyltrichlorosilane, aldehyde-doped LCs anchored radially so that a pattern of straight lines was observed under a polarized optical microscope (POM). However, once hydrogen peroxide (HP) oxidized the aldehyde into carboxylic acid, which has surface activity, the orientation of the LCs at the interface changed, resulting in a distinct pattern change, from straight to crossed. In this system, the enzymatic activity of CAT could be detected as it inhibits the oxidation by decomposing HP; as a result, the pattern changed back to the straight one. From the orientational and optical shift, the enzymatic activity of CAT was detected up to a concentration of 0.8 fM under mild experimental conditions and 8 aM at pH 9.0. This result suggests the need for further study of microcapillary systems to develop simple and sensitive sensors for biochemical interactions.

Topics: Aldehydes; Biosensing Techniques; Capillary Tubing; Catalase; Hydrogen Peroxide; Lauric Acids; Liquid Crystals; Microscopy, Polarization; Muramidase; Trypsin; Urease

We investigate the influence of three volatile alkylammonium acetate buffers on binding affinities for protein-ligand interactions determined by native electrospray ionization-mass spectrometry (ESI-MS). Four different types of proteins were chosen for this study. A charge-reduction effect was observed for all the cases studied, in comparison to the ions formed in ammonium acetate solution. When increasing the collision energy, the complexes of trypsin and the ligand were found to be more stable when sprayed from alkylammonium acetate buffers than from ammonium acetate. The determined dissociation constant (K

Topics: Acetates; Buffers; Carbonic Anhydrase II; Chlorothiazide; Lactoglobulins; Lauric Acids; Ligands; Muramidase; Proteins; Spectrometry, Mass, Electrospray Ionization; Sulfones; Trypsin

To develop edible films having controlled release properties for multiple bioactive compounds, hydrophobicity and morphology of zein films were modified by blending zein with oleic (C18:1)Δ⁹, linoleic (C18:2)Δ(9,12), or lauric (C₁₂) acids in the presence of lecithin. The blend zein films showed 2-8.5- and 1.6-2.9-fold lower initial release rates for the model active compounds, lysozyme (LYS) and (+)-catechin (CAT), than the zein control films, respectively. The change of fatty acid chain length affected both CAT and LYS release rates while the change of fatty acid double bond number affected only the CAT release rate. The film morphologies suggested that the blend films owe their controlled release properties mainly to the microspheres formed within their matrix and encapsulation of active compounds. The blend films showed antilisterial activity and antioxidant activity up to 81 μmol Trolox/cm². The controlled release of multiple bioactive compounds from a single film showed the possibility of combining application of active and bioactive packaging technologies and improving not only safety and quality but also health benefits of packed food.

Topics: Anti-Bacterial Agents; Antioxidants; Catechin; Dietary Proteins; Disk Diffusion Antimicrobial Tests; Fatty Acids, Nonesterified; Food Packaging; Food Preservation; Hydrophobic and Hydrophilic Interactions; Lauric Acids; Lecithins; Linoleic Acid; Listeria; Microbial Viability; Microspheres; Muramidase; Oleic Acid; Solubility; Surface Properties; Zein

To investigate the dynamic effect of tear lipocalins (TLs), the major lipid-binding protein in tears, at aqueous-cornea and lipid-aqueous interfaces, and their potential contribution to surface tension in the tear film.. Human apo- and holo-TLs were applied to the aqueous subphase in a Langmuir trough, and changes in surface pressure were measured. Changes in the contact angle of tear components were observed on Teflon and ferric-stearate-treated surfaces. A nitroxide-labeled derivative of lauric acid and a fluorescence-labeled derivative of palmitic acid were used to monitor the dynamic interaction of lipid removed from a hydrophobic surface by the major tear components in solution.. TLs increase the surface pressure at the aqueous-air interface by penetrating, spreading, and rearranging on the surface. Apo-TLs show a longer diffusion-dependent induction time than holo-TLs due to more extensive oligomerization of the apoprotein. Kinetic analysis of relaxation time suggests that apo-TLs have more rapid surface penetration and rearrangement than holo-TLs, indicative of a more flexible structure in apo-TLs. TLs reduce the contact angle of solutions on lipid films, a property that is greater with TLs than other tear proteins. TLs, unlike lysozyme and lactoferrin, remove labeled lipids from hydrophobic surfaces and deliver them into solution.. TLs are potent lipid-binding proteins that increase the surface pressure of aqueous solutions while scavenging lipids from hydrophobic surfaces and delivering them to the aqueous phase of tears. These data suggest important functional roles for TLs in maintaining the integrity of the tear film.

Topics: Carrier Proteins; Chromatography, Gel; Cornea; Cysteine Proteinase Inhibitors; Electron Spin Resonance Spectroscopy; Electrophoresis, Polyacrylamide Gel; Humans; Lactoferrin; Lauric Acids; Lipocalin 1; Muramidase; Palmitic Acids; Tears