Calorimetric and spectroscopic investigations of β-lactoglobulin upon interaction with copper ion

The effect of copper(II) ions (Cu(+2)) on the structure of β-lactoglobulin (β-lg) was investigated spectroscopically using UV-visible, fluorescence and circular dichroism (CD) and calorimetrically using isothermal titration calorimetry (ITC), at different temperatures. Results of the UV-visible studies showed that adding Cu(+2) to β-lg solution caused increasing turbidity, indicative of protein aggregation. It was noticeable that the rate of increasing turbidity was directly proportional to increasing temperature. The far-UV CD studies displayed that the Cu(+2) cannot induce any significant changes in the secondary structures of β-lg at different temperatures. Also, the ITC data indicated that the binding process of Cu(+2) to β-lg is mainly entropically driven. The results highlight that copper ions cause the tertiary structure of β-lg to change and induce a slightly open structure leading to the formation of supramolecular aggregates in β-lg which may result in the reduced allergenicity of β-lg and its increased use in industrial applications.     

Improving the functional properties of fish gelatin by conjugation with the water-soluble fraction of bitter almond gum

Food Science and Biotechnology - Maillard-based conjugation may be a useful way of improving the functional properties of food biopolymers. In this study, covalent attachment of fish gelatin (FG)...     

Photothermal nanoblade for large cargo delivery into mammalian cells

It is difficult to achieve controlled cutting of elastic, mechanically fragile, and rapidly resealing mammalian cell membranes. Here, we report a photothermal nanoblade that utilizes a metallic nanostructure to harvest short laser pulse energy and convert it into a highly localized explosive vapor bubble, which rapidly punctures a lightly contacting cell membrane via high-speed fluidic flows and induced transient shear stress. The cavitation bubble pattern is controlled by the metallic structure configuration and laser pulse duration and energy. Integration of the metallic nanostructure with a micropipet, the nanoblade generates a micrometer-sized membrane access port for delivering highly concentrated cargo (5 × 10(8) live bacteria/mL) with high efficiency (46%) and cell viability (>90%) into mammalian cells. Additional biologic and inanimate cargo over 3-orders of magnitude in size including DNA, RNA, 200 nm polystyrene beads, to 2 μm bacteria have also been delivered into multiple mammalian cell types. Overall, the photothermal nanoblade is a new approach for delivering difficult cargo into mammalian cells.     

Anti-GBM glomerulonephritis in mice lacking nitric oxide synthase type 2

To determine the relationship between quantitative Doppler parameters of portal, hepatic, and splanchnic circulation and hepatic venous pressure gradient (HVPG), variceal size, and Child-Pugh class in patients with alcoholic cirrhosis, we studied forty patients with proved alcoholic cirrhosis who underwent Doppler ultrasonography, hepatic vein catheterization, and esophagoscopy. The following Doppler parameters were recorded: time-averaged mean blood velocity, volume flow of the main portal vein flow, and resistance index (RI) of the hepatic and of the superior mesenteric artery. Doppler findings were compared with HVPG, presence and size of esophageal varices, and Child-Pugh class. There was a significant inverse correlation between portal velocity and HVPG (r = -.69), as well as between portal vein flow and HVPG (r = -.58). No correlation was found between RI in the hepatic artery or superior mesenteric artery and HVPG. No correlation was found between portal vein measurements and presence and size of varices. Severe liver failure was associated with lower portal velocity and flow. In patients with alcoholic cirrhosis, only portal vein blood velocity and flow, but neither hepatic nor mesenteric artery RI, are correlated to the severity of portal hypertension and to the severity of liver failure.     

New potentially antihypertensive peptides liberated in milk during fermentation with selected lactic acid bacteria and kombucha cultures

Compounds with the ability to inhibit angiotensin-converting enzyme (ACE) are used medically to treat human hypertension. The presence of such compounds naturally in food is potentially useful for treating the disease state. The goal of this study was to screen lactic acid bacteria, including species commonly used as dairy starter cultures, for the ability to produce new potent ACE-inhibiting peptides during milk fermentation. Strains of Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus helveticus, Lactobacillus paracasei, Lactococcus lactis, Leuconostoc mesenteroides, and Pediococcus acidilactici were tested in this study. Additionally, a symbiotic consortium of yeast and bacteria, used commercially to produce kombucha tea, was tested. Commercially sterile milk was inoculated with lactic acid bacteria strains and kombucha culture and incubated at 37°C for up to 72 h, and the liberation of ACE-inhibiting compounds during fermentation was monitored. Fermented milk was centrifuged and the supernatant (crude extract) was subjected to ultrafiltration using 3- and 10-kDa cut-off filters. Crude and ultrafiltered extracts were tested for ACE-inhibitory activity. The 10-kDa filtrate resulting from L. casei ATCC 7469 and kombucha culture fermentations (72 h) showed the highest ACE-inhibitory activity. Two-step purification of these filtrates was done using HPLC equipped with a reverse-phase column. Analysis of HPLC-purified fractions by liquid chromatography–mass spectrometry/mass spectrometry identified several new peptides with potent ACE-inhibitory activities. Some of these peptides were synthesized, and their ACE-inhibitory activities were confirmed. Use of organisms producing these unique peptides in food fermentations could contribute positively to human health.