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Tryptophan is an essential amino acid deficient in cereals, especially maize. However, maize (Zea mays L.) is the main source of protein in some developing countries in Africa and Latin America. In general, the nutritional profile of cereals is poor, because they are deficient in essential amino acids such as tryptophan and lysine due to a relatively higher proportion of alcohol-soluble proteins. Quality protein maize (QPM) has been developed through genetic manipulation for the nutritional enrichment of maize to address these problems. Nevertheless, methods for protein, lysine and tryptophan are time-consuming and require relatively large amounts of samples. Therefore, we have advanced here a simple, cheap, fast, reliable and robust procedure for the determination of protein and tryptophan in the same biuret supernatant, which can also be used for chemical characterization of other cereals. Samples of 50 mg maize ground to pass through a 0.1 mm screen were sonicated for 5 min. in eppendorf vials with 1.5 mL of a biuret reagent each. After centrifugation and protein determination by biuret, 0.2 mL of supernatant was treated with 0.8 mL of a tryptophan reagent. Both total protein and tryptophan can be determined in microplates at 560 nm to speed up the measurements. The main advantage of the new micro-method is the rapid estimation of the nutrient quality of maize samples by a single weighing of a small amount of valuable plant materials. [ABSTRACT FROM AUTHOR]

Bacteriorhodopsin (BRh), which is present in the cell membranes of the archaeon Halobacterium salinarum, harvests light wave energy which causes conformational changes in this retinal protein leading to the release of adenosine triphosphate (ATP) by ATP synthase. Since some protons are released during light-induced excitation of BRh molecules, the chemiosmotic hypothesis advanced by Peter Mitchell was used to explain the ATP formation by translocation of protons across the simple membranes of H. salinarum. However, protons can be released as a result of photoexcitation of some molecules, and these protons are only responsible for increasing the acidity (pKa) of their solutions; therefore, the protons released by BRh probably have no role in ATP production. In contrast, the 138 nm spectral shift between the two photointermediates, L550 and M412, corresponds to an energy amount of 17.41 kcal/mole, which can be successfully absorbed by ATP synthase as near-infrared radiation (NIR). The conformational changes of F0 ATP-synthase can induce the rotation of F1 ATP-synthase, which is associated with the removal of ATP molecules already formed by F1 ATP-synthase from ADP and inorganic phosphate. The NIR radiant energy can thus be confusingly associated with proton release and not with direct light-induced ATP formation. The already proposed mechanism of ATP production by BRh-ATP-synthase system is supported by a large body of literature data. However, such data that contradict old theories can be interpreted in the light of new understandings of living organisms. Therefore, a new perspective on ATP production in biological systems from the simplest to higher organisms is required. [ABSTRACT FROM AUTHOR]

The utilization of spectrophotometric methods for the determination and analysis of proteins is of great interest as they are generally simple, rapid and with high sensitivity. These protein assays have many uses in the food, plant breeding, pharmaceutical and biomedical industries, as well as in forensic science and a variety of other research fields. Among these, the biuret method is highly sensitive and is widely used in clinical and biological laboratories. However, the use of copper sulphate in the traditional biuret method of protein identification can lead to substantial interference from copper ions. In this framework, we modified the traditional biuret method by using an alkaline-alcohol reagent and insoluble copper phosphate; the protein-copper complex could also be evaluated at 545 nm. In addition, aliquots of the same solution are treated with specific reagents to determine two essential amino acids; tryptophan reacts with glyoxylic acid and lysine is treated with a ninhydrin-based reagent. Calibration curves must also be made at three wavelengths, with absorbance values in relation to the concentration of each component measured by standard methods. The advantage of this new approach is that it requires only 50 mg of ground seed meal to quantify three different components in each sample. [ABSTRACT FROM AUTHOR]

Oncogenes are thought to play an important role in aberrant regulation of growth factors, which is believed to be an initiation event of carcinogenesis. However, recent genetic and pharmacological studies have shown that the Warburg effect (WE) is needed for tumour growth. It refers to extensively studied aerobic glycolysis over the past decade, although its impact on cancer remains unclear. Meanwhile, a large body of evidence has indicated that oxidative stress (OS) is connected with the occurrence and progression of various forms of cancer. Psychosocial factors (PSF), such as chronic depression, sadness, stressful life experiences, stress-prone personality, and emotional distress or poor quality of life affect the immune system and contribute to cancer outcomes. Here, we examine the relationship between WE, OS, PSF, metal ions, other carcinogens, and the development of different cancers from the viewpoint of physiological and biochemical mechanisms. [ABSTRACT FROM AUTHOR]

This study identifies a source of heavy metal pollution in the Tarnița-Ostra area, Suceava County, Romania, using both chemical and biological techniques. Samples collected from the sterile dumps and the surrounding soil were digested and analyzed for total metals and arsenic by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and atomic absorption spectrometry (AAS). High concentrations of heavy metals, such as copper (3.12 g/kg), arsenic (0.68 g/kg), lead (2.67 g/kg), zinc (0.43 g/kg) and barium (0.54 g/kg), found in that region, may pose a high risk to the environment and public health through the food chain. The large amounts of Cu, Fe, Pb, Zn and As of the collected samples diminished much the germination of wheat (Triticum aestivum L.), used in this study as a marker of toxicity. However, after the removal of the heavy metals by treating the aqueous extracts with sodium hydroxide solutions, the germination parameters returned to normal. The quantification of heavy metal levels by ICP-OES provides a better understanding of the potential ecological risks and contamination status of the tailings dumps. Instead, wheat germination tests can be reliable and inexpensive biological methods to prove the harmful effect of heavy metals and arsenic on plants. [ABSTRACT FROM AUTHOR]

Peptide-based hydrogels have become an area of intense investigation due to their easy design, possibility to make a large range of hierarchical nanostructures and their high biocompatibility and biodegradability. Here, we investigated by mass spectrometry (MS) a few synthetic gel-forming peptides having different amino acid sequences. Four different peptides were selected for MS measurements: EEEOH, FFFFF-OH, FESNF-NH2, and LWMRFA-OH. Our data show that mass spectrometry can be used to get detailed information on structure, molecular weight, and chemical bond energies of gel-forming peptides as well as to assess their purity and stability. Fourier transform infrared spectroscopy (FTIR) and theoretical studies carried out using GPMAW and ChemDraw Ultra computer programs confirmed the MS data. The peptide tendency to aggregate, a process observed by MS in the case of peptide EEE in a polar environment, was also theoretically investigated by molecular modeling. [ABSTRACT FROM AUTHOR]