Molecular docking of the pentapeptide derived from rice bran protein as anticancer agent inhibiting both receptor and non-receptor tyrosine kinases.

The cationic pentapeptide Glu-Gln-Arg-Pro-Arg (EQRPR) belongs to the family of anti-cancer peptides with significant anti-cancer activity. However, the mechanism by which the peptide performs this activity is unknown. In this study, we explored the pharmaceutical profile of Glu-Gln-Arg-Pro-Arg pentapeptide and revealed its anticancer properties by in silico docking studies. Moreover, the effect of EQRPR behavior of the DPPC membrane was investigated by means of Langmuir monolayer technique and the results were discussed in terms of mutual interactions. To evaluate the binding mechanisms, the pentapeptide and its various D-amino acid substituted analogs were docked to both epidermal growth factor receptor (EGFR) tyrosine kinase and proto-oncogene tyrosine-protein kinase, Fyn. Simultaneous binding of the pentapeptides to both EGFR and Fyn proteins, which are receptor- and non-receptor-kinases, respectively, suggest that these peptides can be an effective agent for cancer treatment. Moreover, to show the potential of the investigated pentapeptides to overcome the generated mutation-related drug resistance to EGFR targeted therapies, molecular docking investigations of EQRPR and all its D-analogs were performed against the prospective targets: Wild type EGFRWT and mutant EGFRT790M. Erlotinib and TAK-285 were used as reference molecules. The strong interaction of the peptide with EGFRWT (from -9.24 to -9.75 kcal/mol) and the secondary mutant EGFRT790M (from -9.28 to -9.64 kcal/mol) observed in most cancer recurrence cases indicates its good potential to overcome drug resistance in cancer therapy. In addition, the pharmacological properties of the investigated pentapeptides were revealed by in silico ADME (Absorption, Distribution, Metabolism, Excretion) and toxicity analysis.Communicated by Ramaswamy H. Sarma.

Membrane Partitioning of TEMPO Discriminates Human Lung Cancer from Neighboring Normal Cells.

The plasma membranes of normal and cancer cells of the lung, breast, and colon tissues show considerably different lipid compositions that greatly influence their physicochemical properties. Partitioning of the spin probe 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) into the membranes of human lung normal and carcinoma cells was assessed by EPR spectroscopy to estimate the impact of the lipid compositions. The goal was to reveal potential strategies for cancer therapy attributable to the membrane properties. The study was conducted at pH values of 7.3 and 6.2, relevant to the microenvironments of normal and cancer cells, respectively. The TEMPO partitioning was examined in the temperature interval of 283-317K to reveal the efficacy of local hyperthermia used in chemotherapy. Results indicate that the TEMPO partitioning coefficient for the membranes of human lung carcinoma cells is significantly higher compared with that of neighboring normal cells. Increased partition coefficients were observed at relatively higher temperatures in both normal and cancer cells. However, compared to the normal cells, the cancer cells demonstrated higher partition coefficients in the studied temperature range. The data obtained with C12SL (spin-labeled analog of lauric acid) indicate that increased membrane dynamics of the cancer cells is a possible mechanism for enhanced partitioning of TEMPO. Free energy values for partitioning estimated for pH values of 6.2 and 7.3 show that TEMPO partitioning requires 30% less energy in the cancer cells at pH 7.3. TEMPO and its derivatives have previously been considered as theranostic agents in cancer research. Data suggest that TEMPO derivatives could be used to test if complementary alkalization therapy is effective for cancer patients receiving standard chemotherapy with local hyperthermia.

Drought-induced changes in photosynthetic membranes of two wheat (Triticum aestivum L.) cultivars.

Two wheat (Triticum aestivum L.) cultivars contrasting in architectonics and differing in drought resistance, Azamatli-95 (short stature, vertically oriented small leaves, drought-tolerant) and Giymatli-2/17 (short stature, broad and drooping leaves, drought-sensitive), were studied. It was found that the content of CP I (115 kDa) and 63-kDa apoprotein P700 and also LHC II polypeptides increases slightly in the drought-resistant cv. Azamatli-95 under extreme water supply limitation, while their content decreases in drought-sensitive cv. Giymatli-2/17. The intensity of synthesis of alpha- and beta-subunits of CF(1) (55 and 53.5 kDa) and 33-30.5 kDa proteins also decreases in the sensitive genotype. The intensity of short wavelength peaks at 687 and 695 nm sharply increases in the fluorescence spectra (77K) of chloroplasts from Giymatli-2/17 under water deficiency, and there is a stimulation of the ratio of fluorescence band intensity F687/F740. After exposure to drought, cv. Giymatli-2/17 shows a larger reduction in the actual PS II photochemical efficiency of chloroplasts than cv. Azamatli-95.

Protein composition and native state of pigments of thylakoid membrane of wheat genotypes differently tolerant to water stress.

Protein composition and native state of chlorophylls were analyzed in two wheat (Triticum durum L.) genotypes with different tolerance to drought, Barakatli-95 (drought-tolerant) and Garagylchyg-2 (drought-sensitive), during water deficit. It is shown that the plants subjected to water deficit appear to have a slight increase in alpha- and beta-subunits of CF1 ATP-synthase complex (57.5 and 55 kD, respectively) in Barakatli-95 and their lower content in Garagylchyg-2. Steady-state levels of the core antenna of PS II (CP47 and CP43) and light-harvesting Chl a/b-apoproteins (LHC) II in the 29.5-24 kD region remained more or less unchanged in both wheat genotypes. The synthesis of 36 kD protein and content of low-molecular-weight polypeptides (21.5, 16.5, and 14 kD) were noticeably increased in the tolerant genotype Barakatli-95. Drought caused significant changes in the carotenoid region of the spectrum (400-500 nm) in drought-sensitive genotype Garagylchyg-2 (especially in the content of pigments of the violaxanthin cycle). A shift of the main band from 740-742 to 738 nm is observed in the fluorescence spectra (77 K) of chloroplasts from both genotypes under water deficiency, and there is a stimulation of the ratio of fluorescence band intensity F687/F740.

Assembly of pigment-protein complexes in carotenoid-deficient membranes of plastids from wheat seedlings treated with norflurazon.

The pyridazinone-type herbicide norflurazon SAN 9789 inhibiting the biosynthesis of long-chain carotenoids results in significant decrease in PS II core complexes and content of light-harvesting complex (LHC) polypeptides. At the same time, early light-induced proteins (ELIP) with molecular masses of 20.5-16.5 and 13.5 kD disappear in norflurazon-treated seedlings grown under intermittent (pulsed) light, confirming the hypothesis that they are carotenoid-binding proteins. Full disappearance of Chl a forms at 668, 676, and 690 nm and a sharp decrease in Chl b form at 648 nm in treated seedlings grown under 30 or 100 lx light intensity shows close contact of these forms with carotenoids in the thylakoid membrane. The band shift from 740 to 720 nm in the low-temperature fluorescence spectrum (77 K) suggests a disturbance of energy transfer from LHC to the Chl a form at 710-712 nm.