Protein and Peptide Letters - Volume 15, Issue 4, 2008

Peroxidases (EC 1.11.1.7; donor: hydrogen peroxide oxidoreductase) are part of a large group of enzymes. In this study, peroxidase, a primer antioxidant enzyme, was purified with 19.3 fold and 0.2% efficiency from cauliflower (Brassica oleracea L.) by ammonium sulphate precipitation, dialysis, CM-Sephadex ion-exchange chromatography and Sephadex G-25 purification steps. The substrate specificity of peroxidase was Read More

A precursor of ConBr, a glucose/mannose-binding plant lectin, was expressed in the yeast Pichia pastoris. Western blot analysis of transformed cells detected an intracellularly recombinant protein band with ca. 34.5 kDa. The recombinant protein was apparently active as suggested by its strong interaction with the mannose-rich yeast cell debris.

E. coli acetyl esterase (Aes) and β-cysthationase (MalY) interact, probably with the same mechanism, with the N-terminus of transcriptional activator of maltose regulon (MalT). In order to investigate the basic mechanism of this interaction, we used both a proteomic and a bioinformatic approach. Affinity-based mass spectrometry experiments with purified Aes protein as bait allowed to fish twenty-three, apparently speci Read More

244 point mutations have been recorded in human hemoglobin β-chain, of which some change the oxygen affinity of human hemoglobin β-chain. We use the amino-acid distribution probability to quantify these mutations, and use the cross-impact analysis with Bayes' law to determine the probability that changes the oxygen affinity of human hemoglobin β-chain under mutations.

We have previously characterized an acid-unfolded (UA) state of Mucor miehei lipase at pH 2. The effect of 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) resulted in characterization of molten-globule (MG) like states with β-sheet secondary structure at 15% (v/v) TFE and 6% (v/v) HFIP. α-Helical states accumulate at 80% (v/v) TFE and 30% (v/v) HFIP.

The sheep skins unhairing process with preliminary alkaline treatment of the wool leads to two unnatural dipeptide mimetics lysinoalanine (Lys* - Ala) and ornithinoalanine (Orn*- Ala) obtaining. They are result from the keratin hydrolysis process. The changes of wool keratin make it resistant to sulphide degradation. We synthesized and characterized these unnatural dipeptides under the experimental conditions. The structures a Read More

A series of N-phosphoryl dipeptide derivatives with trimethoxyaniline moiety were synthesized, in which compound 2a DIPP-Val-Phe-Ar exhibited the best inhibitory activity against K562 cells with the IC50 at 9.7 μM. Its antitumor effects are due to the induction of apoptosis which was further confirmed by morphological study and flow cytometry analysis.

The interaction between cholesterol and Human Serum Albumin (HSA) was studied by fluorescence technique. Addition of cholesterol causes decreasing of the fluorescence intensity of HSA and the mechanism can be attributed to static quenching. Both negative enthalpy and entropy change indicate this binding was an “enthalpy-driven” reaction. The number of binding site and distance between residues and ligands w Read More

Triose phosphate isomerase (TIM) was prepared and purified from chicken breast muscle. The equilibrium unfolding of TIM by urea was investigated by following the changes of intrinsic fluorescence and circular dichroism spectroscopy, and the equilibrium thermal unfolding by differential scanning calorimetry (DSC). Results show that the unfolding of TIM in urea is highly cooperative and no folding intermediate Read More

Peptides with more than one biological activity are many a times multifunctional peptides. Two peptides with multifunctional properties from αS2-casein were stabilized in presence of cosolvents for their biological activities like ACE inhibition activity and antioxidant activity. These bioactive peptides in cosolvents were also thermostable. Infra red spectra of peptides in cosolvents reveal no change in the secondary structure i Read More

Peroxidase from bitter gourd was purified by three step purification scheme; ammonium sulphate fractionation, gel filtration and affinity chromatography. The enzyme was purified 42 fold with the retention of 67% of the initial activity. The enzyme exhibited its maximum activity at pH 5.6 and 40 °C. The enzyme retained half of its activity even after 1 h incubation at 60 °C. Molecular weight of the purified glycosylated bi Read More

Advanced glycation end products (AGEs) are formed from the non-enzymatic reaction between reducing sugars and amine residues on proteins, lipoproteins or nucleic acids. AGEs are found on long-lived proteins and their tissue accumulation is associated with normal ageing. The formation of AGEs can be accelerated in certain pathological conditions such as diabetes where hyperglycaemia is present. AGE modification of pr Read More

The function of protein is closely correlated with it subcellular location. Prediction of subcellular location of apoptosis proteins is an important research area in post-genetic era because the knowledge of apoptosis proteins is useful to understand the mechanism of programmed cell death. Compared with the conventional amino acid composition (AAC), the Pseudo Amino Acid composition (PseAA) as originally introduced by Read More

The repetitive [RTRG]6 peptide was fortuitously identified as a potent nuclear localization signal when linked to the green fluorescent reporter protein. Replacing the arginines by lysines, or the threonines by glycines, both resulted in a decreased nuclear targeting ability of the peptide within this context. By contrast, the sequence [RT]12 proved able to drive nuclear accumulation of the linked protein as efficiently as the startin Read More

Bacillus strain CTP-09 yielded maximum productivity (1120 IU/L.h) of extracellular endoglucanase (CMCase) on 0.5% cellobiose after 10 h fermentation at 55° C. The purified enzyme is mono-meric in nature and exhibits stability up to 80° C and over a pH range (6.0-9.0). Activation energy, enthalpy and entropy of catalysis, and inactivation indicated that this CMCase is highly thermos-table. Purified enzyme possesse Read More

A novel antiretroviral protein Polygonatum cyrtonema lectin (PCL) belonging to the monocot mannose-binding lectin (MMBL) superfamily has been crystallized using hanging-drop vapor-diffusion method. The crystals diffract to 2.0 Å resolution and belong to space group P21, with unit-cell parameters of a=39.308 Å, b=48.317 Å, c=112.221 Å, and β=90.12° . Preliminary analysis indicates that the asymmetric unit contains f Read More

The Antarctic eubacterium Pseudoalteromonas haloplanktis (Ph) produces a cold-active iron superoxide dismutase (SOD). PhSOD is a homodimeric enzyme, that displays a high catalytic activity even at low temperature. Using hanging-drop vapour-diffusion technique, PhSOD has been successfully crystallized in two different crystal forms. Both crystal forms are monoclinic with space group P21 and diffract to 2.1 Å resol Read More

Galectin LEC-1 isolated from the nematode Caenorhabditis elegans was the first galectin found in invertebrates and also the first tandem-repeat-type galectin identified, containing two homologous carbohydrate-binding sites. This galectin is localized most abundantly in the adult cuticle and possibly plays a role in the formation of epidermal layers. We succeeded in crystallizing LEC-1 composed of 279 amino acids with a calcu Read More

Cytochrome P450 monooxygenases are a superfamily of heme-thiolate proteins involved in the metabolism of a wide variety of endogenous and xenobiotic compounds. The P450 enzyme CYP195A2 from Rhodopseudomonas palustris CGA009, a metabolically versatile bacterium, was overproduced in E. coli and purified. Two distinct crystal forms were obtained under separately optimized conditions by the hanging-drop Read More