Search results for "Spar"
showing 10 items of 1739 documents
Salt effects on the protonation of l-histidine and l-aspartic acid: a complex formation model
1991
Abstract Protonation constants of l -histidine (histidinate: his − ) and l -aspartic acid (aspartate: asp 2− ) were determined potentiometrically, using the (H + ) glass electrode, in aqueous tetraethylammonium iodide (Et 4 NI), calcium chloride and sodium chloride solutions, at 0 −3 and 10 ⩽, T ⩽, 45 ° C. Differences in protonation constants determined in different salt media were explained by a complex formation model and, according to this model, the presence of the following species was hypothesized: Ca(his) + , CaH(his) 2+ , CaH 2 (his) 3+ Na(his) 0 , H 3 (his)X + , H 2 (his)X 0 , Et 4 N(his) 0 , Et 4 NH(his) + , Ca(asp) 0 , CaH(asp) + , CaH 2 (asp) 2+ , Na(asp) − , NaH(asp) 0 , H 3 (a…
pH-sensitive hydrogel based on a polyaspartamide derivative
2006
A pH-sensitive hydrogel was prepared by UV irradiation technique. Starting polymer was obtained from alpha,beta-poly (N-2-hydroxyethyl)-DL-aspartamide (PHEA) partially derivatized with glycidyl methacrylate (PHG). The PHG copolymer was cross-linked by UV irradiation in the presence of methacrylic acid (MA) to form a pH sensitive hydrogel. The cross-linked matrix shaped as microparticles was characterized by FT-IR spectrophotometry, XPS, X-ray diffraction, SEM and particle size distribution analyses. Moreover, to have information about water affinity of the prepared sample, swelling measurements were carried out in aqueous media mimicking some biological fluids. In order to employ the prepar…
Studies on the Content of Free Amino Acids in Needles of Undamaged and Damaged Spruce Trees at a Natural Habitat
1990
Summary Measurements of the amino acids in needles of undamaged and damaged 90-year-old spruce trees ( Picea abies ) showed different patterns. During the summer months a reduction in total amino acid content of about 60 % was found. In autumn the content of total amino acids rose again. The courses of the single amino acids behave similarly to that of the total amino acids. Quantitatively, the main amino acids were GLU, ASP and GLN with about 37 %, 21 % and 10 %, respectively, followed by PRO, ALA and SER with about 3–4 % each. In the needles of healthy trees large variations in ARG content could be observed. These variations correlate neither with the damage degree of the trees nor with t…
Protein and amino acid composition of the tergal gland secretions ofBlatta orientalis andEurycotis floridana (Dictyoptera: Blattidae)
1994
Summary Nymphs and adult females ofBlatta orientalis and nymphs ofEurycotis floridana produce a proteinaceous sticky secretion which accumulates on the last abdominal tergites. The proteic patterns do not differ between individuals of the same species. HPLC analyses show that all the common amino acids are found in both species, aspartic and glutamic acids representing 24 to 37% of the total amount of amino acids. InB. orientalis, glutamic acid is the more abundant amino acid whereas inE. floridana it is the aspartic acid. The secretion appears and accumulates rapidly on isolated insects. Behavioural assays revealed that these secretions have a defensive role.
Reducing of acrylamide formation in wheat biscuits supplemented with flaxseed and lupine
2016
Abstract The use of pseudo-cereals for wheat products making is to fortify the deficiency of nutritional value in wheat flour. However rich in proteins plant additives could increase acrylamide content in baked products. The present study was focused on acrylamide reduction in wheat flour biscuits supplemented with lupine and defatted flaxseed flour treated by solid state (SSF) and submerged (SMF) fermentations by Lactobacillus sakei , Pediococcus pentosaceus and Pediococcus acidilactici strains. After fermentation the decrease in asparagine was on average of 67.6 and 80.6%, and reducing sugar contents were reduced by 18 and 79.4% in flaxseed and lupine, respectively. The most effective acr…
Hydrophilic and hydrophobic copolymers of a polyasparthylhydrazide bearing positive charges as vector for gene therapy
2008
BACKGROUND: The design of polymeric vectors for gene delivery provided with specific properties is one of the most critical aspects for a successful gene therapy. These polymers should be biocompatible as well as able to carry efficiently DNA to target tissues and to transfect it into cells. RESULTS: The formation of complexes of poly[(α,β-asparthylhydrazide)–poly(ethylene glycol)] and poly[(α,β-asparthylhydrazide)–hexadecylamine] copolymers functionalised with glycidyltrimethylammonium chloride (PAHy–PEG-GTA and PAHy–C16-GTA, respectively) with DNA was studied. The effects of the introduction of hydrophilic (PEG) or hydrophobic (C16) moieties on the chains of PAHy–GTA copolymers, such as t…
ChemInform Abstract: O-Boronato- and o-Trifluoroborato-Phosphonium Salts Supported by L-α-Amino Acid Side Chain.
2015
The synthesis of o-boronato- and o-trifluoroborato–phosphonium salts supported by the l-amino acid side chain is described. The synthesis of these new class of amino acid derivatives was achieved by stereoselective quaternization of o-(pinacolato)boronatophenylphosphine with β- or γ-iodo amino acid derivatives which are prepared from l-serine or l-aspartic acid, respectively. The quaternization of the phosphine was performed using either iodo amino ester or carboxylic acid derivatives. In addition, free carboxylic acid and amine derivatives were obtained by saponification or HCl acidolysis of o-boronato–phosphonium amino esters, respectively. The usefulness of these compounds in peptide cou…