Hydration of clupeine in solution

Spin-lattice relaxation times, T1, of H2(17) O at 25 degrees were measured for aqueous solutions of clupeine and its constituent amino acids, which are serine, threonine, proline and arginine. The dynamic hydration numbers, nDHN, of clupeine and amino acids were determined from a concentration dependence of T1. The coordination numbers nh, and the rotational correlation times, tau ch, of water molecules around clupeine and amino acids were estimated and compared with that of pure water. The tau ch/tau co of clupeine was 1.85 and close to that of arginine. The experimental value of nDHN of clupeine was in good agreement with that calculated from the nDHN values of the constituent amino acids. This means that the clupeine molecule has a random conformation in solution.     

Carnosine and its constituents inhibit glycation of low-density lipoproteins that promotes foam cell formation in vitro

Glycation of low-density lipoprotein (LDL) by reactive aldehydes, such as glycolaldehyde, can result in the cellular accumulation of cholesterol in macrophages. In this study, it is shown that carnosine, or its constituent amino acids beta-alanine and l-histidine, can inhibit the modification of LDL by glycolaldehyde when present at equimolar concentrations to the modifying agent. This protective effect was accompanied by inhibition of cholesterol and cholesteryl ester accumulation in human monocyte-derived macrophages incubated with the glycated LDL. Thus, carnosine and its constituent amino acids may have therapeutic potential in preventing diabetes-induced atherosclerosis.     

Identification of heat-stable A-factor from Myxococcus xanthus.

The asg mutants of Myxococcus xanthus fail to produce a set of related substances called A-factor. A-factor is released into the medium and is required early in fruiting body development. Lacking A-factor, the asg mutants are defective in aggregation, sporulation, and expression of most genes whose products appear later than 1 h after development is induced by starvation. Previous work has shown that these defects are reversed when A-factor, released by developing wild-type cells, is added to asg mutant cells. Part of the material in conditioned medium with A-factor activity is heat stable and dialyzable. This low-molecular-weight A-factor consists of a mixture of amino acids and peptides. Fifteen single amino acids have A-factor activity, and 11 of these are found in conditioned medium. Mixtures of amino acids have a total activity approximately equal to the sum of the activities of their constituents. Conditioned medium also contains peptides with A-factor activity. Pure peptides have A-factor activity, and their specific activities are equal to or less than the sum of the activities of their constituent amino acids. There is no evidence for a specialized A-factor peptide in conditioned medium, one with a specific activity greater than the sum of its constituent amino acids. About half of the heat-stable A-factor activity in conditioned medium can be accounted for by free amino acids, and the remaining half can be accounted for by peptides. It is argued that heat-stable A-factor induces A-dependent gene expression not by the nutritional action of amino acids but through a chemosensory circuit.     

Inadequacy of prebiotic synthesis as origin of proteinous amino acids

Summary The production of some nonproteinous, and lack of production of other proteinous, amino acids in model prebiotic synthesis, along with the instability of glutamine and asparagine, suggest that not all of the 20 presentday proteinous amino acids gained entry into proteins directly from the primordial soup. Instead, a process of active co-evolution of the genetic code and its constituent amino acids would have to precede the final selection of these proteinous amino acids.     

Stimulatory effects of peptides on growth of the free-living nematode Caenorhabditis briggsae.

Evidence is presented that peptide products of hydrolysis of casein, including some di- and tripeptides, but not the constituent amino acids, can stimulate growth of C. briggsae in defined basal medium supplemented with cytochrome C and B-sitosterol. Peptide activity may raise from amino acid imbalances in the medium which causes competitive inhibition of uptake of essential amino acids. Such activity precludes facilitation of heme transport as the sole function of growth factor in C. briggsae. This is the first report in a nutritional role of peptides in invertebrate metazoa.     

Comparison of amino acids interaction with gold nanoparticle

The study of nanomaterial/biomolecule interface is an important emerging field in bionanoscience, and additionally in many biological processes such as hard-tissue growth and cell-surface adhesion. To have a deeper understanding of the amino acids/gold nanoparticle assemblies, the adsorption of these amino acids on the gold nanoparticles (GNPs) has been investigated via molecular dynamics simulation. In these simulations, all the constituent atoms of the nanoparticles were considered to be dynamic. The geometries of amino acids, when adsorbed on the nanoparticle, were studied and their flexibilities were compared with one another. The interaction of each of 20 amino acids was considered with 3 and 8 nm gold GNPs.     

Amino acids of the cell wall of Nocardia rubra

Two classes of preparations of cell walls of Nocardia rubra strain 721-A, digested by trypsin and pepsin with or without subsequent extraction in alkaline ethanol, when examined by electron microscope and analyzed quantitatively for amino acid content differ in ultrastructure and constituent amino acids. Evidence suggests that the lipid-associated amino acids (as peptide or protein) occupy a location superficial to the basal peptido-glycan layer of this nocardia. Their removal is associated with the loss of a characteristic pattern of the outer envelope.     

Possible role of hydrogen cyanide in chemical evolution investigation of the proposed direct synthesis of peptides from hydrogen cyanide

The compounds formed upon oligomerization of cyanide in aqueous solution have been separated into acidic, basic, amphoteric and neutral fractions. Urea is the major constituent of the neutral fraction and oxalic acid is present in the acidic fraction. The oligomerization mixtures isolated in the acid, basic and amphoteric fractions consist of low molecular weight substances which yield amino acids on acid hydrolysis. Citrulline has been identified as a major amino acid released on acid hydrolysis of the product mixture. No amino acids are released from the oligomerization mixture by pronase or carboxypeptidase A. This catalyzed hydrolysis demonstrates that this system does not contain compounds with peptide links. The oligomerization products are susceptible to oxidizing agents but are affected little by reducing agents.     

Immunoinformatics Insights into the Internalin A and B Proteins to Design a Multi-Epitope Subunit Vaccine for L. monocytogenes

International Journal of Peptide Research and Therapeutics - Amino acids are the principal constituent of peptides and proteins. The ever-going expansion beyond non-canonical amino acids is one of...     

ATP-synthase of bacteria, mitochondria, and chloroplasts. Properties of the F(0) membrane sector

An analysis of literary data concerning the physico-chemical properties of the hydrophobic fragment of bacterial, mitochondrial and chloroplast ATP-synthases has been carried out. The distribution patterns of enzyme subunits and of the whole enzyme complex are reviewed on the basis of amino acid analysis data taking account of physico-chemical characteristics of constituent amino acids. The roles of subunits, their invariant and other amino acids in the hydrophobic fragment function are discussed.     

A weighting method for predicting protein structural class from amino acid composition.

A protein is generally classified into one of the following four structural classes: all alpha, all beta, alpha+beta and alpha/beta. In this paper, based on the weighting to the 20 constituent amino acids, a new method is proposed for predicting the structural class of a protein according to its amino acid composition. The 20 weighting parameters, which reflect the different properties of the 20 constituent amino acids, have been obtained from a training set of proteins through the linear-programming approach. The rate of correct prediction for a training set of proteins by means of the new method was 100%, whereas the highest rate of previous methods was 82.8%. Furthermore, the results showed that the more numerous training proteins, the more effective the new method.     

zeta-Crystallin is a major protein in the lens of Camelus dromedarius

Camel (Camelus dromedarius) lenses contain a protein with an apparent subunit Mr 38,000 that constitutes approximately 8-13% of the total protein. The protein has been purified and has a native Mr 140,000 as determined by gel filtration. This is consistent with its being a tetramer. The protein reacts with antibodies raised against both guinea pig zeta-crystallin and peptides corresponding to amino acids 1-10 and 295-308, but not to antibodies raised against amino acids 320-328 of zeta-crystallin. Based on these criteria it is concluded that this protein, which is a major constituent of camel lens, is zeta-crystallin. This may be the first example of a protein (enzyme) being independently utilized as a crystallin in the lens of species from two mammalian orders.     

Non-ribosomal biosynthesis of the cyclic octadecapeptide alamethicin.

The biosynthesis of the cyclic octadecapeptide, alamethicin, in a cell-free system of Trichoderma viride has been investigated. It was shown that nucleic acid- and ribo-some-free extracts of Trichoderma viride could catalyze alamethicin biosynthesis. Puromycin, erythromycin and RNAse did not inhibit this synthesis. The Sephadex G 200 filtrate contains a fraction (Kav=0.1) that catalyzes the biosynthesis of alamethicin and shows an ATP-32PPi exchange with 6 of the 8 constituent amino acids of alamethicin. The activated amino acids are bound to the enzyme as aminoacyl adenylates and as thiolesters in a proportion of 1 : 1. About 50% of each bound amino acid could be split off with 7% TCA. The TCA-stable bound amino acid could be split by mercury acetate, hydroxylamine and performic acid. N-ethylmaleimide blocked the binding of 50% of the amino acids to the enzyme, proving that some of the amino acids first bound as aminoacyl adenylates are then transferred into a thiolester bond.     

Functional characterization of constituent enzyme fractions of mycobacillin synthetase.

The enzyme fraction A, a constituent enzyme of the three-fraction enzyme mycobacillin synthetase, independently and sequentially activated five amino acids starting from L-proline, producing the pentapeptide Pro(Asp1,Glu1,Tyr1)Asp. The fractions B and C were unable to function independently. However, the fraction B synthesized the nonapeptide Pro(Asp3,Glu1,Tyr2,Ser1)Leu, sequentially activating the pentapeptide and next four amino acids, whereas the fraction C synthesized mycobacillin by the sequential activation of the nonapeptide and the remaining four amino acids. The pH optima of the above enzymes are almost identical (pH 7.8), but their Km values are a little different.     

Bactericidal activity of LFchimera is stronger and less sensitive to ionic strength than its constituent lactoferricin and lactoferrampin peptides

The innate immunity factor lactoferrin harbours two antimicrobial moieties, lactoferricin and lactoferrampin, situated in close proximity in the N1 domain of the molecule. Most likely they cooperate in many of the beneficial activities of lactoferrin. To investigate whether chimerization of both peptides forms a functional unit we designed a chimerical structure containing lactoferricin amino acids 17-30 and lactoferrampin amino acids 265-284. The bactericidal activity of this LFchimera was found to be drastically stronger than that of the constituent peptides, as was demonstrated by the need for lower dose, shorter incubation time and less ionic strength dependency. Likewise, strongly enhanced interaction with negatively charged model membranes was found for the LFchimera relative to the constituent peptides. Thus, chimerization of the two antimicrobial peptides resembling their structural orientation in the native molecule strikingly improves their biological activity.     

Biosynthesis of cyclosporin A: partial purification and properties of a multifunctional enzyme from Tolypocladium inflatum

An enzyme fraction most probably involved in the biosynthesis of cyclosporin A was purified 540-fold from Tolypocladium inflatum. The enzyme was capable of forming covalent enzyme-substrate complexes and catalyzed the ATP-pyrophosphate exchange reactions dependent on the unmethylated constituent amino acids of cyclosporin A. Evidence was obtained that covalent binding of substrate amino acids occurred via thioester linkage. Furthermore, the N-methylation of thio-esterified valine, leucine, and glycine residues with S-adenosyl-L-methionine was demonstrated. De novo synthesis of cyclosporin A was not observed but the formation of the diketopiperazine cyclo-(D-Ala-MeLeu) from D-alanine and L-leucine under the consumption of ATP and S-adenosyl-L-methionine. This cyclodipeptide represents a partial sequence of cyclosporin A. Molecular mass determinations revealed the enzyme activity to be lying in the range of about 700 kDa.     

Separation of some glycyl dipeptides with the amino acid analyzer

The chromatographic behavior of 7 glycyl dipeptides under standard conditions of automatic amino acid analysis in 30–50° and 50° systems has been examined. We separated these peptides in 18 and 10.5 hr, respectively, and found that they never overlapped with the peak position of the constituent amino acids.     

γ-Glutamylwillardiine and γ-glutamylphenylalanylwillardiine from seeds of Fagus silvatica

γ-l-Glutamyl-l-willardiine [γ-l-glutamyl-3-(1-uracil)-l-l-alanine] and γ-glutamylphenylalanylwillardiine have been isolated from seeds of Fagus silvatica. The structures have been established by spectroscopy, hydrolysis to give the constituent amino acids, and for the tripeptide end-group determination and partial hydrolysis to give the two constituent dipeptides.