Polymer-bound alkyltriazenes for mild racemization-free esterification of amino acid and peptide derivatives.

A novel tool for polymer-assisted solution phase (PASP) esterification of amino acid and peptide derivatives has been developed. When treated with carboxylic acids, polymer-bound alkyltriazenes react with a loss of nitrogen and transfer of the alkyl moiety to the carboxylate anion to form the corresponding alkyl esters. There are no limitations with regard to either the protecting groups or the nature of the amino acid. Furthermore no racemization occurs at the chiral centers of the amino acids as demonstrated by chiral GC-MS analyses. Alkyltriazene-resins were also applied successfully to the esterification of peptide acids and other peptidic structures, such as tripalmitoyl-S-glyceryl-cysteine (Pam3Cys). The triazene-mediated esterification reaction is exceptionally mild, and there is no need for prior activation of the carboxy groups. This method is therefore particularly suitable for the alkylation of complex peptidomimetic structures prone to racemization and for acid-sensitive structures.     

Protein,amino acid and mineral composition of some edible insects from Thailand

This paper focuses on the nutritional profiles of four edible insects from Thailand: the Bombay locust, scarab beetle, house cricket, and mulberry silkworm.The insects were ‘high’ in protein ranging from 27 g to 54 g/100 g edible portion in fresh weight basis, however, only the silkworm met the FAO/WHO requirements of 40% essential amino acids and 0.6 ratio of essential to non-essential amino acids. Tryptophan is the limiting amino acid in the locust and cricket, lysine in the scarab beetle, and leucine in the silkworm.The locust is a ‘source’ of iron and is ‘high’ in zinc, while the scarab beetle is a ‘source’ of magnesium and is ‘high’ in iron and zinc. The cricket bought from the street is a ‘source’ of iron and magnesium and is ‘high’ in zinc, while the cricket from the supermarket is a ‘source’ of calcium (the only one among the insect samples) and is ‘high’ in iron, magnesium and zinc. And lastly, the silkworm, regardless of where it was purchased, is a ‘source’ of iron and is ‘high’ in magnesium and zinc. The arsenic, cadmium, lead and mercury content of all the insect samples were well below the maximum values and are deemed safe for consumption as either feed material or complete feed.Edible insects can contribute to people's nutrient requirements and should be sustainably utilized. Aside from direct consumption, there is a huge potential for using the insects as raw material and fortificant in food processing.     

Chymotrypsin catalysed synthesis of fluorescent amino acid amide and peptide derivatives

Chymotrypsin catalyses a condensation reaction between 1-methyl-3,4-dihydro-beta-carboline-3-methyl carboxylate and amino acid amides or peptides, yielding fluorescent derivatives. During the peptide bond formation, the enzyme ensures the reaction's steric control of both carboxyl and amino components.     

The amino acid composition and some properties of histones

Some of the properties and the amino acid compositions of the histones of calf thymus, calf liver, fowl erythrocytes, and of a protamine-like material isolated from rooster sperm were described. The amino acid compositions of the histones were rather similar except that no methionine was found in the fowl erythrocyte histone. In the fowl, histones are found in the somatic chromosomes and protamines are found in the sperm chromosomes. This shows that great variations in chromosome composition can exist in an organism. Histone is digested by pepsin both when isolated and when in the chromosome.     

Ligand exchange amino acid analysis: resolution of some amino sugars and cysteine derivatives

A new buffer system has been developed for the Hitachi Perkin-Elmer model KLA-3B ligand-exchange amino acid analyzer (protein-hydrolyzates analysis) which allowed for virtually complete resolution of glucosamine and either mannosamine or galactosamine from the basic amino acids tyrosine and phenylalanine. The same buffer resolved S-(β-aminoethyl)cysteine from histidine. Although the resolution of the amino sugars was not affected by small pH changes in the buffer, the retention time of histidine was markedly changed. Elevation of the pH by 0.06 units caused histidine to elute with S-(β-aminoethyl)cysteine, while a similar decrease in pH caused it to elute with ammonia.     

Biological activity of two juvenoids and two ecdysteroids against three stored product insects

The insecticidal activity of juvenile hormone agonists methoprene and pyriproxyfen, and the ecdysone agonists RH-5849 and tebufenozide was evaluated against susceptible and actellic-resistant strains of Tribolium castaneum and susceptible strains of Rhyzopertha dominica and Sitophilus oryzae. Concentrations ranging from 0.1 to 20 ppm of the analogues were mixed in the food medium to which the tested insects were exposed. The results showed that all these compounds could affect the development of the tested species to differing extents but had no effect on the mortality of parental adults. The two JH analogues did not prolong the life span of R. dominica and S. oryzae, but very greatly extended that of T. castaneum. The extension led to the production of giant larvae and failure to pupate. Actellic-resistant strain of T. castaneum showed some cross-resistance to methoprene and pyriproxyfen, but not to RH-5849 and tebufenozide. Pyriproxyfen was the most effective compound among the four IGRs; a concentration of 0.1 ppm could completely inhibit the F(1) adult occurrence of both S- and R-strains of T. castaneum and its LC(90)s for controlling R. dominica and S. oryzae were 0.1 and 1.2 ppm, respectively. Methoprene was highly effective against R. dominica, but less active on S. oryzae. RH-5849 could achieve almost complete control of F(1) adults of T. castaneum and R. dominica at 10 ppm, but was less potent on S. oryzae. Tebufenozide appeared to be much less active on these three species compared with the other three compounds. The percentage reductions of F(1) adults for S- and R-strains of T. castaneum at a concentration of 20 ppm were 80 and 99%, respectively.     

我国仓储昆虫研究和防治的回顾与展望

与人类生活和经济发展密切相关的各类农产品,在其储藏期间和加工过程中常遭受仓储昆虫的严重为害。至今全世界已记载的仓储昆虫和螨类约500种,我国有383种,其中仓储昆虫242种,螨类141种。昆虫和螨类二者在储藏物中的栖境、食性和危害性基本相似,因此常通称为仓储害虫。它们多数潜藏在仓库、厂房、贷栈、商店、居室、图书馆、档案馆等处,为害储藏粮食、油料、动植物食品、中药材、烟草、棉、麻、丝、皮毛、呢料、图书、档案、纸质文物、竹木及其制品、电缆、塑料以及进出口贸易中的检疫商品等,造成很大损失。如粮油储藏期每年因虫害损…     

Triple helices formed by polyuridylic acid with some amino deoxyadenosine derivatives

Summary The stability of helical structures formed by polyuridylic acid with nucleosides and nucleotides derived from adenosine is not significantly affected by replacing hydroxyl groups by hydrogen, amino, or azido functions. Stability is affected by the position of the phosphate group.     

An optimized FM-index library for nucleotide and amino acid search

In computational structural biology, structure comparison is fundamental for our understanding of proteins. Structure comparison is, e.g., algorithmically the starting point for computational studies of structural evolution and it guides our efforts to predict protein structures from their amino acid sequences. Most methods for structural alignment of protein structures optimize the distances between aligned and superimposed residue pairs, i.e., the distances traveled by the aligned and superimposed residues during linear interpolation. Considering such a linear interpolation, these methods do not differentiate if there is room for the interpolation, if it causes steric clashes, or more severely, if it changes the topology of the compared protein backbone curves. To distinguish such cases, we analyze the linear interpolation between two aligned and superimposed backbones. We quantify the amount of steric clashes and find all self-intersections in a linear backbone interpolation. To determine if the self-intersections alter the protein’s backbone curve significantly or not, we present a path-finding algorithm that checks if there exists a self-avoiding path in a neighborhood of the linear interpolation. A new path is constructed by altering the linear interpolation using a novel interpretation of Reidemeister moves from knot theory working on three-dimensional curves rather than on knot diagrams. Either the algorithm finds a self-avoiding path or it returns a smallest set of essential self-intersections. Each of these indicates a significant difference between the folds of the aligned protein structures. As expected, we find at least one essential self-intersection separating most unknotted structures from a knotted structure, and we find even larger motions in proteins connected by obstruction free linear interpolations. We also find examples of homologous proteins that are differently threaded, and we find many distinct folds connected by longer but simple deformations. TM-align is one of the most restrictive alignment programs. With standard parameters, it only aligns residues superimposed within 5 Ångström distance. We find 42165 topological obstructions between aligned parts in 142068 TM-alignments. Thus, this restrictive alignment procedure still allows topological dissimilarity of the aligned parts. Based on the data we conclude that our program ProteinAlignmentObstruction provides significant additional information to alignment scores based solely on distances between aligned and superimposed residue pairs.     

A film technique for the biological evaluation of pyrethrum-in-oil insecticides for use against stored product insects in warehouses

There is need for a technique whereby a given insecticidal preparation can be compared with a standard containing 0.8% (w/v) pyrethrin 1 in a heavy white oil and pronounced biologically equal or inferior to the standard within known and reasonable limits. A film method was investigated, Tribolium castaneum beetles being used as the test insects.
Numerous factors which may influence the kill achieved are discussed. The results of preliminary work, planned to help in the standardization of some of these factors, are summarized.
Several materials were tested to ascertain their suitability for reception of the insecticidal film and, as thin greaseproof paper showed promise, its possibilities were explored. Although 0.3 % pyrethrin I could be distinguished from 0.4%, 0.5% could not be distinguished from 0.8%, and the results throughout were very heterogeneous.
Woven Nylon proved more satisfactory, since the test just failed to establish a significant difference between 0.6 and 0.8% pyrethrin 1. The origin of a pink coloration of the substrate, when T. castaneum beetles were confined on Nylon sprayed with pyrethrum in oil, was investigated.
Whatman filter paper no. 544 proved the best substrate, and a comparative test on it will distinguish 0.65% pyrethrin 1 from the standard 0.8%; the limit could probably be raised to 0.7%.
The influence of several factors on the homogeneity of the results was investigated, and the importance was shown of allowing beetles time to recover from the mechanical shock inherent in the method of counting into batches.
Directions are given for carrying out the film technique for comparing preparations of relatively high pyrethrin content. The method does not measure the direct spray or fumigant action of the insecticide.
The technique described is compared with the Peet-Grady method for evaluating liquid household insecticides of low pyrethrin content. A simplified, but less accurate, design for the test is indicated.     

Purification, amino acid sequence, and some properties of rabbit kidney lysozyme

The lysozyme (rabbit kidney lysozyme) from the homogenate of rabbit kidney (Japanese white) was purified by repeated cation-exchange chromatography on Bio-Rex 70. The amino acid sequence was determined by automated gas-phase Edman degradation of the peptides obtained from the digestion of reduced and S-carboxymethylated rabbit lysozyme with Achromobacter protease I (lysyl endopeptidase). The sequence thus determined was KIYERCELARTLKKLGLDGYKGVSLANWMCLAKWESSYNTRATNYNPGDKSTDYGIFQ INSRYWCNDGKTPRAVNACHIPCSDLLKDDITQAVACAKRVVSDPQGIRAWVAWRNHCQ NQDLTPYIRGCGV, indicating 25 amino acid substitutions from human lysozyme. The lytic activity of rabbit lysozyme against Micrococcus lysodeikticus at pH 7, ionic strength of 0.1, and 30 degrees C was found to be 190 and 60% of those of hen and human lysozymes, respectively. The lytic activity-pH profile of rabbit lysozyme was slightly different from those of hen and human lysozymes. While hen and human lysozymes had wide optimum activities at around pH 5.5-8.5, the optimum activity of rabbit lysozyme was at around pH 5.5-7.0. The high proline content (five residues per molecule compared with two prolines per molecule in hen or human lysozyme) is one of the interesting features of rabbit lysozyme. The transition temperatures for the unfolding of rabbit, human, and hen lysozymes in 3 M guanidine hydrochloride at pH 5.5 were 51.2, 45.5, and 45.4 degrees C, respectively, indicating that rabbit lysozyme is stabler than the other two lysozymes. The high proline content may be responsible for the increased stability of rabbit lysozyme.     

Unusual amino acids VIII. Asymmetric hydrogenation of some heteroaryl-N-CBZ and N-BOC aminocinnamic acid derivatives

Summary (Z)--[(Benzyloxy)- or (tert.-butyloxy)carbonylamino]- (thienyl)-or (furyl)-acrylic acids and their esters were prepared by known methods and hydrogenated to the corresponding optically active alanine derivatives with optical yields in the range of 58–93% ee using the cationic rhodium complex of PROPRAPHOS.     

Reductive N,N-dimethylation of amino acid and peptide derivatives using methanol as the carbonyl source

Formaldehyde is readily formed from methanol in the presence of palladium-on-charcoal and air. The use of this methanolic formaldehyde solution for the reductive methylation of amino groups in amino acid and peptide derivatives by catalytic hydrogenation has been studied and found to be superior to the use of aqueous formaldehyde because no contaminating paraformaldehyde is present. Some data on N-isopropylation are given.     

Algorithms for the search of amino acid patterns in nucleic acid sequences.

Some algorithms are described for the search of regions in a nucleic acid sequence that, when translated into amino acids, are homologous to a given amino acid pattern. All algorithms are modifications of the dynamic programming method for sequence comparison such that the translation of codons is taken into account. One of the algorithms has been implemented as a FORTRAN 77 program. The program operates on files that follow the format of the EMBL Nucleotide Sequence Data Library.     

Leishmanicidal activity of amino acid and peptide esters

Amino acid and dipeptide esters kill intracellular and isolated L. amazonensis amastigotes. Several o f the compounds also restrict the growth o f mouse lesions after intralesional administration. However, the esters are known to be toxic in vitro for monocytes and certain lymphoid cells. Michel Rabinovitch surveys the mechanisms o f the leishmanicidal activity, describes some structure--activity relationships, and discusses strategies for the design of compounds more selective for the parasite.