KINETICS OF DIMER FORMATION AND PHOTOHYDRATION IN ULTRAVIOLET-IRRADIATED POLYURIDYLIC ACID

Abstract— The decrease in absorbance at 2600 Å of poly-U following u.v. irradiation is analyzed quantitatively in terms of uracil-dimer formation and photohydration of uracil residues. At all wave lengths tested between 2300 and 2800 Å both dirner formation and hydration occur as well as dimer breakage. The cross section for uracil dirner breakage is large at 2300 and decreases to a relatively small value at 2800 Å. Consequently, at the shorter wave lengths the steady state for dimer formation and breakage is reached at lower doses than for the longer wave lengths. Absorbance decreases caused by longer wave lengths can be partially restored by irradiation with 2380 Å. At high doses, for all wave lengths, the main photoproducts are hydrated uracil residues. The maximum number of dimers that may be formed increases with wavelength. The absorbance loss caused by photohydration may be reversed by acidification and heat. For 2650 Å irradiation, 95 per cent of the absorbance is restored by a combination of the 2380 Å and thermal treatment. The values for the photochemical reactions of poly-U are fairly close to those for poly-T and for uridine.     

Gas-Phase Binding of Noncovalent Complexes Between α-cyclodextrin and Amino Acids Investigated by Mass Spectrometry

Noncovalent complexes between cyclodextrins and small molecules have been extensively studied recently because of their widespread application in the pharmaceutical industry for chiral and molecular recognition. To date, gas phase noncovalent binding affinities between α-cyclodextrin and amino acids have not been widely investigated. In this study, gas-phase binding of noncovalent complexes between α-CD and amino acids was investigated by electrospray ionization mass spectrometry (ESI-MS), demonstrating the formation of 1:1 stoichiometric noncovalent complexes. The binding of the complexes were further confirmed by collision-induced dissociation by tandem mass spectrometry. Mass spectrometric titrations between α-cyclodextrin and phenylalanine, glutamic acid, and arginine were performed to provide binding constants (lgK_a) as references for competitive ESI-MS. Calibration curves for the complexes of α-cyclodextrin with phenylalanine, glutamic acid, and arginine were plotted. Through competitive ESI-MS, the lgK_a for the complexes of α-CD with aspartic acid, lysine, proline, glycine, alanine, asparagine, cystine, glutamine, histidine, leucine, isoleucine, methionine, serine, threonine, and valine were measured directly. By comparison, it is seen that the measured binding constants for the complexes of α-cyclodextrin with basic amino acids such as arginine and lysine are lower than those for most complexes of neutral amino acids. The chiral selectivity of α-cyclodextrin for L- and D-isomers of methionine, threonine, asparagine, and phenylalanine determined by ESI-MS revealed its application as a chiral selector.     

Analysis of cyclic pyrolysis products formed from amino acid monomer

Amino acid was mixed with silica and tetramethylammonium hydroxide (TMAH) to favor pyrolysis of amino acid monomer. The pyrolysis products formed from amino acid monomer were using GC/MS and GC. 20 amino acids of alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine were analyzed. The pyrolysis products were divided into cyclic and non-cyclic products. Among the 20 amino acids, arginine, asparagine, glutamic acid, glutamine, histidine, lysine, and phenylalanine generated cyclic pyrolysis products of the monomer. New cyclic pyrolysis products were formed by isolation of amino acid monomers. They commonly had polar side functional groups to 5-, 6-, or 7-membered ring structure. Arginine, asparagine, glutamic acid, glutamine, histidine, and phenylalanine generated only 5- or 6-membered ring products. However, lysine generated both 6- and 7-membered ring compounds. Variations of the relative intensities of the cyclic pyrolysis products with the pyrolysis temperature and amino acid concentration were also investigated.     

Polyamide Layer Chromatography. Identification of Amino Acids in Angelica acutiloba Kitagawa via DNP Derivative

Eighteen amino acids; proline, alanine, valine, leucine, isoleucine, hydroxyproline, phenylalanine, ornithine, glycine, serine, aspartic acid, glutamic acid, threonine, asparagine, lysine, tyrosine, tryptophan, and arginine were identified by polyamide layer chromatography via DNP (dinitrophenly) derivatives in Angelica acutiloba Kitagawa (Tang-Kwei)     

Photochemistry of tobacco mosaic virus RNA. Effect of HCN

Abstract— In attempting to sort out possible mechanisms of photoreactivation of tobacco mosaic virus RNA (TMV-RNA) inactivated by ultraviolet radiation (u.v.) in buffer of ionic strength 0.25, we have investigated the effect of HCN on the quantum yield for u.v. inactivation of TMV-RNA and on the percent photoreactivation of inactivated TMV-RNA. Some photo-products produced by irradiation of model substances, polyuridylic acid (poly U) and polycytidylic acid (poly C), in the presence of HCN have also been studied. The ratio of the quantum yield for inactivation of TMV-RNA in the presence of HCN to that in the absence of HCN is 1.5, under non-photoreactivating conditions. By comparison, the ratio of the initial rates of loss of uracil residues in poly U under comparable conditions is 1.6; by contrast, the rate of loss of cytosine residues in poly C is unaffected by HCN. This similarity of ratios between poly U and TMV-RNA suggests that two of the mechanisms of u.v. inactivation of TMV-RNA at high ionic strength are akin to known reactions of uracil residues in poly U, i.e. hydrate and dimer formation. The photohydration reaction in poly U, as measured by the heat reversal of hydrated residues to uracil residues, is almost abolished by HCN, and the rate of dimerization, as measured by the appearance of dimer containing oligonucleotides following enzymatic hydrolysis of irradiated poly U, is reduced to half by HCN. HCN does not affect the rate of hydration of cytosine residues in poly C. Since photoreactivation of RNA inactivated in presence of HCN is only 60 per cent of that in absence of HCN it is suggested that uracil dimers are somehow involved in photoreactivation of TMV-RNA inactivated at high ionic strength.     

The mass spectra of N-adamantoylpeptides

The N-adamantoyl derivatives of the esters of twenty-one di-peptides and eight tri-peptides containing the amino acids glycine, alanine, valine, leucine, isoleucine, proline, phenylalanine, glutamic acid, lysine, histidine, serine, threonine, methionine, S-benzylcysteine and tyrosine were prepared and their mass spectra determined. The spectra of all compounds were suitable for amino acid sequence determination. Mixtures containing N-adamantoyl dipeptide and tripeptide methyl esters were separated by thin-layer chromatography and the components identified by high resolution mass spectrometry. The mass spectrometric features of N-adamantoyl peptide esters are discussed and compared with those of other N-acyl peptide derivatives.     

Esterification of amino acids to n-butyl and isobutyl esters in aqueous solutions for their gas chromatographic analysis

Summary Amino acids have been esterified with n-butanol and isobutanol in the presence of perchloric acid. It has been established that in the concentration range of [H₂O]/[n-BuOH]=0.10–0.40 esterification can be utilized for the determination of alanine, glycine, valine, leucine, proline, methionine, aspartic acid, phenylalanine, tyrosine, glutamic acid, lysine, arginine, histidine and cystine. In the case of [H₂O]/[i-BuOH] =0.05–0.20 the esterification yield decreases from 100% to 70%, in proportion to the water content.     

The effect of neighboring charges on the helix forming ability of charged amino acids in proteins.

It has been found that the fraction of glutamic acid residues which are helical in proteins is larger than might be expected from the experimentally determined value of the helical stability constants of glutamic acid. In order to understand this difference, the effect of neighboring charged side chains on the glutamic acid residues in proteins of known structure is examined. It is found that a positively charged side chain four residues away from a glutamic acid greatly enhances its probability to be helical. Similar results are obtained for aspartic acid, lysine, arginine, and histidine.     

Amino Acid-Responsive Liquid Membrane Electrodes

Abstract

Amino acid responsive electrodes based on the use of their quaternary ammonium salts in a liquid membrane phase have been prepared for tryptophane, phenylalanine, leucine, methionine, valine, and glutamic acid.     

Classification of vegetable oils according to their botanical origin using amino acid profiles established by direct infusion mass spectrometry

Amino acid profiles, established by direct infusion mass spectrometry, have been used to classify vegetable oils according to their botanical origin. The proteins present in hazelnut, sunflower, corn, soybean, olive, avocado, peanut and grapeseed oils were precipitated with acetone, and the residue was hydrolyzed in acid medium, diluted in a hydrochloric acid/ethanol mixture, and infused into the mass spectrometer. The spectra of the hydrolyzed protein extracts showed [M+H]+ ions of the following amino acids: glycine, alanine, serine, proline, valine, threonine, cysteine, isoleucine + leucine, aspartic acid, lysine, glutamic acid, methionine, histidine, phenylalanine, arginine and tyrosine. These ions were used to construct linear discriminant analysis (LDA) models. The ratios of the ion signal intensities selected by pairs were used as predictors. With the sequential application of three LDA models, the eight botanical origin categories of the samples were well resolved.     

Effect of a modification site on the electron-transfer reaction of glucose oxidase hybrids modified with phenothiazine via a poly(ethylene oxide) spacer

Glucose oxidase [GOx-(PT-PEONH2)] hybrids are synthesized by attaching phenothiazine (PT) groups to aspartic and glutamic acid residues on the enzyme surface via poly(ethylene oxide) (PEO) spacers of different molecular weights. A fast oxidation of FADH2/FADH by PT+ with the aid of the local motion of a hydrophilic, long, flexible PEO spacer is achieved for the GOx-(PT-PEONH2) hybrids and yields greater electron-transfer (ET) rates than that for GOx-(PTNH2) hybrids, in which the PT groups are directly bonded to the GOx surface. The ET rate of GOx-(PT-PEONH2) hybrids depends on the molecular weight of PT-PEONH2, and the maximum is obtained at a molecular weight of 3000. The ET rates of GOx hybrids are compared in terms of the location of the PT modification and the length and structure of the spacer chain connection of the PT mediator to a surface amino acid residue. Greater ET rates are obtained for the modification at aspartic and glutamic acid residues than for the lysine modification when the PT groups are bonded directly or via a short PEO spacer chain. In contrast, no advantage of aspartic and glutamic acid residues over lysine residues in generating a fast oxidation of FADH2/FADH by PT+ is observed for GOx hybrids in which the PT groups are attached via longer PEO spacers. The long PEO spacer is able to compensate the disadvantage of lysine residues locating far from the FAD center in GOx hybrids whose mediation reactions are based on the so-called wipe mechanism.     

Capillary gas chromatography of tert-butyldimethlysilylamino acids with PTV injection

The programmable temperature vaporizing injector (PTV) has been used to study the effects of injection temperature and initial heating period on the FID response factors of TBDMS derivatives of 17 protein amino acids. The relative response factors were calculated for injection temperatures of 50°C, 90°C, 160°C, 220°C, and 260°C with different initial heating periods (1 s, 5 s, and 10 s) and the results compared with the values obtained for the calculated response factors obtained under classical split injection conditions (300°C, continuous). Except for expected peak broadening effects, the initial heating period does not seem to have significative effects on relative peak areas. The response to the derivatives of alanine, glycine, α-aminobutyric acid, valine, proline, methionine, cysteine, phenylalanine, asparagine, and arginine was only slightly affected by increasing the injection temperature whereas the response factors for the derivatives of serine, threonine, glutamic acid, lysine, histidine, tyrosine, and tryptophan were strongly dependent upon initial injection temperatures, decreasing rapidly at temperatures above 160°C. The cold split-splitless injection is clearly advantageous over the classical hot injection techniques for the analysis of this type of aminoacid derivative.     

Mixed-ligand complexes of copper with some amino-acids and malonate

The mixed-ligand complexes formed by copper(II) with an amino-acid (valine, threonine, isoleucine, aspartic acid, glutamic acid, lysine) and malonic acid have been investigated polarographically and their stability constants determined. The complexes are less stable than the corresponding complexes with oxalic acid instead of malonic, but also exhibit less disproportionation into the simple complexes, because the simple oxalate complexes are more stable than the malonate complexes.     

THE EFFECT OF CROSS-LINKING ON PHOTOCYCLING ACTIVITY OF BACTERIORHODOPSIN

Abstract— Purple membrane preparations from Halobacterium halobium were chemically modified with imidoesters. Dimethyl adipimidate (8.3 Å chain length) amidinates about five of the six free lysine residues whereas dimethyl suberimidate (11.3 Å) under the same conditions reacts with only 2–3 residues. Gel electrophoresis showed that the shorter chain length imidoesters were less effective than dimethyl suberimidate in oligomer formation. However, dimethyl adipimidate resulted in a more marked inhibition of the photoreaction activity. Monofunctional imidates, methyl acetimidate and methyl butyrimi-date, at comparable degrees of amidination, did not appreciably affect activity indicating that the presence of bulky groups on the exposed lysine residues does not cause the effects observed. Hence, the introduction of molecular mobility constraints by intramolecular cross-linking slows photocycling, and, therefore, inhibits proton pumping activity of bacteriorhodopsin. This indicates that conforma-tional changes of the protein moiety of bacteriorhodopsin occur during photocycling activity.     

小麦粉营养成分分析标准物质的研制

进行了小麦粉营养成分分析标准物质的研制。选用上海农业科学院作物研究所培育的“杨麦一号”小麦种子经脱壳、粉碎、过筛,用＾６０Ｃｏγ射线照射使其贮存稳定期达７年以上;用数理统计Ｆ检验法和ｔ检验法检验证明其均匀性良好;由９个单位共同协作定值,共定值１３７组,５４８个数据,经统计检验,小麦粉中粗蛋白质、粗淀粉、粗脂肪、氨基酸总量、天门冬氨酸、苏氨酸、丝氨酸、谷氨酸、甘氨酸、丙氨酸、缬氨酸、蛋氨酸、异亮氨酸     

Identification of garlic in old gildings by gas chromatography-mass spectrometry

The proteinaceous content of garlic (Allium sativum) was characterised according to its amino acid composition by using a gas chromatography-mass spectrometry (GC-MS) analytical procedure. The procedure was tested on fresh and aged garlic samples as well as on reference gilding specimens prepared according to old recipes. The proteinaceous pattern showed a characteristic distribution of amino acids with glutamic acid being the major component. The average amino acidic composition was: glutamic acid (Glu; 29%), aspartic acid (Asp; 17%), serine (Ser; 11%), alanine, glycine, valine, leucine, lysine and phenylalanine (Ala, Gly, Val, Leu, Lys and Phe; 5-6%), isoleucine, proline and tyrosine (Ile, Pro and Tyr; 2-3%), methionine and hydroxyproline (Met and Hyp; 0.5%). In order to distinguish this material from animal glue and egg, which are the other proteinaceous media commonly used in gilding techniques, a database of amino acid percentages of the three proteins was built up and submitted to principal component analysis. Three separate clusters were obtained, allowing the protein identification. The application of the procedure on several gilding samples from Italian wall and easel paintings (13th-17th century) permitted to evidence the use of garlic as a gluing agent.     

PHOTOREACTIONS AT 3655Å BETWEEN PYRIMIDINE BASES AND SKIN-PHOTOSENSITIZING FUROCOUMARINS

Abstract After irradiation at 3655 Å of an aqueous frozen solution containing thymine and psoralen, a new photocompound was isolated by column chromatography. It contains a furocoumarin and a pyrimidine-moiety linked together by the formation of a cyclobutane ring (see formulas II and III). By irradiation at 2537 Å in acetic acid solution, the photocompound breaks up again yielding psoralen and thymine. From an aqueous frozen solution containing cytosine and psoralen irradiated at 3655 Å, an analogous photocompound was obtained, which, however, consists of the addition to psoralen of a uracil molecule, instead of a cytosine one (IV, V). It has been stated that the hydrolytic deamination of the cytosine moiety to the uracil one takes place during the working up of the photocompound in aqueous solution after irradiation. Substances with properties similar to those above were obtained from bergapten (5-methoxy-psoralen) and thymine, from psoralen and thymidine or thymidylic acid, irradiated at 3655 Å.
The new substances may be considered as model compounds in explaining the photoreactions which take place between the skin-photosensitizing furocoumarins and DNA upon irradiation at 3655 Å.     

Effect of amino acids on inhibition of lactate dehydrogenase-X by gossypol

Gossypol acetic acid (GAA) has been shown to have male antifertility effects, but there are pronounced differences among animal species. In the search of endogenous effector molecules, which interfere with the functions of GAA, we have studied the in vitro effect of various amino acids on the inhibition of the purified LDH-X by GAA. Histidine, cysteine and glycine were shown to block the effect of GAA. The effects of these amino acids were concentration dependent. Histidine and glycine protection was found to be complex type in which both the Km and Vmax were decreased compared to control. Arginine, glutamic acid, phenylalanine and valine were found to be ineffective against the inhibitory action of GAA.     

Photochemical addition of amino acids and peptides to homopolyribonucleotides of the major DNA bases

Abstract— The photochemical quantum yields for addition of glycine and the L-amino acids commonly occurring in proteins (excluding proline) to polyadenylic acid, polycytidylic acid, polyguanylic acid and polyribothymidylic acid have been determined in deoxygenated phosphate buffer at Λ 254 nm and pH 7, using a fluorescamine assay technique. Polyadenylic acid was reactive with eleven of the twenty amino acids tested, with phenylalanine, tyrosine, glutamine, lysine and asparagine having the highest quantum yields. Polyguanylic acid reacted with sixteen amino acids; phenylalanine, arginine, cysteine, tyrosine, and lysine displayed the largest quantum yields. Polycytidylic acid showed reactivity with fifteen amino acids with lysine, phenylalanine, cysteine, tyrosine and arginine having the greatest quantum yields. Polyribothymidylic acid, reactive with fifteen of nineteen amino acids surveyed, showed the highest quantum yields for cysteine, phenylalanine, tyrosine, lysine and asparagine. None of the polynucleotides were reactive with aspartic acid or glutamic acid.
The quantum yields for photoaddition of eighteen dipeptides of the form glycyl X (X being one of the amino acids commonly occurring in proteins, including proline), and of L-alanyl-L-tryptophan, L-seryl-L-seryl-L-serine, L-threonyl-L-threonyl-L-threonine, L-cystine- bis -glycine, and N_α-acetyllysine to polyadenylic acid, polycytidylic acid and polyguanylic acid were measured. All of these were found to add photochemically to each of these polymers. Polyribothymidylic acid, tested with eleven of these peptides and with N_α-acetyllysine, was found to be reactive with all.