A Raman spectroscopic study of the complexation of the methylmercury(II) cation by amino acids

1987 ◽  
Vol 65 (3) ◽  
pp. 491-496 ◽  
Author(s):  
Serge Alex ◽  
Rodrigue Savoie
Keyword(s):  
Amino Acids ◽  
Spectroscopic Investigation ◽  
Thiol Group ◽  
Amino Groups ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Bending Mode ◽  
Stretching Vibration ◽  
Vibrational Bands ◽  
Cation Coordination

A systematic Raman spectroscopic investigation of the complexation of CH3Hg+ by the standard amino acids is reported. It is shown that the vibrational bands due to the ligand—Hg and Hg—CH3 stretching modes and to the symmetric —CH3 bending mode of the —HgCH3 unit are well suited to characterize the extent of complexation and the sites of attachment of the cation. Coordination, which occurs mostly on sulfur and nitrogen atoms by substitution of a proton on the thiol group of cysteine or on amino groups in general, is best identified by the frequency of the ligand—Hg stretching vibration in the 250–550 cm−1 region of the spectrum.

scholarly journals A Raman spectroscopic study of the natural carbonophosphates Na<sub>3</sub><i>M</i>CO<sub>3</sub>PO<sub>4</sub> (<i>M</i> is Mn, Fe, and Mg)

2021 ◽  
Vol 33 (3) ◽  
pp. 283-297
Author(s):  
Evgeniy Nikolaevich Kozlov ◽  
Ekaterina Nikolaevna Fomina ◽  
Vladimir Nikolaevich Bocharov ◽  
Mikhail Yurievich Sidorov ◽  
Natalia Sergeevna Vlasenko ◽  
...  
Keyword(s):  
Spectroscopic Study ◽  
General Formula ◽  
Raman Spectra ◽  
Crystallographic Orientation ◽  
Energy Dispersive ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Vibrational Bands

Abstract. Raman spectra of three natural carbonophosphates (sidorenkite, bonshtedtite, and bradleyite) with the general formula Na3MCO3PO4 (M is Mn, Fe, and Mg) were studied and compared. These spectra showed from 21 to 24 vibrational bands, of which the two most intense (964±5 and 1074±3 cm−1) correspond to the υ1(P–O) and υ1(C–O) modes. These two bands split into doublet peaks due to the occurrence of isomorphic impurities. It was found that the crystallographic orientation of the sample influences the intensity of most bands. Most bands assigned to the same vibrations showed a regular shift (the smallest in sidorenkite spectra, an intermediate in bonshtedtite, and the largest in bradleyite). We propose an algorithm that allows for diagnostics of carbonophosphates in inclusions by their Raman spectra, providing a reliable result even in the absence of energy-dispersive X-ray spectroscopy (EDX) data.

A Raman spectroscopic study of the natural carbonophosphates Na3MCO3PO4 (M = Mn, Fe, and Mg)

2021 ◽  
Author(s):  
Ekaterina Fomina ◽  
Evgeniy Kozlov ◽  
Mikhail Sidorov ◽  
Vladimir Bocharov
Keyword(s):  
Natural Increase ◽  
Mineral Species ◽  
Raman Shift ◽  
Russian Science ◽  
Epma Data ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Mineral Phases ◽  
Vibrational Bands ◽  
Global Carbon

&lt;p&gt;Along with some other Na-minerals, carbonophosphates indicate a high initial Na activity in carbonatite and kimberlite melts, which is beneficial for petrological reconstructions. Because carbonophosphates are capable of incorporating large-ion lithophile and rare earth elements (REEs) in their structure, they can participate in the transport of these elements. Moreover, due to the presence of both [PO&lt;sub&gt;4&lt;/sub&gt;]&lt;sup&gt;3&amp;#8722;&lt;/sup&gt; and [CO&lt;sub&gt;3&lt;/sub&gt;]&lt;sup&gt;2&amp;#8722; &lt;/sup&gt;groups in carbonophosphates, these mineral phases play an important role in the Earth's global carbon and phosphate cycles. With all these properties, carbonophosphates have long attracted the attention of geologists. Raman spectroscopy appears to be one of the most suitable tools for their diagnosis, since they commonly present in rocks as small inclusions in other mineral grains. Despite this profit, only a few publications contain Raman characteristics of either natural or synthetic carbonophosphates.&lt;/p&gt;&lt;p&gt;We studied and compared Raman spectra of three natural carbonophosphate phases (sidorenkite, bonshtedtite, and bradleyite) with the general formula Na&lt;sub&gt;3&lt;/sub&gt;MCO&lt;sub&gt;3&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; (M = Mn, Fe, and Mg, correspondingly). These spectra showed from 21 to 24 vibrational bands, of which the two most intense (963&amp;#177;5 cm&lt;sup&gt;-1&lt;/sup&gt; &amp;#1080; 1074&amp;#177;3 cm&lt;sup&gt;-1&lt;/sup&gt;) correspond to the &amp;#957;1(P&amp;#8211;O) and &amp;#957;1(C&amp;#8211;O) modes. These two bands split due to the occurrence of isomorphic impurities. It was found that the crystallographic orientation of the sample influences the intensity of most bands. A natural increase in the Raman shift was observed for most bands assigned to the same vibrations (the smallest shift in the spectrum is characteristic of sidorenkite, an intermediate - of bonshtedtite, and the largest - of bradleyite).&lt;/p&gt;&lt;p&gt;We propose the following algorithm for the diagnosis of carbonophosphates:&lt;/p&gt;&lt;ul&gt;&lt;li&gt;Checking minerals for belonging to the group of carbonophosphates by the main bands and the characteristic profile of the spectrum;&lt;/li&gt; &lt;li&gt;Testing the hypothesis that the mineral of question is bradleyite based on the analysis of the estimated shift of the main bands;&lt;/li&gt; &lt;li&gt;Diagnosis of a mineral species by peaks located between the main bands;&lt;/li&gt; &lt;li&gt;Validation of the diagnostics by considering the position of the bands at 185&amp;#177;9 cm&lt;sup&gt;-1&lt;/sup&gt;, 208&amp;#177;7 cm&lt;sup&gt;-1&lt;/sup&gt;, 255&amp;#177;5 cm&lt;sup&gt;-1&lt;/sup&gt;, and 725&amp;#177;6 cm&lt;sup&gt;-1&lt;/sup&gt;.&lt;/li&gt; &lt;/ul&gt;&lt;p&gt;The proposed algorithm allows one to perform Raman diagnostics of carbonophosphates in inclusions even in the absence of EPMA data. In the study of carbonatites, kimberlites, and other rocks, the diagnostics of the mineral species of the carbonophosphate group can be important in the petrological aspect.&lt;/p&gt;&lt;p&gt;This research was funded by the Russian Science Foundation, grant number 19-77-10039.&lt;/p&gt;

scholarly journals Influence of CNTs, ZnO, Gd2O3 and SiO2 on Calcium Silicate Hydrate: A Raman spectroscopic study

2021 ◽  
Author(s):  
Muhammad Azeem
Keyword(s):  
Metal Oxides ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Weight Percent ◽  
The Other ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
The Matrix ◽  
Vibrational Bands ◽  
Strength And Durability

Abstract Raman spectra are collated from the cement paste matrices of CNTs, ZnO, Gd2O3, and SiO2. The spectra show that CNTs do not take part in hydration process and therefore concentration of calcium silicate hydrate (CSH) is unchanged in CNT-OPC matrix. The metal oxides, on the other hand, have shown significant effects on the CSH concentration. The CSH concentration increases with the increase of ZnO weight percent in the matrix whereas spectra collected from Gd2O3 matrix shows the strongest CSH vibrational bands. Moreover, vibrational bands of CaCO3 also become weak in the matrices with Gd2O3. The addition of SiO2 however had opposite effects that is by increasing the weight percent of SiO2 in the matrix, the CSH concentration is decreased. Since CSH acts a glue in a binder, the study shows that its concentration can be controlled by adding foreign elements. Such binders are expected to show improved strength and durability.

scholarly journals o-Quinones formed in plant extracts. Their reactions with amino acids and peptides

1969 ◽  
Vol 112 (5) ◽  
pp. 609-616 ◽  
Author(s):  
W. S. Pierpoint
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plant Extracts ◽  
Thiol Group ◽  
Amino Group ◽  
Amino Groups ◽  
Terminal Amino Acid ◽  
Secondary Reactions ◽  
Terminal Amino ◽  
Group 5

1. The reactions of amino acids and peptides with the o-quinones produced by the enzymic oxidation of chlorogenic acid and caffeic acid have been studied manometrically and spectrophotometrically. 2. Amino acids, except lysine and cysteine, react primarily through their α-amino groups to give red or brown products. These reactions, which compete with the polymerization of the quinones, are followed by secondary reactions that may absorb oxygen and give products with other colours. 3. The ∈-amino group of lysine reacts with the o-quinones in a similar way. The thiol group of cysteine reacts with the quinones, without absorbing oxygen, giving colourless products. 4. Peptides containing cysteine react with the o-quinones through their thiol group. 5. Other peptides, such as glycyl-leucine and leucylglycine, react primarily through their α-amino group and the overall reaction resembles that of the N-terminal amino acid except that it is quicker. 6. With some peptides, the secondary reactions differ from those that occur between the o-quinones and the N-terminal amino acids. The colours produced from carnosine resemble those produced from histidine rather than those from β-alanine, and the reactions of prolylalanine with o-quinones are more complex than those of proline.

scholarly journals The measurement of amino groups in proteins and peptides

1971 ◽  
Vol 124 (3) ◽  
pp. 581-590 ◽  
Author(s):  
R Fields
Keyword(s):  
Amino Acids ◽  
Room Temperature ◽  
Thiol Group ◽  
Amino Group ◽  
Thiol Groups ◽  
Amino Groups ◽  
Model Compounds ◽  
Time Required ◽  
Short Time ◽  
Proteins And Peptides

A technique is examined for determining amino groups with 2,4,6-trinitrobenzenesulphonic acid, in which the extinction at 420nm of sulphite complexes of the trinitrophenylated amino groups is measured. The sensitivity of the method is 5–200nmol of amino group. The method is especially suitable for checking the extent of blocking or unblocking of amino groups in proteins and peptides, owing to the short time required for reaction (5min at room temperature). The reaction of the reagent with thiol groups has been studied and was found to proceed 30–50 times faster than with ∈-amino groups of model compounds. The ∈420 of a trinitrophenylated thiol group was found to be 2250m-1·cm-1. The reaction with several amino acids, peptides and proteins is presented. The ∈420 of a typical α-amino group was found to be 22000m-1·cm-1 and that of an ∈-amino group, 19200m-1·cm-1. Difficulties inherent in the analysis of constituent amino group reactions in proteins are discussed.

scholarly journals The use of arginine analogues for investigating the functional organization of the arginine-binding site in lobster muscle arginine kinase. Role of the ‘essential’ thiol group

1980 ◽  
Vol 185 (3) ◽  
pp. 593-599 ◽  
Author(s):  
David C. Watts ◽  
Emmanuel O. Anosike ◽  
Barbara Moreland ◽  
R. J. Pollitt ◽  
C. R. Lee
Keyword(s):  
Amino Acids ◽  
Carboxy Group ◽  
Functional Organization ◽  
Arginine Kinase ◽  
Thiol Group ◽  
Difference Spectrum ◽  
Carbon Chain ◽  
Amino Groups ◽  
Difference Spectra ◽  
Nitrobenzoic Acid

1. The nature of arginine binding to lobster arginine kinase and the extent of its possible involvement with the ‘essential’ thiol group of the enzyme has been investigated with some inhibitory analogues of arginine. 2. Most of the analogues inhibit competitively, although mixed inhibition may occur if the α-carboxy group or α-amino group is absent. 3. The Ki values indicate that strength of binding depends on the length of the carbon chain (l-isoleucine>l-valine>l- α-aminobutyrate>l-alanine) and the integrity of the substituents on the α-carbon atom (l-arginine>agmatine and l-ornithine>putrescine). The guanidino group probably contributes little to substrate binding, but a positive charge near the δ-nitrogen atom appears to be important (l-ornithine>l -citrulline>l-α-aminobutyrate). A cyclic analogue, 2-carboxymethyl-3-oxo-2,3,5,6,7,8-hexahydro-1H-imidazo [1,2-a][1,3]diazepine-8-carboxylic acid, has a low Ki value similar to that of an equivalent straight-chain form, suggesting that arginine probably binds in a folded configuration. 4. The aliphatic l-amino acids give enzyme difference spectra similar to that with l-arginine and the integrity of the α-carboxy and α-amino groups appears to be a minimal but not sufficient requirement for this, as l-ornithine gives an atypical difference spectrum. A difference spectrum is interpreted as indicating an enzyme conformational change. No difference spectrum was observed with methylguanidine. 5. The ability of aliphatic α-l-amino acids to protect against inhibition by 5,5′-dithiobis-(2-nitrobenzoic acid) is proportional to the number of atoms in the carbon chain and inversely proportional to Ki. Ornithine gives greater protection than citrulline; analogues lacking the α-amino groups also protect. Agmatine, lacking the α-carboxy group, did not protect. 6. It is concluded that it is unlikely that the ‘essential’ thiol group in the enzyme interacts with any part of the arginine molecule during catalysis except, possibly, the α-carboxyl group.

scholarly journals The Behavior of NH3+ Torsional Vibration in Amino Acids: A Raman Spectroscopic Study

Crystals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 517
Author(s):  
André Luís de Oliveira Cavaignac ◽  
Ricardo Jorge Cruz Lima ◽  
Paulo Tarso Cavalcante Freire
Keyword(s):  
Crystal Structure ◽  
Amino Acids ◽  
Hydrogen Bonds ◽  
Geometric Parameters ◽  
Positive Slope ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Arginine Hydrochloride ◽  
Temperature Lattice ◽  
The Stability

In this work we present the continuation of studies carried out on the changes of geometric parameters of the hydrogen bonds in amino acid crystals subjected to temperature or pressure variations. Changes in geometric parameters of the hydrogen bonds are correlated with the temperature behavior of the Raman wavenumber of NH3+ torsional band. Now four monocrystals, L-valine, L-isoleucine, taurine, and L-arginine hydrochloride monohydrate, are studied. Temperature evolution of the Raman wavenumber of NH3+ torsional band, with positive slope (dν/dT = 0.023 cm−1/K) of L-isoleucine, can be related to the stability of the crystal structure and the hydrogen bonds strengths on heating due to different temperature lattice parameters variation.

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