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.

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 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 Ultraviolet Difference Spectra of Tyrosine Groups in Proteins and Amino Acids

1958 ◽  
Vol 233 (6) ◽  
pp. 1421-1428 ◽  
Author(s):  
Donald B. Wetlaufer ◽  
John T. Edsall ◽  
Barbara R. Hollingworth
Keyword(s):  
Amino Acids ◽  
Difference Spectra

The interaction of bovine milk caseins with the detergent sodium dodecyl sulphate. II. The effect of detergent binding on spectral properties of caseins

1970 ◽  
Vol 37 (2) ◽  
pp. 259-267 ◽  
Author(s):  
G. C. Cheeseman ◽  
Dorothy J. Knight
Keyword(s):  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Bovine Milk ◽  
Difference Spectrum ◽  
Temperature Dependent ◽  
Difference Spectra ◽  
Negative Change ◽  
Tryptophan Residues ◽  
Hydrophobic Binding ◽  
The Difference

SummaryThe dissociation of casein aggregates by the detergent sodium dodecyl sulphate (SDS) gave rise to difference spectra and these spectra were characteristic for each of the different types of casein. Increase in absorption by the chromophore groups, tyrosine and tryptophan, when αs1- and β-casein aggregates were dissociated indicated binding of the detergent at regions of the molecule containing these residues. A decrease in absorption when κ-casein was dissociated indicated that the tyrosine and tryptophan residues were not in the region of the molecule to which the detergent was bound and that in the κ-casein aggregate these residues were in a more hydrophobic environment. Peaks on the difference spectra were obtained at 280 and 288 nm for αs1-casein and 284 and 291 nm for β-casein and troughs at 278 and 286 nm for κ-casein. The difference spectrum reached a maximum value when the αsl- and β-casein aggregates were dissociated and the further binding of SDS did not alter this value. The large negative change in the difference spectrum of κ-casein did not occur until after most of the aggregates were dissociated and did not reach a maximum until binding with SDS was complete. The value obtained for ΔOD was found to be temperature-dependent for β-casein-SDS interaction, but not for αs1- and κ-casein. Changes in spectra were also observed when αs1- and κ-casein interacted to form aggregates. The data obtained confirmed the importance of hydrophobic binding in casein aggregate formation and indicated the possible involvement of tyrosine and tryptophan residues in this binding.

scholarly journals The principle of formaldehyde, alcohol, and acetone titrations. With a discussion of the proof and implication of the zwitterion conception

1934 ◽  
Vol 115 (792) ◽  
pp. 121-141 ◽  
Keyword(s):  
Amino Acids ◽  
Carboxyl Groups ◽  
Recent Discussion ◽  
Amino Groups ◽  
Chemical Methods ◽  
Titration Method ◽  
Physico Chemical ◽  
Empirical Argument ◽  
Chemical Evidence

Consideration of the implications of the zwitterion hypothesis of Bjerrum (1923) makes it desirable to state afresh the principles underlying the methods commonly employed in the titration of amino-acids. Deductions of considerable theoretical importance, cf., e. g ., Calvery (1933) are still being made on the supposition that the alkalimetric formaldehyde titration method of Sørensen (1907) and the corresponding alcohol method of Foreman (1920) and of Willstätter and Waldschmidt-Leitz (1921) estimate the carboxyl groups of amino-acids whilst the acidimetric acetone titration of Linderstrøm-Lang (1928) estimates the amino-groups. Yet the zwitterion hypothesis indicates that this assumption is the reverse of the truth. Discussion is greatly facilitated by collective consideration of recent physico-chemical evidence clarifying the principles upon which these common bio-chemical methods rest. In a recent discussion of two of the titrimetric methods (Van Slyke and Kirk, 1933) the existence of this evidence is ignored, so that it becomes necessary to systematize and elaborate the empirical argument of these authors in the light of the relevant investigations of Grünhut (1919), Cray and Westrip (1925), Michaelis and Mizutani (1925), Birch and Harris (1930, b ), and Levy (1933). At the same time new and useful developments are indicated.

scholarly journals Tracer studies on the biosynthesis of amino acids from lactate by Peptostreptococcus elsdenii

1967 ◽  
Vol 105 (1) ◽  
pp. 299-310 ◽  
Author(s):  
H. J. Somerville ◽  
J. L. Peel
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Aspartic Acid ◽  
Tricarboxylic Acid Cycle ◽  
Carbon Chain ◽  
Tricarboxylic Acid ◽  
Diaminopimelic Acid ◽  
Reaction Sequence ◽  
Tracer Studies ◽  
Cell Fractions

Peptostreptococcus elsdenii, a strict anaerobe from the rumen, was grown on a medium containing yeast extract and [1−14C]- or [2−14C]-lactate. Radioisotope from lactate was found in all cell fractions, but mainly in the protein. The label in the protein fraction was largely confined to a few amino acids: alanine, serine, aspartic acid, glutamic acid and diaminopimelic acid. The alanine, serine, aspartic acid and glutamic acid were separated, purified and degraded to establish the distribution of 14C from lactate within the amino acid molecules. The labelling patterns in alanine and serine suggested their formation from lactate without cleavage of the carbon chain. The pattern in aspartic acid suggested formation by condensation of a C3 unit derived directly from lactate with a C1 unit, probably carbon dioxide. The distribution in glutamic acid was consistent with two possible pathways of formation: (a) by the reactions of the tricarboxylic acid cycle leading from oxaloacetate to 2-oxoglutarate, followed by transamination; (b) by a pathway involving the reaction sequence 2 acetyl-CoA→crotonyl-CoA→glutaconate→glutamate.

scholarly journals Biodegradation of low molecular weight polyacrylamide under aerobic and anaerobic conditions: effect of the molecular weight

2020 ◽  
Vol 81 (2) ◽  
pp. 301-308 ◽  
Author(s):  
Wenzhe Song ◽  
Yu Zhang ◽  
Amir Hossein Hamidian ◽  
Min Yang
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Carbon Chain ◽  
Anaerobic Treatment ◽  
Low Molecular Weight ◽  
Amino Groups ◽  
Molecular Weights ◽  
Weight One ◽  
Hydrolysis Of ◽  
Aerobic And Anaerobic

Abstract The biodegradation of polyacrylamide (PAM) includes the hydrolysis of amino groups and cleavage of the carbon chain; however, the effect of molecular weight on the biodegradation needs further investigations. In this study, biodegradation of low molecular weight PAM (1.6 × 106 Da) was evaluated in two aerobic (25 °C and 40 °C) and two anaerobic (35 °C and 55 °C) reactors over 100 days. The removal of the low molecular weight PAM (52.0–52.6%) through the hydrolysis of amino groups by anaerobic treatment (35 °C and 55 °C) was much higher than that of the high molecular weight (2.2 × 107 Da, 11.2–17.0%) observed under the same conditions. The molecular weight was reduced from 1.6 × 106 to 6.45–7.42 × 105 Da for the low molecular weight PAM, while the high molecular weight PAM declined from 2.2 × 107 to 3.76–5.87 × 106 Da. The results showed that the amino hydrolysis of low molecular weight PAM is easier than that of the high molecular weight one, while the cleavage of its carbon chain is still difficult. The molecular weights of PAM in the effluents from the two aerobic reactors (25 °C and 40 °C) were further reduced to 4.31 × 105 and 5.68 × 105 Da by the biofilm treatment, respectively. The results would be useful for the management of wastewater containing PAM.

Light-Induced Oxidation-Reduction Reactions of Photosystem II in Dichlorophenyl-dimethyl Urea (DCM U) Inhibited Thylakoids

1990 ◽  
Vol 45 (3-4) ◽  
pp. 258-264
Author(s):  
Jeff A. Nemson ◽  
Anastasios Melis
Keyword(s):  
Difference Spectrum ◽  
Thylakoid Membranes ◽  
Donor Side ◽  
Difference Spectra ◽  
Ps Ii ◽  
Oxidation Reduction ◽  
Primary Quinone Acceptor ◽  
Dimethyl Urea ◽  
Absorbance Difference ◽  
Quinone Acceptor

Abstract Illumination of thylakoid membranes in the presence of 3-(3′,4′-dichlorophenyl)-1,1-dimethyl urea (DCMU) causes the reduction of the primary quinone acceptor QA of photosystem II (PS II) and the storage of a positive charge on the donor side of the photochemical reaction center. These oxidation-reduction reactions are accompanied by characteristic changes of absorbance in the ultra-violet region of the spectrum. The PS II-related absorbance difference spectra (250 -350 nm) were compared in control and hydroxylamine-treated thylakoid membranes, and in thylakoids suspended in the presence of carbonyl cyanide-p-(trifluoromethoxy)- phenylhydrazone (FCCP). The light minus dark difference spectra were dominated by the Q-A minus QA difference spectrum. Qualitatively, the three spectra were identical in the 300 - 350 nm region, however, they showed distinct differences in the 250 - 300 nm region. The latter arose because of different contributions from the donor side of PS II in the thylakoid membrane of the three samples. The result suggested that FCCP acts as the ultimate electron donor in DCMU - poisoned chloroplasts. Therefore, the absorbance difference spectrum in the presence of FCCP reflected a contribution from the Q-A minus QA component only. Deconvolution of the absorbance difference spectra of control and hydroxylamine-treated thylakoids yielded difference spectra attributed to the oxidation of a component on the donor side of PS II. This component did not conform with the known Mn(III) → Mn(IV) transition. Rather, it indicated the oxidation of a modified form of Mn in the presence of DCMU , probably a Mn(II) → Mn(III) transition. The results are discussed in terms of the use of DCMU - poisoned thylakoid membranes in the quantitation of the primary quinone acceptor QA by spectrophotometric approaches.

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