scholarly journals Studies on vision. The nature of the retinal–opsin linkage

1968 ◽  
Vol 110 (4) ◽  
pp. 693-702 ◽  
Author(s):  
M Akhtar ◽  
P. T. Blosse ◽  
P. B. Dewhurst
Keyword(s):  
Amino Acids ◽  
Charge Transfer ◽  
Sodium Borohydride ◽  
Active Site ◽  
Spectroscopic Properties ◽  
Amino Group ◽  
Irreversible Binding ◽  
A Charge ◽  
Suitable Group ◽  
Derivatives Of

1. Convenient methods for the preparation of tritiated 11-cis-retinol, 11-cis-retinal and rhodopsin are described. Irradiation of labelled rhodopsin in the presence of sodium borohydride resulted in the irreversible binding of the retinyl moiety to the active site. Degradative studies established that the retinyl moiety in this reduced derivative of rhodopsin was attached to the ∈-amino group of lysine. In connexion with this investigation the synthesis of a number of N-retinylidene- and N-retinyl-amino acids was achieved. Derivatives of lysine with the retinyl moiety attached either to the α-amino group or to the ∈-amino group were also synthesized and characterized. 2. It is suggested that the involvement of a charge-transfer interaction between the retinylidene chromophore and a suitable group −X or −X·H on the opsin best explains the spectroscopic properties of rhodopsin and other visual proteins.

N-DICHLOROACETYL DERIVATIVES OF SERINE AND THREONINE AND OF THEIR ESTERS AND SODIUM SALTS

1960 ◽  
Vol 38 (7) ◽  
pp. 1135-1140 ◽  
Author(s):  
I. Levi ◽  
A. E. Koller ◽  
G. Laflamme ◽  
J. W. R. Weed
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Antitumor Activity ◽  
Amino Acid Ester ◽  
Amino Group ◽  
Sodium Salts ◽  
Sarcoma 37 ◽  
Walker Carcinoma ◽  
Derivatives Of ◽  
Dichloroacetyl Chloride

The N-dichloroacetyl derivatives of DL-serine and DL-threonine were prepared by the Schotten–Baumann reaction from the amino acids and dichloroacetyl chloride. Negative ninhydrin tests coupled with elementary analyses indicated that only the amino group was acylated. The ester derivatives of these compounds were prepared either by esterification of the N-dichloroacetyl-DL-amino acid with diazomethane or by the reaction of the amino acid ester with dichloroacetyl chloride in the presence of triethylamine. The sodium salts and the esters were tested for antitumor activity against sarcoma 37 in mice and Walker carcinoma 256 in rats. In both cases regression of the tumors was obtained.

scholarly journals Cytogenetic analysis of the action of carcinogens and tumour inhibitors in Drosophila melanogaster VI. The Mutagenic cell Stage Response of the Male Germ Line to the ‘Nitrogen-Mustard’ Derivatives of Amino-acids, Carboxylic acids and amines

1960 ◽  
Vol 1 (2) ◽  
pp. 173-188 ◽  
Author(s):  
O. G. Fahmy ◽  
Myrtle J. Fahmy
Keyword(s):  
Amino Acids ◽  
Nitrogen Mustard ◽  
Germ Line ◽  
Amino Group ◽  
Maximal Effect ◽  
Male Germ Line ◽  
Cell Stage ◽  
Early Spermatid ◽  
Differential Cell ◽  
Derivatives Of

The analysis of the variation in the mutation rate in the fractionated progeny of treated males, revealed a marked differential cell stage response to the various chemical series investigated. The mustard derivatives of amino-acids (particularly L-phenylalanine) exert their minimal mutagenicity on mature sperm, but possess an appreciable activity on other stages of spermatogenesis, including spermatogonia. The carboxylic-acid mustards produce their maximal effect on an early spermatid, but are practically ineffective on spermatocytes and spermatogonia. The amine mustard corresponding to the phenylalanine derivative is effective on the stages of spermiogenesis (including the early spermatids) as well as on the spermatocytes, but is inactive on the spermatogonia (at least the primary stages). The response of the gonia, therefore, is a function of the amino-acid moeity of the mutagen, and is not merely due to the presence of an amino-group in the molecule.

scholarly journals A convenient synthesis of labelled rhodopsin and studies on its active site

1970 ◽  
Vol 119 (3) ◽  
pp. 359-366 ◽  
Author(s):  
M. D. Hirtenstein ◽  
M. Akhtar
Keyword(s):  
Conformational Change ◽  
Sodium Borohydride ◽  
Active Site ◽  
Cetyltrimethylammonium Bromide ◽  
Chemical Reactivity ◽  
Amino Group ◽  
Polar Environment ◽  
Convenient Synthesis ◽  
First Time ◽  
Native Site

Digitonin solutions of labelled rhodopsin, containing 3H in the retinyl moiety, were prepared by two related methods. Labelled rhodopsin was also prepared for the first time in cetyltrimethylammonium bromide and purified by column chromatography. It was shown that only certain rhodopsin preparations on denaturation in the dark and the reduction with sodium borohydride gave up to 60% of the radioactivity in a fraction characterized as N-retinylphosphatidylethanolamine. Such preparations also gave a lipid-linked retinyl moiety at the metarhodopsin-I stage, but, as expected, a protein-linked retinyl moiety at the metarhodopsin-II stage. Other preparations however, gave exclusively protein-bound radioactivity at the native-rhodopsin, metarhodopsin-I and metarhodopsin-II stages. It is therefore conceivable that the formation of N-retinylphosphatidylethanolamine is due to a non-enzymic reaction resulting from the transfer of the retinyl moiety from its native site to an amino group of a favourably oriented phospholipid molecule. The only firmly established aspect of the rhodopsin active site remains the demonstration in our previous work that at the metarhodopsin-II stage the retinyl moiety is linked to an ∈-amino group of lysine. On the basis of chemical reactivity it is argued that the light-induced conversion of rhodopsin into metarhodopsin II involves a profound conformational change resulting in the dislocation of the retinylideneiminium chromophore from a non-polar environment in rhodopsin to a polar environment in metarhodopsin II.

The chemistry of pyrrolic compounds. LIV. The chemistry of rhodins, verdins and related compounds

1984 ◽  
Vol 37 (1) ◽  
pp. 143 ◽  
Author(s):  
PS Clezy ◽  
AH Mirza ◽  
BN Ravi ◽  
LV Thuc
Keyword(s):  
Sodium Borohydride ◽  
Secondary Alcohol ◽  
Spectroscopic Properties ◽  
Aerobic Conditions ◽  
Derivatives Of ◽  
Related Compounds

Coprorhodin II trimethyl ester has been prepared and its chemical and spectroscopic properties examined. Autoxidation of coprorhodin yields coproverdin while reduction with sodium borohydride affords a secondary alcohol which readily dehydrates under aerobic conditions to furnish a benzo-chlorin. The chemistry of these derivatives of coprorhodin has been studied.

scholarly journals Aromatic Amines in Organic Synthesis. Part II. p-Aminocinnamaldehydes

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4360
Author(s):  
Marek Pietrzak ◽  
Beata Jędrzejewska
Keyword(s):  
Organic Synthesis ◽  
13C Nmr ◽  
Aromatic Amines ◽  
Chemical Structure ◽  
Spectroscopic Properties ◽  
Spectroscopic Methods ◽  
Amino Group ◽  
The One ◽  
Ir Spectroscopic ◽  
Derivatives Of

Ten derivatives of p-aminocinnamic aldehydes were prepared from the reaction of either aromatic amines with dimethylaminoacrolein or benzaldehydes with acetaldehyde. Their chemical structure and purity were verified by 1H NMR, 13C NMR and IR spectroscopic methods. We found that the synthesis applying dimethylaminoacrolein as the reagent gets better yields than the one based on the reaction with acetaldehyde. The yields of the cinnamic aldehydes varied according to the type of the amino group and the number and position of the substituents. The basic spectroscopic properties of the p-aminocinnamic aldehydes are also described since the compounds may be a precursor for the synthesis of dyes for diverse applications, e.g., in medicine and optoelectronics.

The Reaction of Aminoacylase with Chloromethylketone Analogs of Amino Acids

1977 ◽  
Vol 32 (9-10) ◽  
pp. 769-776 ◽  
Author(s):  
Jürgen Frey ◽  
Werner Kordel ◽  
Friedhelm Schneider
Keyword(s):  
Amino Acids ◽  
Aspartic Acid ◽  
Active Site ◽  
Lysine Residue ◽  
Amino Group ◽  
Sh Groups ◽  
Competitive Inhibitors ◽  
Kinetics Of ◽  
Covalently Bound

Abstract1. Aminoacylase is irreversibly inactivated by the chloromethylketone analogs of benzyloxy-carbonyl-L-alanine, L-alanine, L-leucine, L-aspartic acid (β), tosyl-L-phenylalanine and L-leucyl-L-alanine. The kinetics of the inactivation of the enzyme by the halo-methylketones were investigated.2. Leucyl-and alanyl chloromethylketone inactivate the enzyme by blocking of 4 SH groups. Experiments with [U-14C] leucyl chloromethylketone confirm that maximal 4 residues are covalently bound to the protein.3. Inactivation of the enzyme by benzyloxycarbonylalanyl and tosylphenylalanyl chloromethyl­ ketone is the result of the substitution of the £-amino group of one lysine residue per active site and not of SH groups. However, in the presence of competitive inhibitors these halomethylketones react only with the SH groups of the enzyme, too.

19F nuclear magnetic resonance studies of the interaction of inhibitors with chymotrypsin. Ring-fluorinated derivatives of N-trifluoroacetylphenylalanine

1978 ◽  
Vol 31 (10) ◽  
pp. 2179 ◽  
Author(s):  
M Tsavalos ◽  
BC Nicholson ◽  
TM Spotswood
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Active Site ◽  
Enzyme Inhibitor ◽  
Aromatic Amino Acids ◽  
Binding Parameters ◽  
Magnetic Resonance Studies ◽  
Derivatives Of

The complexes formed between chymotrypsin and the doubly fluorine- labelled inhibitors, o-, m- and p-fluoro-N-trifluoroacetyl-D- phenylalanine and 2,4-difluoro-N-trifluoroacetyl-D-phenylalanine, have been characterized by 19F N.M.R. spectroscopy and binding parameters, ΔB and KI, have been derived. The results confirm the importance of the amido binding site in orienting aromatic amino acids at the active site of chymotrypsin. Changes in ΔB, the change in chemical shift of the enzyme-bound inhibitor, are shown to be a very sensitive probe of enzyme-inhibitor interactions.

scholarly journals Analysis of the Molecular Interactions between Cytochromes P450 3A4 and 1A2 and Aflatoxins: A Docking Study

2019 ◽  
Vol 9 (12) ◽  
pp. 2467 ◽  
Author(s):  
Isui Abril García-Montoya ◽  
Norma Rosario Flores-Holguín ◽  
Linda-Lucila Landeros-Martínez ◽  
Mónica Alvarado-González ◽  
Quintín Rascón-Cruz ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Amino Acids ◽  
Molecular Docking ◽  
Charge Transfer ◽  
Active Site ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Cytochromes P450 ◽  
Docking Analysis ◽  
Molecular Docking Analysis

Mycotoxins known as aflatoxins (AF) are produced as a secondary metabolite by some species of Aspergillus fungi. They are considered carcinogenic, hepatotoxic, teratogenic, and mutagenic. In this study, the molecular structure, chemical reactivity, and charge transfer values of AFB1, B2, G1, and G2 were analyzed using density functional theory. Different methodologies—B3LYP/6-311G(d,p) and M06-2X/6-311G(d,p)—were applied for geometrical calculations. Chemical reactivity parameters were used in the calculation of charge transfer values during the interaction between protein and ligand. The binding energy, the electrostatic interactions, and the amino acids of the active site were determined by molecular docking analysis between AF and cytochromes P450 (3A4 and 1A2), employing different PDB files (CYP3A4:1TQN, 2V0M, 4NY4 and 1W0E, and CYP1A2:2HI4). Molecular docking analysis indicated that the central rings of the AF are involved in the interaction with the HEM group of the active site. The differences in the molecular structure of the AF affect their position regarding the HEM group. The resulting configurations presented considerable variation in the amino acids and the position of the coupling. The charge transfer values showed that there is oxidative damage inside the active site and that the HEM group is responsible for the main charge transferences.

Charge-Transfer Interactions of Aliphatic Amino Acids with Metal Ions

1971 ◽  
Vol 26 (11) ◽  
pp. 1098-1101 ◽  
Author(s):  
Wolfgang Lohmann
Keyword(s):  
Amino Acids ◽  
Charge Transfer ◽  
Charge Transfer Complex ◽  
Resonance Spectrum ◽  
Straight Line ◽  
Spin Resonance ◽  
A Charge ◽  
Prosthetic Groups ◽  
Good Agreement

The effect of various non-SH-containing amino acids on an electron spin resonance spectrum as well as on an optical absorption spectrum of an aqueous copper (II) solution was investigated. The data obtained indicate that a charge-transfer complex is formed with amino acids acting as electron donors. A plot of the wavelength of the CT-band vs. the pK values of the carboxyl group exhibits a straight line with the larger pK values appearing at shorter wavelengths. Similar results were obtained when the intensity was plotted vs. the pK values of the amino group; again, higher pK values correspond to lower intensities. Thus, the method allows the determination of the pK values of prosthetic groups of amino acids. The data obtained are in good agreement with the CT-theory.

Acyl-Enzymes as Thrombolytic Agents in Dog Models of Venous Thrombosis and Pulmonary Embolism

1984 ◽  
Vol 51 (02) ◽  
pp. 248-253 ◽  
Author(s):  
R J Dupe ◽  
P D English ◽  
R A G Smith ◽  
J Green
Keyword(s):  
Pulmonary Embolism ◽  
Side Effects ◽  
Venous Thrombosis ◽  
Active Site ◽  
Acute Pulmonary Embolism ◽  
Quantitative Model ◽  
Beagle Dog ◽  
Thrombosis Model ◽  
Derivatives Of

SummaryA quantitative model of venous thrombosis in the beagle dog is described. The model was adapted to permit ageing of isolated experimental clots in vivo. A model of acute pulmonary embolism in this species is also described. In the venous thrombosis model, infusion of streptokinase (SK) or SK-activated human plasmin gave significant lysis but bolus doses of SK. plasmin complex were ineffective. Active site anisoylated derivatives of SK. plasminogen complex, SK-activated plasmin and activator-free plasmin were all active when given as bolus doses in both models. At lytic doses, the acyl-enzymes caused fewer side-effects attributable to plasminaemia than the corresponding unmodified enzymes.

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