scholarly journals The reaction of protein amino groups with methyl 5-iodopyridine-2-carboximidate. A possible general method of preparing isomorphous heavy-atom derivatives of proteins

1973 ◽  
Vol 131 (4) ◽  
pp. 625-635 ◽  
Author(s):  
Malcolm Riley ◽  
Richard N. Perham
Keyword(s):  
Heavy Atom ◽  
Performic Acid ◽  
Amino Groups ◽  
Model Compounds ◽  
Heavy Atoms ◽  
Mild Conditions ◽  
Tryptic Cleavage ◽  
Lysine Residues ◽  
Derivatives Of ◽  
General Method

1. The synthesis of methyl 5-iodopyridine-2-carboximidate and its reaction with amino groups of model compounds and performic acid-oxidized insulin are described. The reagent was designed to introduce heavy atoms into specific sites in proteins. 2. Specific reaction with the amino groups of oxidized insulin can be achieved under reasonably mild conditions giving rise to the corresponding N-monosubstituted amidines. 3. The extent of reaction of this reagent with protein amino groups can be readily determined by difference spectroscopy. Modification of lysine residues inhibits tryptic cleavage at such residues, and this can be of assistance in establishing the site of modification in the primary structure. 4. Evidence is presented to show that methyl 5-iodopyridine-2-carboximidate can react specifically, at pH5.0, with the aromatic amino group of 3-amino-l-tyrosine; the final product of this reaction is a 2-arylbenzoxazole. 5. The use of this reagent as a general method for preparing heavy-atom isomorphous derivatives of proteins is discussed.

Syntheses of Enantiomeric N-(3-Hydroxy-2-phosphonomethoxypropyl) Derivatives of Purine and Pyrimidine Bases

1993 ◽  
Vol 58 (3) ◽  
pp. 649-674 ◽  
Author(s):  
Antonín Holý
Keyword(s):  
Benzoyl Chloride ◽  
Sodium Hydride ◽  
Cesium Carbonate ◽  
Amino Groups ◽  
Heterocyclic Base ◽  
Pyrimidine Bases ◽  
Derivatives Of ◽  
General Method

Methods of preparation of N-(3-hydroxy-2-phosphonomethoxypropyl) (HPMP) derivatives of (2S)- and (2R)-configuration (compounds I and XXVII, respectively) are described. The general method starts from the corresponding N-(2,3-dihydroxypropyl) derivatives which were converted either into the (R)-enantiomers XIII by reaction of the base with (R)-glycidol butyrate (XII) in the presence of cesium carbonate and subsequent methanolysis, or into the (S)-enantiomers XI by alkylation of the base with (R)-2,2-dimethyl-4-tosyloxymethyl-1,3-dioxolane (V) in the presence of the same reagent. The amino groups on the heterocyclic base in compounds XI and XIII were benzoylated by silylation followed by reaction with benzoyl chloride and the obtained N-benzoates XV and XVII on reaction with trityl chloride afforded the corresponding 3'-O-trityl derivatives XVI and XVIII. These compounds were condensed with bis(2-propyl) p-sulfonyloxymethylphosphonate (XXIII) in dimethylformamide in the presence of sodium hydride to give the fully protected diesters XXIV and XXVIII. These compounds could be selectively acid-hydrolyzed to remove the trityl group only under formation of compounds XXXV, or methanolyzed and then acid-hydrolyzed to remove the trityl and N-benzoyl groups and lead to compounds XXVI and XXX, or treated with bromotrimethylsilane to remove the trityl and 2-propyl group to give phosphonates of the type XXXI. All the three types of compounds were then converted into free phosphonates of the (S)-series (I) and the (R)-series (XXVII). Derivatives of cytosine (Ia, XXVIIa), adenine (Ib, XXVIIb), 2,6-diaminopurine (Ic, XXVIIc) and guanine (Id, XXVIId) were prepared. Condensation of the partially blocked adenine deriavtive XXXV with the tosyl derivative XXIII and subsequent deprotection afforded 9-(S)-(2,3-diphosphonomethoxy propyl)adenine (XLIII). Reaction of the same compound XXXV or its (R)-enantiomer XXXVIII with diethyl phosphonate , followed by deblocking, afforded 3'-O-phosphoryl derivatives (S)-HPMPA (XXXVII) and (R)-HPMPA (XL).

Dna-Binding Compounds. IV. Synthesis and Solution Conformation of a Novel Macrocyle Formed by Coupling of the Side-Chains of Adjacent L-Lysine Residues

1991 ◽  
Vol 44 (11) ◽  
pp. 1649 ◽  
Author(s):  
AM Bray ◽  
DP Kelly ◽  
TK Lim
Keyword(s):  
Carboxylic Acid ◽  
Dimethyl Sulfoxide ◽  
The Novel ◽  
Two Dimensional ◽  
Amino Groups ◽  
Solution Conformation ◽  
Mild Conditions ◽  
Dimethyl Sulfoxide Solution ◽  
Acid Methyl ◽  
Lysine Residues

The novel macrocyclic dilysine derivatives (8S,11S)-11-t-butoxycarbonylamino-2,10-dioxo-1,3,9-triazacyclopentadecane-8-carboxylic acid methyl (5) and t-butyl (6) esters were prepared by coupling of the є-amino groups of adjacent lysine residues of the esters of Boc-Lys-Lys-OR with 1,1′-carbonyldiimidazole under mild conditions. The conformation of (6) in dimethyl sulfoxide solution was determined by the use of a variety of one- and two-dimensional n.m.r. techniques.

Action of some luteinizing hormone derivatives in ovaries from pseudopregnant rats: dissimilarities between their activities on this organ and on Leydig cells

1983 ◽  
Vol 96 (3) ◽  
pp. 365-372 ◽  
Author(s):  
M.P. de la Llosa-Hermier ◽  
C. Tertrin-Clary ◽  
M. Evrard-Hérouard ◽  
C. Hermier ◽  
P. de la Llosa
Keyword(s):  
Leydig Cells ◽  
Biological Activities ◽  
Inhibition Activity ◽  
Amino Groups ◽  
Α Subunit ◽  
Binding Inhibition ◽  
Lysine Residues ◽  
Derivatives Of ◽  
Isolated Rat ◽  
Good Agreement

Biological activities of several derivatives of ovine LH obtained by chemical modification of the amino groups were investigated using ovaries from pseudopregnant rats. Binding-inhibition activities and steroidogenic potencies of ethylated, isopropylated and guanidinated LH were in good agreement, whereas adenylate cyclase activities were relatively greater. When compared with previous results on binding-inhibition activities and steroidogenic potencies using isolated rat Leydig cells, the ovaries from pseudopregnant rats appeared to be more discriminating. Ethylated and isopropylated derivatives exhibited lower binding-inhibition activities and steroidogenic potencies in female gonads. This difference was particularly evident in the case of guanidinated LH which exhibited a very low binding-inhibition activity and consequently was unable to act as an inhibitor of the action of LH on the ovaries. Guanidinated porcine LH (in which all the lysine residues of the α-subunit were transformed into homoarginine, without modification of the β-subunit which does not contain lysine) showed similar biological activities to guanidinated ovine LH in the isolated Leydig cells as well as in pseudopregnant ovaries. It can, consequently, act as an inhibitor of LH action on Leydig cells but not on the ovary of the pseudopregnant rat. Thus, the inhibitory properties of this derivative can be ascribed to the modification introduced in the α-subunit.

Heavy Atom Cluster Labeling of Biological Specimens

1985 ◽  
Vol 43 ◽  
pp. 718-719
Author(s):  
J.J. Lipka ◽  
J.F. Hainfeld ◽  
J.S. Wall
Keyword(s):  
Heavy Metal ◽  
Heavy Atom ◽  
Carbon Films ◽  
Cluster Labeling ◽  
Heavy Atoms ◽  
Glycoprotein Complex ◽  
Thin Carbon ◽  
Lysine Residues ◽  
Cluster Ion ◽  
Beam Dose

The Brookhaven STEM is capable of resolving single heavy atoms deposited on thin carbon films with a beam dose > 103 el Å-2 Single heavy atoms, therefore, are unsuitable as fiducial markers on unordered biological specimens because of the high beam dose required for direct visualization. Heavy metal-clusters or heavy metal-containing complexes have been resolved at much lower beam doses, as low as 30 el Å-2, and therefore may be useful as directly visible labels.The polyamine undecagold (11-Au) cluster ion, [(p-H2NCH2C6H4)3P]7 Au113+, has been used to covalently label the carbohydrate sites of the glycoprotein complex of human haptoglobin hemoglobin (Hp˙Hb) by a route which should be general for any glycoprotein with oxidizable carbohydrate residues. Proteins with reactive lysine residues have been covalently 11-Au labeled by the reactions noted in Scheme 1.

scholarly journals Identification of glycation at the N-terminus of albumin by gas chromatography-mass spectrometry

1989 ◽  
Vol 261 (3) ◽  
pp. 871-878 ◽  
Author(s):  
D A Robb ◽  
O S Olufemi ◽  
D A Williams ◽  
J M Midgley
Keyword(s):  
Aspartic Acid ◽  
Human Albumin ◽  
Gas Chromatography Mass Spectrometry ◽  
Amino Groups ◽  
Model Compounds ◽  
Fragment Ions ◽  
N Terminus ◽  
Lysine Residues ◽  
Characteristic Fragment

Amino groups in human albumin are modified in vivo by glucose in a non-enzymic reaction, and previous studies have implicated lysine residues as exclusive participants. An investigation using g.c.-m.s. was undertaken to ascertain whether or not the N-terminus was also involved. Appropriate model compounds [N-(1-deoxyglucitol-1-yl) and N-(1-deoxymannitol-1-yl) adducts of aspartic acid] were synthesized and the diagnostic fragment ions of suitable derivatives were established under electron-impact and negative-chemical-ionization conditions. Characteristic fragment ions were identical with those obtained from the model compounds in the mass spectra of derivatives prepared from hydrolysates of reduced albumin. A purified mixture of the model compounds was also obtained from such hydrolysates. Use of radioisotopic incorporation demonstrated that the relative extent of glycation of the epsilon-amino and alpha-amino groups in albumin was approx. 8:1. N-1-Deoxyhexitol adducts of aspartic acid were also identified in reduced and hydrolysed peptides of human urine.

A Base Specific Single Heavy Atom Stain for Electron Microscopy

1972 ◽  
Vol 30 ◽  
pp. 184-185
Author(s):  
J. P. Langmore ◽  
N. R. Cozzarelli ◽  
A. V. Crewe
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
Elastic Scattering ◽  
Heavy Atom ◽  
High Vacuum ◽  
Heavy Atoms ◽  
Large Movement ◽  
Base Sequencing ◽  
Scanning Electron

A system has been developed to allow highly specific derivatization of the thymine bases of DNA with mercurial compounds wich should be visible in the high resolution scanning electron microscope. Three problems must be completely solved before this staining system will be useful for base sequencing by electron microscopy: 1) the staining must be shown to be highly specific for one base, 2) the stained DNA must remain intact in a high vacuum on a thin support film suitable for microscopy, 3) the arrangement of heavy atoms on the DNA must be determined by the elastic scattering of electrons in the microscope without loss or large movement of heavy atoms.

The Action of Thrombin on Modified Fibrinogen

1983 ◽  
Vol 49 (03) ◽  
pp. 208-213
Author(s):  
A J Osbahr
Keyword(s):  
Physical Properties ◽  
Negative Charge ◽  
Lysine Residue ◽  
Fibrinopeptide A ◽  
Amino Groups ◽  
Lysine Residues ◽  
Citraconic Anhydride

SummaryThe modification of canine fibrinogen with citraconic anhydride modified the ε-amino groups of the fibrinogen and at the same time generated additional negative charges into the protein. The addition of thrombin to the modified fibrinogen did not induce polymerization; however, the fibrinopeptide was released at a faster rate than from the unmodified fibrinogen. The physical properties of the citraconylated fibrinogen were markedly altered by the modification of 50-60 lysine residues in one hour. A modified fibrinopeptide-A was released by thrombin from the modified fibrinogen and was electrophoretically more anionic than the unmodified fibrinopeptide-A. Edman analysis confirmed the modification of the lysine residue present in the peptide. The rate of removal of citraconylated fibrinopeptide-A from modified fibrinogen by thrombin was 30 to 40 percent greater than the cleavage of unmodified fibrinopeptide-A from unmodified fibrinogen. However, the modification of 60 or more lysine residues in the fibrinogen produced a decrease in the rate of cleavage of citraconylated fibrinopeptide-A. The results suggest that additional negative charge in the vicinity of the attachment of fibrinopeptide-A to canine fibrinogen aids in the removal of the peptide by thrombin.

Insights into the electrochemical degradation of phenolic lignin model compounds in protic ionic liquid-water system

2021 ◽  
Author(s):  
Guangyong Liu ◽  
Qian Wang ◽  
Dongxia Yan ◽  
Yaqin Zhang ◽  
Chenlu Wang ◽  
...  
Keyword(s):  
Water System ◽  
Value Added ◽  
Electrochemical Degradation ◽  
Aryl Ether ◽  
Model Compounds ◽  
Protic Ionic Liquid ◽  
Lignin Model Compounds ◽  
Mild Conditions ◽  
System P ◽  
Lignin Model

Cleavage of aryl ether (Caryl-O) bonds is crucial for conversion and value-added utilization of lignin and its derivatives, but remains extremely challenging under mild conditions due to strong Caryl-O linkages....

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