Search for regular polypeptides possessing esterase properties. I. Polypeptides containing tyrosine and glutamic acid residues

An investigation has been made of the catalytic properties in relation to the hydrolysis of p-NPA of six polypeptides of regular structure: H-[Glu-Tyr]_n-OH (1), H-[Glu₂-Tyr]_n-OH (2), H-[Glu-Tyr₃]_n-OH (3), H-[Glu₃-Tyr]_n-OH (4), H-[Glu₃-Tyr]_n-OH (5), and H-[Glu-Tyr₂]_n]-OH (6). It has been shown that polypeptides (I), (III), and (IV) catalyze the hydrolysis of p-NPA (p-nitrophenyl acetate). An enzyme-like type of catalysis has been found. Some catalytic characteristics have been calculated and the dependence of the rate of hydrolysis on the pH of the medium, the temperature, and the concentration of p-NPA have been discussed. The structures of the catalytically active and catalytically inactive polypeptides have been studied by the circular dichroism method. It has been shown that under conditions in which the catalytic properties of polypeptides are shown to the maximum degree there is a structure of the random coil type. The catalytic activity falls or disappears completely when ordered fragments of the -helix and -structure types appear in the structure. It has been found that polypeptide (I) possesses the maximum catalytic activity. It exceeds the activity of a copolymer of the same amino acids by an order of magnitude.Institute of Molecular Biology, Academy of Sciences of the USSR, Moscow. Tadzhik State University, Dushanbe. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 687–699, September, October, 1979.     

Synthesis of regular polypeptides,containing arginine residues

Conclusions Using the method of activated ethers, we synthesized the regular polypeptides: H-(Ala-Arg)_n-OH, H-(Ala-Ala-Arg)_n-OH, H-(Ala-Arg-Arg)_n-OH, and H-(Gly-Arg-Arg)_nlOH with a M_av of 1200–7000.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2596–2597, November, 1972.     

Some bactericidal properties of oligopeptides and regular polypeptides including lysine and ornithine residues

Summary Oligopeptides and polypeptides of the sequences Lys₆-, Ala-Lys₄-Ala, Lys₈-, Orn₂-Ala₂-, Lys₃-Pro-, Lys₃-Gly-, Orn₃-Gly-, Lys-Pro-, Lys-Pro₂-, Lys₂-Pro-, Lys₃-Ala- possess bactericidal properties in relation to a strain of the bacteriumStaphylococcus aureus.It has been shown that with an increase in the amount of lysine and ornithine residues in the polypeptide chain the bactericidal properties increase; proline residues play a fundamental part in the manifestation of these properties.Institute of Molecular Biology, Academy of Sciences of the USSR, Moscow. Institute of Chemistry, Academy of Sciences of Tadzhik SSR, Dushanbe. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 130–133, January–February, 1978.     

Adsorption properties of silica-based sorbents containing phosphonic acid residues

Isotherms are measured for nitrogen, n-hexane, triethylamine, and water vapor adsorption on silicas of different origins, the surface layers of which contain functional groups of the ??Si(CH₂)₂P(O)(OH)₂ composition, namely, ethylene- and phenylene-bridged polysilsesquioxane xerogels produced by the sol-gel method, silica microspheres synthesized from tetraethoxysilane in the presence of [CH₃(CH₂)₁₇N(CH₃)₃]Br as a template by spray-drying method, and SBA-15 mesoporous silica produced based on tetraethoxysilane using Pluronic 123 as a template. It is shown that all of the samples possess high specific surface areas, while the types of adsorption isotherms and the accessibility of active acidic sites for adsorption interactions with electron-donor molecules depend on the structures of pores and surface layers, which are governed by the methods of synthesis and postsynthesis sample treatment.     

Synthesis of regular polypeptides including lysine, proline, and alanine residues

Conclusions Polypeptides of the following sequences have been obtained: -Lys-Pro-,-Lys₂-Pro-, -Lys₃-Pro-,-Lys-Pro₂-, and -Lys-Ala-, with molecular weights of from 1000 to 14,000. It has been established that the use of pentachlorophenyl esters for polymerization in place of 2,4,5-trichlorophenyl esters leads to a considerable increase in the molecular weights of the polypeptides.Institute of Chemistry, Academy of Sciences of Tadzhik SSR. Institute of Molecular Biology, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 210–213, March–April, 1974.     

Synthesis of regular polypeptides including lysine,proline, and alanine residues

Summary From the epigeal part ofThermopsis alterniflora, in addition to the alkaloids found previously, argentine, argentamine, and a new alkaloid, dimethamine, which is a representative of the bimolecular series, have been isolated. The structure of 3-(3,4-dihydro-N-methylcytisin-5-yl)-N-methylcytisine has been proposed for dimethamine on the basis of IR, UV, mass, and NMR spectra and also from its conversion products.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 218–222, March–April, 1972.     

C-terminal amino acid residue loss for deprotonated peptide ions containing glutamic acid, aspartic acid, or serine residues at the C-terminus

Deprotonated peptides containing C-terminal glutamic acid, aspartic acid, or serine residues were studied by sustained off-resonance irradiation collision-induced dissociation (SORI-CID) in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer with ion production by electrospray ionization (ESI). Additional studies were performed by post source decay (PSD) in a matrix-assisted laser desorption ionization/time-of-flight (MALDI/TOF) mass spectrometer. This work included both model peptides synthesized in our laboratory and bioactive peptides with more complex sequences. During SORI-CID and PSD, [M - H]- and [M - 2H]2- underwent an unusual cleavage corresponding to the elimination of the C-terminal residue. Two mechanisms are proposed to occur. They involve nucleophilic attack on the carbonyl carbon of the adjacent residue by either the carboxylate group of the C-terminus or the side chain carboxylate group of C-terminal glutamic acid and aspartic acid residues. To confirm the proposed mechanisms, AAAAAD was labelled by 18O specifically on the side chain of the aspartic acid residue. For peptides that contain multiple C-terminal glutamic acid residues, each of these residues can be sequentially eliminated from the deprotonated ions; a driving force may be the formation of a very stable pyroglutamatic acid neutral. For peptides with multiple aspartic acid residues at the C-terminus, aspartic acid residue loss is not sequential. For peptides with multiple serine residues at the C-terminus, C-terminal residue loss is sequential; however, abundant loss of other neutral molecules also occurs. In addition, the presence of basic residues (arginine or lysine) in the sequence has no effect on C-terminal residue elimination in the negative ion mode.     

Syntheses of chiral bishomodiazacalix[4]arenes incorporating amino acid residues: Molecular recognition for racemic ammonium ions by the macrocycles possessing tyrosine residues

Chiral bishomodiazacalix[4]arenes containing amino acid residues were prepared. The ¹H and ¹³C nmr spectra indicated that the macrocycles preferably adopted a cone conformation, which suggested that the cyclophane moiety was in a chiral twisted form. Circular dichroism spectra supported the existence of the chirality of the cyclophane unit, and showed that intramolecular hydrogen bonding plays an important role in the transmission of the chirality from the amino acid residues to the cyclophane moiety. Macrocycles bearing a tyrosine residue have a π‐base cavity large enough to include the ammonium ion, and can serve as a shift reagent for the racemic ammonium ions upon complexation during a ¹H nmr analysis.     

Protein tyrosine phosphatase oligomerization studied by a combination of 15N NMR relaxation and 129Xe NMR. Effect of buffer containing arginine and glutamic acid

15N NMR relaxation and 129Xe NMR chemical shift measurements offer complementary information to study weak protein-protein interactions. They have been applied to study the oligomerization equilibrium of a low-molecular-weight protein tyrosine phosphatase in the presence of 50 mM arginine and 50 mM glutamic acid. These experimental conditions are shown to enhance specific protein-protein interactions while decreasing nonspecific aggregation. In addition, 129Xe NMR chemical shifts become selective reporters of one particular oligomer in the presence of arginine and glutamic acid, indicating that a specific Xe binding site is created in the oligomerization process. It is suggested that the multiple effects of arginine and glutamic acid are related to their effective excluded volume that favors specific protein association and the destabilization of partially unfolded forms that preferentially interact with xenon and are responsible for nonspecific protein aggregation.     

Synthesis of a hexapeptide containing valine, leucine, and glutamic acid

Summary The previously unreported methyl ester of N-benzyloxycarbonyl-L-phenylalanyl-L-valyl-O-methyl-L-glutamyl-L-leucyl-L-valyl-L-alanine has been synthesized.T. G. Shevchenko Kiev State University. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 785–788, November–December, 1975.