scholarly journals Hydrolytic Cleavage of Pyroglutamyl-peptide Bond. V. Selective Removal of Pyroglutamic Acid from Biologically Active Pyroglutamylpeptides in High Concentrations of Aqueous Methanesulfonic Acid

2006 ◽  
Vol 54 (6) ◽  
pp. 827-831 ◽  
Author(s):  
Junko Kobayashi ◽  
Kazuhiro Ohki ◽  
Keiko Okimura ◽  
Tadashi Hashimoto ◽  
Naoki Sakura
Keyword(s):  
Methanesulfonic Acid ◽  
Peptide Bond ◽  
Pyroglutamic Acid ◽  
Selective Removal ◽  
Biologically Active ◽  
Hydrolytic Cleavage ◽  
High Concentrations

Conformation–activity relationships and the mechanism of action of penicillin

1988 ◽  
Vol 66 (11) ◽  
pp. 2733-2750 ◽  
Author(s):  
Saul Wolfe ◽  
Kiyull Yang ◽  
Maged Khalil
Keyword(s):  
Conformational Analysis ◽  
Carbonyl Group ◽  
Active Site ◽  
Global Minimum ◽  
Peptide Bond ◽  
Biologically Active ◽  
Penicillin G ◽  
Side Chain ◽  
Geometrical Parameters ◽  
Carboxyl Group

Using the MMPEN parameters of Allinger's MMP2(85) force field, a conformational analysis has been performed on four biologically active penicillins; D-ampicillin, L-α-phenoxyethylpenicillin, penicillin G, and penicillin V, and on five biologically inactive or much less active penicillins: L-ampicillin, D-α-phenoxyethylpenicillin, N-methylpenicillin G, 6α-methylpenicillin G, and bisnorpenicillin G. Antibacterial activity is found to be associated with the existence of a global minimum having a compact structure, whose convex face is accessible to a penicillin binding protein (PBP), with the C3-carboxyl group and the side-chain N-H exposed on this face. Using the MMPEP parameters of MMP2(85), a conformational analysis has been performed on phenylacetyl-D-Ala-D-Ala-O−, a peptide model of the normal substrate of a PBP. Labischinski's global minimum has been reproduced, along with structures that correspond to Tipper and Strominger's proposal that the N4—C7 bond of a penicillin corresponds to the Ala–Ala peptide bond, and to Hasan's proposal that the N4—C5 bond of penicillin corresponds to the peptide bond. For both models, conformations of the peptide related to the pseudoaxial and pseudoequatorial conformations of the thiazolidine ring of penicillin G have been examined. It is concluded that penicillin is not a structural analog of the global minimum of the peptide; however, comparisons based on unbound conformations of PBP substrates are unable to determine which model is more appropriate, or which conformation of penicillin G is the biologically significant one. Using the ECEPP/MMPEP strategy, a model of the active site of a PBP has been obtained, following a search of 200,000 structures of the peptide Ac-NH-Val-Gly-Ser-Val-Thr-Lys-NH-Me. This peptide contains the sequence at the active site of a PBP of Streptomyces R61, for which it is also known that the C3-carboxyl group of penicillin binds to the ε-amino group of lysine, and the β-lactam reacts chemically with the serine OH. The lysine and serine side chains and the C-terminal carbonyl group are found to occupy the concave face of the active site model.A strategy for the docking of penicillins or peptides to this model, with full minimization of the conformational energies of the complexes, has been devised. All active penicillins bind through strong hydrogen bonds to the C3-carboxyl group and the side-chain N-H, and with a four-centered relationship between the O-H of serine and the (O)C-N of the β-lactam ring. The geometrical parameters of this relationship are reminiscent of those found in the gas phase transition state of neutral hydration of a carbonyl group. When the energies of formation and geometries of the pseudoaxial and pseudoequatorial penicillin G complexes are examined, there is now a clear preference for the binding of the pseudoaxial conformation, which is the global minimum of the uncomplexed penicillin in this case. A similar examination of the peptide complexes reveals that only the conformation of the peptide that corresponds to Tipper and Strominger's model, and is based on the pseudoaxial conformation of penicillin G, can form a complex with a geometry and energy comparable to those of a biologically active penicillin.

Effects of the Non-protein Amino Acids L-Canavanine and L-Canaline on the Nervous System of the Moth Manduca Sexta (L.)

1978 ◽  
Vol 75 (1) ◽  
pp. 123-132
Author(s):  
ANN E. KAMMER ◽  
D. L. DAHLMAN ◽  
GERALD A. ROSENTHAL
Keyword(s):  
Nervous System ◽  
Manduca Sexta ◽  
Biologically Active ◽  
Muscle Fibres ◽  
Time Interval ◽  
Hydrolytic Cleavage ◽  
Fresh Weight ◽  
Naturally Occurring ◽  
The Central Nervous System ◽  
Protein Amino Acids

Injection of L-canavanine, a naturally occurring arginine analogue, and of its metabolic derivative, L-canaline, induced almost continuous motor activity in adult tobacco hornworms, Manduca sexta (L.). Initially the moths flew normally, but after a time interval that depended both on the amino acid and on the dose (1-l45/μmol/g fresh weight) the moths became disorientated and muscle activity was less patterned. Canaline produced its initial effects 12-30 min after injection, whereas activity in response to canavanine began after a delay of 1-2 h. Canaline (derived from canavanine by an arginase-mediated hydrolytic cleavage) is probably the biologically active factor. Canaline did not affect axonal conduction of action potentials nor the activity of mechanoreceptors on the forewing. Canaline (22μmol/g fresh weight) prolonged the postsynaptic potential of flight muscle fibres, but after 20-40 min. the electrical activity of muscle fibres was normal. The results show that canaline alters the activity of the central nervous system of adult M. sexta, but its mode of action is unknown.

scholarly journals Geochemistry of strontium in fresh underground waters of the Sredneobskoy basin (Tomsk region, Russia)

2019 ◽  
Vol 98 ◽  
pp. 01024
Author(s):  
Irina Ivanova
Keyword(s):  
Chemical Composition ◽  
Upper Cretaceous ◽  
Biologically Active ◽  
Strontium Content ◽  
Rock Interaction ◽  
Underground Waters ◽  
Tomsk Region ◽  
Resident Time ◽  
High Concentrations ◽  
Water Rock Interaction

In the central part of Western Siberia a study of the chemical composition of fresh underground waters in the upper 600 m of the Sredneobskoy artesian basin was carried out. It was shown that underground waters generally contain high concentrations of strontium. The minimum concentrations of Sr are typical for Neogene-Quaternary sediments (600 µg/L), maximum values in the waters of the Upper Cretaceous sediments (more than 1300 µg/L). The study of strontium accumulation mechanisms in drinking underground waters is undoubtedly an important issue, as strontium is a biologically active element. Especially dangerous is the consumption of underground waters with a calcium-strontium ratio less than 100, that is the hydrogeochemical precondition for Urov endemic (Kashin-Beck disease). According to the calcium/strontium ratios data waters of the Neogene-Quaternary and Paleogene sediments selected in the south-western part of the Tomsk region are unsuitable for drinking water supply. Underground waters are shown to be in equilibrium with Al and Fe hydroxides; Ca, Mg, Fe carbonates; and clay minerals, including ferruginous. Increased strontium content in aquifers is determined not only by the chemical composition of the water-bearing rocks, but also increasing resident time of water rock interaction.

Bimodal Effect of Amphiphilic Biocide Concentrations on Fluidity of Lipid Membranes

1996 ◽  
Vol 51 (11-12) ◽  
pp. 853-858 ◽  
Author(s):  
Marian Podolak ◽  
Dariusz Man ◽  
Stanislaw Waga ◽  
Stanislaw Przestalski
Keyword(s):  
Binding Energy ◽  
Lipid Membranes ◽  
Positive Charge ◽  
Egg Yolk ◽  
Biologically Active ◽  
Double Positive ◽  
Dipole System ◽  
Monovalent Ions ◽  
Single Positive ◽  
High Concentrations

Abstract Using the spin label method (ESR) it has been shown that biologically active, amphiphilic compounds (quaternary ammonium salts -AS) containing polar heads with single and double positive charge caused, at low concentrations, decrease fluidity of liposome membranes formed with egg yolk lecithin (EYL). At higher concentrations an increase in fluidity was observed. With compounds having a single positive charge minimum fluidity of membrane structure occurs in the range of 1 to 3%, with compounds containing double positive charge -in the range of 4 -6 % . That effect does not depend on polar head size and length of alkyl chains of the AS used. Analysis of the electrostatic interaction between positive charges and dipole system suggest that at low ion concentrations the binding energy of the system increases, while it decreases at high concentrations. For the model presented, maxi­mum of binding energy of the system occurs at 3% of positive monovalent ions and at 6% of positive divalent ions admixed.

Ceramic Immobilization Options for Technetium

MRS Advances ◽  
2017 ◽  
Vol 2 (13) ◽  
pp. 753-758 ◽  
Author(s):  
Martin C. Stennett ◽  
Tae-Hyuk Lee ◽  
Daniel J. Bailey ◽  
Erik V. Johnstone ◽  
Jong Heo ◽  
...  
Keyword(s):  
Spent Nuclear Fuel ◽  
Thermo Gravimetric Analysis ◽  
Fission Products ◽  
High Mobility ◽  
Biologically Active ◽  
Purex Process ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Exchange Processes ◽  
High Concentrations

ABSTRACTLong half-life biologically active fission products, such as technetium-99, present particular problems for the disposal of spent nuclear fuel (SNF). Technetium is present in relatively high concentrations in fuel (approx. 1kg tonne-1 SNF) and has very high mobility in oxidizing environments. Technetium is therefore generally removed from SNF either by solvent extraction and reduction, during the PUREX process, or by sorption via ion exchange processes. Historically technetium has been disposed of via dilution and dispersion in the sea but stringent regulations now mean that the preferred long term option is immobilization in a highly stable and durable matrix. In this contribution we have looked at the synthesis of fluorite derivative crystalline host phases based on the zirconolite structure. Samples have been characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), thermo-gravimetric analysis (TG), and mass spectroscopy (MS). We have used Mo as an inactive surrogate for Tc.

scholarly journals Human seminal plasma contains somatostatin-64

1994 ◽  
Vol 303 (1) ◽  
pp. 263-268 ◽  
Author(s):  
L Odum ◽  
A H Johnsen
Keyword(s):  
Seminal Plasma ◽  
Biologically Active ◽  
Gel Chromatography ◽  
Human Seminal Plasma ◽  
Active Peptides ◽  
Accessory Sex Glands ◽  
Biologically Active Peptides ◽  
Terminal Amino ◽  
High Concentrations ◽  
Normal Men

Prosomatostatin is processed into two biologically active peptides, somatostatin (SS)-14 and SS-28. SS-14 is found in many tissues, whereas SS-28 is most prominent in the intestine. Human seminal plasma contained high concentrations (median = 3 nmol/l, range 0.6-76 nmol/l, n = 17) of SS with a higher M(r) than that of SS-28 as determined by gel chromatography. After isolation the SS immunoreactivity was identified as SS-64 based on the N-terminal amino acid sequence Leu-Ala-Glu-Leu-Leu-Ser-Glu-Pro-Asn-Gln-, and M(r) of 7242 determined by m.s. and on reactivity with two antibodies raised against SS-14. SS-64 displaced the binding of [125I-Tyr1]SS-14 to rat cerebrocortical membranes as effectively as SS-14 (IC50 = 1.6 mol/l). The concentration of SS-64 in seminal plasma from vasectomized men was significant higher (P < 0.005) than in normal men (median = 25.4 nmol/l, range 1.5-156 nmol/l, n = 21), suggesting that the synthesis of SS-64 takes place in the male accessory sex glands.

scholarly journals EXPERIMENTAL STUDIES OF BIOCHEMICAL GAS TREATMENT IN THE WORKING AREA OF CLOSED WASTEWATER TREATMENT PLANTS

2021 ◽  
Vol 112 ◽  
pp. 25-28
Author(s):  
V.Yu. Belousova ◽  
◽  
N.V. Kondakova ◽  
S.N. Reznikova ◽  
N.S. Serpokrilov ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Sulfur Dioxide ◽  
Wastewater Treatment Plants ◽  
Experimental Studies ◽  
Filter Material ◽  
Biologically Active ◽  
Technological Parameters ◽  
Biochemical Purification ◽  
Gas Treatment ◽  
High Concentrations

The results of the study of gas emissions from blocked wastewater treatment plants are presented. During the experiment, high concentrations of sulfur dioxide were detected. The analysis of methods for reducing the concentration of pollutants in the air of the working area of the aeration station was carried out. It is proposed to use a biochemical purification using a biofilter with a load of bark and biohumus. A model of the installation was constructed. To determine the technological parameters of the biofilter considered different types of combinations (height, moisture, particle size) of the carrier biomass and supporting layer of gravel, the effective processing time of the gas mixture. A decrease in sulfur dioxide, hydrogen sulfide, and formaldehyde was found. Additional advantages of the applied biologically active filter material are given.

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