Solution Of L-proline Research Articles

Swelling of the Müller fibers in the chicken retina.

A high potassium concentration (33 meq) in the solution superfusing the isolated chicken retina causes an increase in the tissue transparency. An L-glutamate (1 mM) or L-proline (10 mM) solution has the same effect. Swelling of the Müller fibers, which have a radial position in the retina, could explain the transparency increase. This possibility was investigated in electron micrographs of retinas subjected to these treatments and fixed by freeze-substitution to preserve the water distribution in the tissue. The Müller fibers in the controls had a mean diameter of 0.22 micrometer. The fibers in retinas bathed for 2 min in the high [K+] solution were more than three times as thick (0.74 micrometer); the fibers in glutamate-treated retinas were more than twice as thick (0.49 micrometer). The fibers in the proline-treated retinas had a diameter of 0.39 micrometer. The glutamate- and proline-induced swelling may be due to a K+ release from neuronal elements, acting on the Müller fibers. The fiber swelling was postulated to be the expression of different Donnan equilibriums of fibers bathed in solutions of different K+ concentrations. The observed swelling caused by the high [K+] solution was compared with the theoretical swelling of the fiber as an ideal Donnan system, postulating permeabilities for different ions of the fiber membrane. This suggested that the high [K+] solution causes an increase in Na+ permeability in addition to the permeability of the membrane for K+, Cl-, and HCO3-. Chemical fixation with glutaraldehyde and formaldehyde in an Na-phosphate buffer yielded micrographs in which the Müller fibers of retinas treated with a high [K+] or a glutamate solution had diameters similar to those of the control preparations.

Paramagnetic ion binding to amino acids, structural and dynamical information on a Mn(II) complex of L-proline from 13C relaxation data

The 13C relaxation times (T 1 and T 2) and isotropic contact shift (Δω) of 1.28 molar aqueous solutions of L-Proline at pH = 11 (or pD = 11.4) containing 10 −4 - 10 −5 M manganese perchlorate are measured at 62.86 MHz over a temperature range of 28–80°C. Under these conditions, the Mn 2+ cation is bound to three L-Proline molecules in their dibasic form, and a fast exchange is occurring between bound and bulk L-Proline molecules. The longitudinal relaxation of carbons α, β, γ, δ of L-Proline molecules in this complex is shown to be purely dipolar, and is controlled by the rotational reorientation of the complex. The transverse relaxation of bound L-Proline molecules is mainly scalar and is controlled by the electronic relaxation. Overall relaxation rates and paramagnetic shifts also depend on the ligand exchange rate k M (from bound to free sites) at lower temperatures. The measurement of these quantities allow us to determine (i) the structure of the complex: the Mn(II) cation may be positioned with respect to each proline ligand, the sites of coordination are the unchanged nitrogen and one carboxylic atom, the distance to the Mn 2+ cation are respectively 2.08 and 1.97 Å; (ii) Hyperfine coupling constants: A= + 0.16; 0.08; 0.25 and 0.22 MHz for carbons α, β, γ, δ, respectively. (iii) Electronic relaxation parameters: assuming that T 1e ( = 2.18 x 10 −8 s at 25°C) is controlled by the modulation of the quadratic crystalline zero-field splitting interaction allows us to estimate the trace of the corresponding tensor: Δ = 0.0305 cm −1, and a correlation time τν(25°C) = 1.32 ps for the impact of solvent molecules against the Mn 2+-L-Proline complex (iv) Kinetic parameters for ligand exchange: k M(25°C) = 7.41 x 10 4s −1; ΔH ‡ = 15.6 kcal.mol. −1; ΔS ‡ = 16.1 e.u.

ChemInform Abstract: STUDIES ON SPIN‐TRAPPED RADICALS IN Γ‐IRRADIATED AQUEOUS SOLUTIONS OF L‐PROLINE AND TRANS‐4‐HYDROXY‐L‐PROLINE BY HIGH‐PERFORMANCE LIQUID CHROMATOGRAPHY AND ESR SPECTROSCOPY

Chemischer InformationsdienstVolume 12, Issue 18 Preparative Organic Chemistry ChemInform Abstract: STUDIES ON SPIN-TRAPPED RADICALS IN Γ-IRRADIATED AQUEOUS SOLUTIONS OF L-PROLINE AND TRANS-4-HYDROXY-L-PROLINE BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY AND ESR SPECTROSCOPY N. SUZUKI, N. SUZUKISearch for more papers by this authorK. MAKINO, K. MAKINOSearch for more papers by this authorF. MORIYA, F. MORIYASearch for more papers by this authorS. ROKUSHIKA, S. ROKUSHIKASearch for more papers by this authorH. HATANO, H. HATANOSearch for more papers by this author N. SUZUKI, N. SUZUKISearch for more papers by this authorK. MAKINO, K. MAKINOSearch for more papers by this authorF. MORIYA, F. MORIYASearch for more papers by this authorS. ROKUSHIKA, S. ROKUSHIKASearch for more papers by this authorH. HATANO, H. HATANOSearch for more papers by this author First published: May 5, 1981 https://doi.org/10.1002/chin.198118141AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume12, Issue18May 5, 1981 RelatedInformation

Studies on spin-trapped radicals in .gamma.-irradiated aqueous solutions of L-proline and trans-4-hydroxy-L-proline by high-performance liquid chromatography and ESR spectroscopy

The short-lived radicals generated in ..gamma..-irradiated aqueous solutions of either L-proline (I) or trans-4-hydroxy-L-proline (II) were investigated by spin trapping with 2-methyl-2-nitrosopropane and subsequently by high-performance liquid chromatography combined with ESR spectroscopy. Four ESR spectra of the spin adducts could be obtained from I and two from II, which were separated individually. The stability differences between these spin adducts are discussed in relation to the structures of the adducts.

Protolysis kinetics of some amino-acids studied by the nuclear magnetic resonance spin echo technique

Proton magnetic relaxation times have been measured as a function of pH and temperature for aqueous solutions of amino-acids in the series H3[graphic omitted]—[CH2]n—Ctext-decoration:overlineO2 where n= 1, 2, 3, 5 and 7 and also for solutions of α-alanine, sarcosine, L-proline, picolinic acid and 2-pyrrolidone. The T1 values were independent of pH but T2 had a minimum value near to pH 6 at room temperature for most of the solutions studied. In many cases, a second minimum occurred close to pKal for the amino-acid. The data are analysed in terms of proton exchanges between amino groups and sites which are oxygen attached. Kinetic parameters are derived for some exchange reactions which have not previously been considered in connection with amino-acid solutions.

PHYSIOLOGY OF THE SPORULATION PROCESS IN CLOSTRIDIUM BOTULINUM. II. MATURATION OF FORESPORES.

Day, Lawrence E., (Michigan State University, East Lansing) and Ralph N. Costilow. Physiology of the sporulation process in Clostridium botulinum. II. Maturation of forespores. J. Bacteriol. 88:695-701. 1964.-Clostridium botulinum, strain 62-A, did not sporulate endotrophically, but forespores matured to refractile, heat-resistant spores when replaced in solutions containing l-alanine and l-proline, l-isoleucine and l-proline, or l-alanine and l-arginine. Solutions of l-arginine or l-citrulline would not support the maturation process. Acetate, CO(2), and delta-amino valeric acid were produced during sporulation in a replacement solution of l-alanine and l-proline, indicating the operation of the Stickland reaction. There was no large uptake of either exogenous l-alanine or acetate during this process. Similarly, there was no apparent protein or nucleic acid synthesis, since high levels of chloramphenicol, 8-azaguanine, or mitomycin C failed to inhibit, and no significant amount of P(32) was incorporated into the spore nucleic acids. Dipicolinic acid (DPA) was synthesized during forespore maturation. It is believed that these final steps in sporulation of C. botulinum require only an exogenous source of energy which can be obtained via the Stickland reaction system, and that the synthesis of DPA and other unknown materials relies primarily on endogenous substrates.

Interactions of testosterone with amino acids

The solubility of testosterone in buffered solutions of 18 l-amino acids was determined. In solutions of l-tryptophan, l-tyrosine, l-phenylalanine, l-histidine, l-arginine, and l-lysine a significant increase was obtained above that observed in buffer alone at the corresponding ionic strength. The largest effect was obtained with l-tryptophan. A slight increase in solubility was noted in solutions of l-methionine and l-proline. With the other ten amino acids no increase was noted.