Isolation and identification of some photo-oxidation products of tryptophan

1971 ◽  
Vol 24 (6) ◽  
pp. 1285 ◽  
Author(s):  
WE Savige
Keyword(s):  
Aqueous Solution ◽  
Amino Acid ◽  
Methyl Ester ◽  
Visible Light ◽  
Major Product ◽  
The Other ◽  
Oxidation Products ◽  
Isolation And Identification ◽  
Photo Oxidation ◽  
Tryptophan Methyl Ester

When an aerated aqueous solution of tryptophan at pH 6-9 is irradiated by visible light in the presence of a photosensitizing dye, N?- formylkynurenine is usually a major product. However, a similar irradiation in dilute ammonia at pH 8-9 gives mainly 4-(2-amino-2- carboxyethyl)quinazoline, a new amino acid; formyl-kynurenine 1s shown not to be an intermediate in the photoreaction. Tryptophan methyl ester and 2-methyltryptophan give photoproducts analogous to those of tryptophan. On the other hand, N-acetyltryptophan and indole-3- propionic acid give the formylkynurenine analogue either in the absence or presence of ammonia, no quinazoline being detected.

scholarly journals The inhibition of glutamate dehydrogenase by l-serine O-sulphate and related compounds and by photo-oxidation in the presence of Rose Bengal

1971 ◽  
Vol 123 (3) ◽  
pp. 421-426 ◽  
Author(s):  
N. Tudball ◽  
P. Thomas
Keyword(s):  
Amino Acid ◽  
Methyl Ester ◽  
Glutamate Dehydrogenase ◽  
Rose Bengal ◽  
Amino Acid Analysis ◽  
Inhibitory Effects ◽  
Irreversible Inhibitor ◽  
Photo Oxidation ◽  
Rapid Inactivation ◽  
Related Compounds

1. Glutamate dehydrogenase was inhibited by l-serine O-sulphate, β-chloro-l-alanine, O-phospho-l-serine and β-chloro-l-alanine methyl ester. With the exception of β-chloro-l-alanine methyl ester which was an irreversible inhibitor, it was possible to reverse the inhibitory effects by dialysis. 2. Both NAD+ and glutamate afford some protection against the inhibition due to the methyl ester. No change in the normal stimulatory effect exhibited by ADP was observed in the presence of β-chloro-l-alanine methyl ester but the effect due to GTP was modified. 3. Irradiation of glutamate dehydrogenase in the presence of Rose Bengal produced rapid inactivation. Amino acid analysis of the inactivated enzyme showed that eight histidine residues had been destroyed in the process.

scholarly journals On the Involvement of Singlet Oxygen in the Biosynthesis of Oxygenation Products of the Furocoumarin Imperatorine

1984 ◽  
Vol 39 (10) ◽  
pp. 1433-1441 ◽  
Author(s):  
Nicolaas J. de Mol ◽  
Johannes Reisch ◽  
Gerardus M. J. Beijersbergen van Henegouwen
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Protective Effect ◽  
Singlet Oxygen ◽  
Oxidation Products ◽  
Photo Oxidation ◽  
Uva Light ◽  
Β Carotene

The role of singlet oxygen (1O2) in the photo-oxidation of the furocoumarin im peratorine was investigated in vitro. Irradiation with visible light and sensitization with methylene blue yielded the imperatorine oxidation product isogosferol and the corresponding ketone as main products. The involvement of 1O2 was dem onstrated by studying the rate of oxidation under conditions that affect the lifetime of 1O2. Com pared to a range of other furocoumarins, im peratorine appeared to be moderately active as a 1O2 generator. The extent of 1O2 production correlated with the skin sensitizing activity. Upon irradiation of im peratorine itself with UVA light (360 nm) no isogosferol formation is observed, probably as a consequence of its photochemical instability. Irradiation with visible light (λ > 400 nm) of a chlorophyll chromophore containing sensitizer in the presence of imperatorine, yielded isogosferol and the corresponding ketone product. This dem onstrates that in the formation of 1O2 oxidation products of imperatorine in plants naturally occuring sensitizers e.g. chlorophyll and visible light are involved, rather than 1O2 produced by im peratorine or other furocoumarins and UVA light. The protective effect on the chlorophyll sensitized im peratorine oxidation by the 1O2- and chlorophyll triplet quencher β-carotene was demonstrated in a lipophilic solvent.

LYTIC ENZYMES OF SORANGIUM SP.: A COMPARISON OF THE PROTEOLYTIC PROPERTIES OF THE α- AND β-LYTIC PROTEASES

1965 ◽  
Vol 43 (12) ◽  
pp. 1961-1970 ◽  
Author(s):  
D. R. Whitaker ◽  
C. Roy ◽  
C. S. Tsai ◽  
L. Jurášek
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Methyl Ester ◽  
Esterase Activity ◽  
The Other ◽  
Carboxyl Group ◽  
Lytic Enzymes ◽  
Amidase Activity ◽  
A Chain ◽  
Hydrolysis Of

The proteolytic properties of the α- and β-lytic proteases of a species of Sorangium were compared. Neither enzyme showed evidence of aminopeptidase, carboxypeptidase, or amidase activity in tests with a series of peptides and substituted amino acids at pH 5.2, 7.2, and 9.0. Neither enzyme showed evidence of esterase activity towards N-benzoyl-L-arginine methyl ester at pH 6.8. Hydrolysis of the A chain of oxidized insulin at pH 9 slows down markedly when the α-enzyme has cleaved the chain once; the initial fast cleavage can take place at linkages between residues 9 and 10, 10 and 11, and 12 and 13; more slowly cleaved linkages are between residues 3 and 4, and 8 and 9. Hydrolysis of the B chain by the α-enzyme at pH 9 is still faster and slows down when the chain has been cleaved twice. One fast cleavage is at the linkage between residues 18 and 19; the other can take place at the linkages between residues 12 and 13, and 14 and 15; more slowly cleaved linkages are between residues 8 and 9, 9 and 10, and 15 and 16. Under the conditions tested, the β-enzyme does not hydrolyze the A chain appreciably at pH 9. It cleaves the B chain rapidly at the linkage between residues 23 and 24 and more slowly at linkages between residues 18 and 19. The linkages split by both enzymes are those which involve the carboxyl group of a neutral amino acid.

Mechanistic studies on the formation of aminoxyl radicals from 5,5-dimethyl-1-pyrroline-N-oxide in Fenton systems. Characterization of key precursors giving rise to background ESR signals

1992 ◽  
Vol 70 (11) ◽  
pp. 2818-2827 ◽  
Author(s):  
Keisuke Makino ◽  
Akifumi Hagi ◽  
Hiroshi Ide ◽  
Akira Murakami ◽  
Masatoshi Nishi
Keyword(s):  
Aqueous Solution ◽  
Hydroxamic Acid ◽  
Spin Trap ◽  
Careful Analysis ◽  
Major Product ◽  
Oxidation Products ◽  
Fragmentation Patterns ◽  
Aminoxyl Radicals ◽  
C Nmr

To assign unidentified ESR signals obtained in a Fenton system with a spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), fundamental reactions of DMPO have been thoroughly investigated. When the concentration of Fe2+ in Fenton systems exceeded 1% of that of DMPO, background ESR signals totally distinguishable from 2-hydroxy-5,5-dimethyl-1-pyrrolidinyloxy (DMPO-OH) appeared, and simultaneously absorbance at 520 nm increased, which was characteristic of hydroxamic acids complexed with Fe3+. To prove the postulated formation of hydroxamic acid as a key intermediate, DMPO was subjected to Fenton reaction or was treated with Fe3+ in aqueous solution to produce DMPO-OH (Makino etal. Biochem. Biophys. Res. Commun. 172, 1073 (1990)), and a major product was isolated by RPLC. Based on 1H, 13C NMR and MS measurements, the structure of the major product was assigned to 1-hydroxy-5,5-di-methyl-1-pyrrolid-2-one (HDMPN) having a hydroxamic acid structure. Temperature dependence of NMR spectra and careful analysis of the fragmentation patterns in MS further revealed that HDMPN was present in equilibrium with 2-hydroxy-5,5-dimethyl-1-pyrroline-N-oxide (HDMPO), a tautomer of HDMPN. It has also been shown that the oxidation of DMPO yielding HDMPN and HDMPO occurs via DMPO-OH and is driven by Fe3+. These oxidation products (HDMPN and HDMPO) were readily converted to the corresponding ESR visible aminoxyl radicals by oxidation and •OH addition in aqueous solution, respectively, and superimposition of the ESR signals arising from these radicals accounts for the background signals observed in Fenton systems with DMPO as a spin trap.

Activity of Plasmin and Streptokinase-Activator on Substituted Arginine and Lysine Esters

1966 ◽  
Vol 16 (01/02) ◽  
pp. 018-031 ◽  
Author(s):  
S Sherry ◽  
Norma Alkjaersig ◽  
A. P Fletcher
Keyword(s):  
Molecular Structure ◽  
Methyl Ester ◽  
Comparative Studies ◽  
Esterase Activity ◽  
Methyl Esters ◽  
Hydrolytic Activity ◽  
The Other ◽  
Other Hand

SummaryComparative studies have been made of the esterase activity of plasmin and the streptokinase-activator of plasminogen on a variety of substituted arginine and lysine esters. Human plasmin preparations derived by different methods of activation (spontaneous in glycerol, trypsin, streptokinase (SK) and urokinase) are similar in their esterase activity; this suggests that the molecular structure required for such esterase activity is similar for all of these human plasmins. Bovine plasmin, on the other hand, differs from human plasmin in its activity on several of the substrates studied (e.g., the methyl esters of benzoyl arginine and tosyl, acetyl and carbobenzoxy lysine), a finding which supports the view that molecular differences exist between the two animal plasmins. The streptokinase-activator hydrolyzes both arginine and lysine esters but the ratios of hydrolytic activity are distinct from those of plasmin and of other activators of plasminogen. The use of benzoyl arginine methyl ester as a substrate for the measurement of the esterase activity of the streptokinase-activator is described.

Oxytocin analogues with non-coded amino acid residues in position 8: [8-Neopentylglycine]oxytocin and [8-cycloleucine]oxytocin

1987 ◽  
Vol 52 (9) ◽  
pp. 2317-2325 ◽  
Author(s):  
Jan Hlaváček ◽  
Jan Pospíšek ◽  
Jiřina Slaninová ◽  
Walter Y. Chan ◽  
Victor J. Hruby
Keyword(s):  
Amino Acid ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
The Other ◽  
Amino Acid Residues ◽  
Phase Synthesis ◽  
Other Hand ◽  
Fragment Condensation

[8-Neopentylglycine]oxytocin (II) and [8-cycloleucine]oxytocin (III) were prepared by a combination of solid-phase synthesis and fragment condensation. Both analogues exhibited decreased uterotonic potency in vitro, each being about 15-30% that of oxytocin. Analogue II also displayed similarly decreased uterotonic potency in vivo and galactogogic potency. On the other hand, analogue III exhibited almost the same potency as oxytocin in the uterotonic assay in vivo and in the galactogogic assay.

C-Terminal amino acid sequence of chicken pepsinogen and its homology with sequences of other acid proteases

1980 ◽  
Vol 45 (4) ◽  
pp. 1144-1154 ◽  
Author(s):  
Miroslav Baudyš ◽  
Helena Keilová ◽  
Vladimír Kostka
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
The Other ◽  
Terminal Sequence ◽  
Terminal Part ◽  
Terminal Amino Acid ◽  
Tryptic Peptides ◽  
Terminal Amino ◽  
High Degree ◽  
Terminal Amino Acid Sequence

To determine the primary structure of the C-terminal part of the molecule of chicken pepsinogen the tryptic, chymotryptic and thermolytic digest of the protein were investigated and peptides derived from this region were sought. These peptides permitted the following 21-residue C-terminal sequence to be determined: ...Ile-Arg-Glu-Tyr-Tyr-Val-Ile-Phe-Asp-Arg-Ala-Asn-Asn-Lys-Val-Gly-Leu-Ser-Pro-Leu-Ser.COOH. A comparison of this structure with the C-terminal sequential regions of the other acid proteases shows a high degree of homology between chicken pepsinogen and these proteases (e.g., the degree of homology with respect to hog pepsinogen and calf prochymosin is about 66%). Additional tryptic peptides, derived from the N-terminal part of the zymogen molecule whose amino acid sequence has been reported before, were also obtained in this study. This sequence was extended by two residues using an overlapping peptide. An ancillary result of this study was the isolation of tryptic peptides derived from other regions of the zymogen molecule.

An ESR study of the peroxidase reaction catalyzed by human methaemoglobin and methaemoglobin-haptoglobin complex

1991 ◽  
Vol 56 (4) ◽  
pp. 923-932
Author(s):  
Jana Stejskalová ◽  
Pavel Stopka ◽  
Zdeněk Pavlíček
Keyword(s):  
Hydrogen Peroxide ◽  
Ascorbic Acid ◽  
Amino Acid ◽  
Peroxidase Activity ◽  
Amino Acid Analysis ◽  
Superoxide Radical ◽  
Esr Spectra ◽  
The Other ◽  
Delocalized Electron

The ESR spectra of peroxidase systems of methaemoglobin-ascorbic acid-hydrogen peroxide and methaemoglobin-haptoglobin complex-ascorbic acid-hydrogen peroxide have been measured in the acetate buffer of pH 4.5. For the system with methaemoglobin an asymmetrical signal with g ~ 2 has been observed which is interpreted as the perpendicular region of anisotropic spectrum of superoxide radical. On the other hand, for the system with methaemoglobin-haptoglobin complex the observed signal with g ~ 2 is symmetrical and is interpreted as a signal of delocalized electron. After realization of three repeatedly induced peroxidase processes the ESR signal of the perpendicular part of anisotropic spectrum of superoxide radical is distinctly diminished, whereas the signal of delocalized electron remains practically unchanged. An amino acid analysis of methaemoglobin along with results of the ESR measurements make it possible to derive a hypothesis about the role of haptoglobin in increasing of the peroxidase activity of methaemoglobin.

Comparison of the Potency of 8-L-Arginine, 8-D-Arginine and 8-D-Homoarginine Vasopressin Analogs with Substituted Phenylalanine in Position 2

1994 ◽  
Vol 59 (6) ◽  
pp. 1439-1450 ◽  
Author(s):  
Miroslava Žertová ◽  
Jiřina Slaninová ◽  
Zdenko Procházka
Keyword(s):  
Amino Acid ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Basic Amino Acid ◽  
The Other ◽  
Side Chain ◽  
Inhibitory Potency ◽  
Phase Synthesis ◽  
Other Hand ◽  
Order Of Magnitude

An analysis of the uterotonic potencies of all analogs having substituted L- or D-tyrosine or -phenylalanine in position 2 and L-arginine, D-arginine or D-homoarginine in position 8 was made. The series of analogs already published was completed by the solid phase synthesis of ten new analogs having L- or D-Phe, L- or D-Phe(2-Et), L- or D-Phe(2,4,6-triMe) or D-Tyr(Me) in position 2 and either L- or D-arginine in position 8. All newly synthesized analogs were found to be uterotonic inhibitors. Deamination increases both the agonistic and antagonistic potency. In the case of phenylalanine analogs the change of configuration from L to D in position 2 enhances the uterotonic inhibition for more than 1 order of magnitude. The L to D change in position 8 enhances the inhibitory potency negligibly. Prolongation of the side chain of the D-basic amino acid in position 8 seems to decrease slightly the inhibitory potency if there is L-substituted amino acid in position 2. On the other hand there is a tendency to the increase of the inhibitory potency if there is D-substituted amino acid in position 2.

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