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PubMed1991

Primary structure of Kunitz-type trypsin inhibitor-2a (pI 5.9) from Psophocarpus tetragonolobus (L.) DC seed.

The primary structure of acidic trypsin inhibitor-2a (WBTI-2a, pI 5.9) from Psophocarpus tetragonolobus (L.) DC seed was determined. This inhibitor consists of a single polypeptide chain of 180 amino acids including four half-cystine residues and has an N-terminal residue of pyroglutamic acid. The sequence of WBTI-2a, pI 5.9, showed 84% identity to acidic trypsin inhibitor-2 (WBTI-2, pI 5.1) but only 57% identity to the basic trypsin inhibitor (WBTI-1, pI 8.9) and 50% identity to the chymotrypsin inhibitor of winged bean. The data indicate that winged bean seed contains a family of three Kunitz-type inhibitors which have about 50% identity.

Amino Acid Sequence↗

PubMed1992

Trypsin inhibitors from bottle gourd (Lagenaria leucantha Rusby var. Depressa Makino) seeds. Purification and amino acid sequences.

Two almost identical trypsin isoinhibitors, LLDTI-I and LLDTI-II, from bottle gourd (Lagenaria leucantha Rusby var. Depressa Makino) seeds were purified by acetone precipitation, gel filtration and reversed phase chromatography. LLDTI-I and LLDTI-II consist of 30 and 29 amino acid residues, respectively, and have identical sequences, except that LLDTI-I has one additional pyroglutamic acid residue at N-terminus. Both proteins are strong inhibitors of bovine trypsin, with Ki values of 2.4.10(-10) M (LLDTI-I) and 9.6.10(-11) M (LLDTI-II). Amino acid sequences are as follows: [sequence: see text]

Amino Acid Sequence↗

PubMed1983

End group analysis of the cytosolic and mitochondrial fumarases from rat liver.

Some molecular properties of the cytosolic and mitochondrial fumarases were compared. The carboxyl(C)-terminal amino acid of both the cytosolic and mitochondrial fumarases of rat liver cell was identified as leucine by using carboxypeptidase (CPase) A. As the amino(N)-terminal amino acid of both the cytosolic and mitochondrial fumarases could not be identified by the dansyl chloride method or by the cyanate method, the N-termini of these two fumarases seems to be masked. Both fumarases, after S-carboxymethylation, were completely digested with pronase E and CPase A and B, and the amino acids with blocked amino group were analyzed by high voltage paper electrophoresis and amino acid analysis after acid hydrolysis of these amino acid derivatives. The N-termini of the mitochondrial and cytosolic fumarases were identified as pyroglutamic acid and N-acetylalanine, respectively. To compare the primary structures of the two fumarases in detail, each fumarase was digested with an arginine-specific protease or cleaved with cyanogen bromide. The electrophoretic profiles of the digests of these fumarases were indistinguishable from each other.

Amino Acid Sequence↗

PubMed2000

Complete amino acid sequence of the protease inhibitor BWI-4a from buckwheat seeds.

The complete amino acid sequence of the protease inhibitor BWI-4a from buckwheat (Fagopyrum esculentum Moench) seeds has been established by automated Edman degradation in combination with MALDI-TOF mass spectrometry. The inhibitor molecule consists of 67 amino acid residues with a single disulfide bond. Its N-terminus is blocked by a pyroglutamic acid residue. The reactive site of the inhibitor contains an Arg43-Asp44 bond. Mass spectrometry revealed that inhibitor BWI-4a is present in buckwheat seeds in two isoforms differing by a single amino acid substitution of Gly40 for Ala40. Analysis of the amino acid sequence of the BWI-4a inhibitor indicates that this inhibitor is a member of the potato proteinase inhibitor I family.

Amino Acid Sequence↗

PubMed1984

Characterization of a neutral endopeptidase localized in the mitochondrial matrix of rat anterior pituitary tissue with GnRH as a substrate.

We have determined the subcellular localization of an endopeptidase activity able to degrade gonadotropin releasing hormone (GnRH) and present in the rat adenohypophysis. After fractionation of tissue homogenates in 0.25 M sucrose by differential centrifugation, about 25% of the total cellular GnRH degrading activity was found to be sedimentable and recovered from heavy (M) and light (L) mitochondrial fractions with a distribution pattern similar to that of the mitochondrial and lysosomal reference enzymes cytochrome oxidase and beta-galactosidase. Upon further fractionation on sucrose density gradients, the activity comigrated with mitochondria. The peptidase appears endowed with a structure-linked latency; the activity is low in a freshly prepared mitochondrial fraction and increases upon treatment with membrane disrupting agents in a manner similar to that of malate dehydrogenase, a component of the mitochondrial matrix. Determination of GnRH cleavage sites was performed by amino acid analysis of the fragments obtained after incubation of the peptidase with (3H)-GnRH labelled on the pyroglutamic acid residue, in presence of carboxypeptidase and peptidyldipeptidase inhibitors. The fragments were separated by ion-exchange chromatography on an Aminex Q-15S column and purified by chromatography on silica gel plates. Fragments 1-2, 1-3, 1-4, 1-5 and 1-6 were all present as early as 1 min after the beginning of incubation. Formation of each of them was inhibited to the same extent by EDTA, mersalyl acid, dithioerythritol and Na deoxycholate. The same fragmentation pattern was observed after partial purification of the enzyme by gel filtration. These data indicate that cleavage of several peptide bonds may result from a possibly single endopeptidase located in the mitochondrial matrix space.

Animals↗

PubMed2005

Urinary and plasma organic acids and amino acids in chronic fatigue syndrome.

Previous work by others have suggested the occurrence of one or more chemical or metabolic 'markers' for ME/CFS including specific amino acids and organic acids and a number of unidentified compounds (CFSUM1, CFSUM2). We have shown elsewhere that CFSUM1 is partially derivatised pyroglutamic acid and CFSUM2 partially derivatised serine and have suggested and demonstrated that the analytical methods used were unsuitable to identify or to accurately quantify urinary metabolites. We have now made a detailed analysis of plasma and urinary amino acids and of urinary organic acids from patients with ME/CFS and from three control groups. Fasting blood plasma and timed urine samples were obtained from 31 patients with CFS, 31 age and sex-matched healthy controls, 15 patients with depression and 22 patients with rheumatoid arthritis. Plasma and urinary amino acids and urinary organic acids were determined using established and validated methods and data compared by statistical analysis. None of the previously reported abnormalities in urinary amino acids or of organic acids could be confirmed. Results however provide some evidence in patients with ME/CFS for underlying inflammatory disease and for reduced intramuscular collagen with a lowered threshold for muscle micro-injury. These factors in combination may provide a basis for the fatigue and muscle pain that are the major symptoms in these patients.

Acids↗

PubMed1976

Synthesis and chemical behaviour of D-glucosyl esters of glutamic acid having the side-chain carboxyl group involved in the glycosidic linkage.

Simultaneous and stepwise deprotection of the fully benzylated D-glucosyl esters of 1-benzyl N-benzyloxycarbonyl- and N-tert-butyloxycarbonyl-L-glutamic acid (1 and 5, respectively) have been examined. Catalytic hydrogenation of 1 led to intramolecular aminolysis to give pyroglutamic acid and D-glucose, but similar treatment in the presence of trifluoroacetic acid afforded both anomers of 1-O-(L-gamma-glutamyl)-D-glucopyranose, which were characterized as trifluoroacetates (2alpha and 2beta) and converted into 2,3,4,6-tetra-O-acetyl-1-O-[1-methyl N-(acetyl)-L-glutam-5-oyl]-D-glucopyranose (4) which was also prepared by a definitive method. Hydrogenolysis of 5 gave both anomers of 1-O-[N-(tert-butyloxycarbonyl)-L-gamma-glutamyl]-D-glucopyranose (6), which, upon treatment with trifluoroacetic acid at - 10 degrees, afforded 2alpha and 2beta, respectively. The structure of 6beta was established by its conversion into 2,3,4,6-tetra-O-acetyl-1-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-beta-D-glucopyranose (7beta), whereas similar treatment of 6alpha gave a mixture of 1,3,4,6-tetra-O-acetyl-2-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-alpha-D-glucopyranose (9) and 7alpha. A 1 leads to 2 acyl migration occurred during esterification of the aglycon carboxyl group of 6alpha with diazomethane to give 2-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-alpha-D-glucopyranose (8).

Chemical Phenomena↗

PubMedDate not supplied

Alkaline protease catalysis of a secondary amine to form a peptide bond.

Procedures for peptide bond formation using esters of L-amino acids as the acyl donor and secondary amines such as derivatives of D- or L-proline, or pyroglutamic acid as the nucleophile in anhydrous 2-methyl-2-propanol catalyzed by alcalase or subtilisin Carlsberg have been developed. Kinetic studies have shown that all secondary amines tested had catalytic efficiencies (kcat/km) in the range 84-423 min-1 M-1. Both enzymes have identical catalytic properties. The selectivity of the enzyme-catalyzed reaction in 2-methyl-2-propanol shows that at the s-1 subsite of the enzyme only L-amino acids are substrates as acyl donors, and at the s-1' subsite both D- and L-amino acids are substrates. Optimal conditions for preparing precursors of the renin inhibitors Z-Ala-Pro-OBzl, Z-Lys(Z)-Pro-OBzl and Z-Lys(TFA)-Pro-OBzl were studied.

Amides↗

PubMed2002

Stereoselective synthesis of dipeptide beta-turn mimetics: 7-benzyl and 8-phenyl substituted azabicyclo[4.3.0]nonane amino acid esters.

A stereoselective method has been developed for the synthesis of 7- and 8-substituted dipeptide beta-turn mimetic azabicyclo[4.3.0]nonane amino acid esters. The allyl groups were introduced in high diastereoselectivity, controlled by 3-phenyl or 4-benzyl groups in pyroglutamic acid derivatives 3 or 9, respectively. The precursors, dehydroamino acids 7 and 13 derived from 5 or 11, underwent asymmetric hydrogenations with Burk's DuPHOS Rh(I)-based catalysts to furnish alpha-amino acid derivatives in high stereoselectivity. The resulting amino acids 8 and 14 were converted to the beta-turn mimetics 6,5-bicyclic lactams 1a-d in high yields.

Amino Acids↗

PubMed2004

Discrepin, a new peptide of the sub-family alpha-ktx15, isolated from the scorpion Tityus discrepans irreversibly blocks K+ -channels (IA currents) of cerebellum granular cells.

A new peptide was purified from the venom of the Venezuelan scorpion Tityus discrepans, by high-performance liquid chromatography and its amino acid sequence was completed by Edman degradation and mass spectrometry analysis. It contains 38 amino acid residues with a molecular weight of 4177.7 atomic mass units, tightly folded by three disulfide bridges, and has a pyroglutamic acid at the N-terminal region. This peptide, named Discrepin, was shown to block preferentially the IA currents of the voltage-dependent K+ -channel of rat cerebellum granular cells in culture. The K+ -currents are inhibited in an apparently irreversible manner, whose 50% inhibitory effect is reached with a 190 nM toxin concentration. The systematic nomenclature proposed for this toxin is alpha-KTx15.6.

Amino Acid Sequence↗

PubMed1988

Nucleotide sequence of cloned cDNA coding for pumpkin 11-S globulin beta subunit.

cDNA coding for preproglobulin beta, a precursor protein of 11-S globulin beta subunit, was cloned and the nucleotide sequence has been determined. The sequence covers the whole coding region (1440 base pairs) with 5' and 3' noncoding region (30 and 214 base pairs, respectively). The deduced amino acid sequence of preproglobulin beta consists of a 21-amino-acid N-terminal signal peptide, preceding the acidic gamma polypeptide region (275 amino acids) and the subsequent basic delta region (184 amino acids). The site for post-translational cleavage of the precursor polypeptide to make the gamma and delta chains is estimated to be located between the asparagine-glycine residues. The N-terminal amino acid of the gamma chain of mature 11-S globulin beta subunit was reported to be blocked by 5-oxoproline (pyroglutamic acid) [Ohmiya et al. (1980) Plant Cell Physiol. 21, 157-167]. It was shown that the blocked N-terminal amino acid is coded as a glutamine residue. The derived amino acid sequence was also compared with those of precursor proteins of other 11-S globulins such as soybean glycinin, cotton beta globulin, pea legumin and rape 11-S globulin by dot matrix analysis.

Amino Acid Sequence↗

PubMed1982

Primary structure of horse erythrocyte glycophorin HA. Its amino acid sequence has a unique homology with those of human and porcine erythrocyte glycophorins.

The complete amino acid sequence of the major sialoglycoproteins of horse erythrocyte membranes, glycophorin HA, was determined by manual sequencing methods, using tryptic, chymotryptic, and cyanogen bromide fragments. Glycophorin HA is a polypeptide chain of 120 amino acid residues and contains 10 oligosaccharide units attached to the amino-terminal side of the molecule. Its amino terminus is pyroglutamic acid. All of the oligosaccharides are linked O-glycosidically to threonine or serine residues. The amino acid sequence is consistent with the transmembrane orientation of glycophorins. There is no significant homology between the glycosylated domains of horse, human, and porcine glycophorins, but there is a considerable homology between the hydrophobic domains of the three glycophorins, which interact with the lipid bilayer of the erythrocyte membrane.

Amino Acid Sequence↗

PubMed1984

Special problems encountered during the cyanogen bromide cleavage of lobster arginine kinase.

During structural analysis of Lobster muscle arginine-kinase, we have isolated a CNBr resulting peptide with a blocked N-terminal residue. This peptide was sequenced after unblocking by mild acid treatment (1 N HCl at 100 degrees C for 10 min). The blocked form is not due to the formation of pyroglutamic acid nor is it due to the formation of diketopiperazine. We have applied the experimental conditions used for CNBr cleavage of lobster arginine-kinase to a synthetic peptide the structure of which is similar to the above CNBr peptide. We bring evidence that during CNBr cleavage partial formylation occurs with a possible cyclization of a 7 membered ring of Gly--Asp...

Amino Acid Sequence↗

PubMed1999

Production of organic acids and amino acids from fish meat by sub-critical water hydrolysis

Fish meat was easily liquefied by hydrolysis under subcritical conditions without oxidants, and aqueous phase and water-insoluble phase containing oil and fat-like solid were formed. Lactic acid found in the raw fish meat (about 0.03 g/g-dry meat) was stable up to the reaction temperature 513 K (3.35 MPa). Pyroglutamic acid was produced with a yield of 0.095 kg/kg of dry meat by 30 min reaction at 553 K (6.42 MPa). Amino acids such as cystine, alanine, glycine, and leucine were produced in the temperature range 513-623 K with a maximum peak at 543 K. Amounts of cystine, alanine, glycine, and leucine produced in 5 min at 543 K (5.51 MPa) were 0.024, 0.013, 0. 009, and 0.004 kg/kg of dry meat, respectively. The oil extracted with hexane contained useful fatty acids such as eicosapentanoic acid (EPA) and docosahexianoic acid (DHA). Thus, subcritical water hydrolysis would be an efficient process for recovering useful substances from organic waste such as fish waste discarded from fish market.

Journal Article↗

PubMed2000

Rational design of highly diastereoselective, organic base-catalyzed, room-temperature Michael addition reactions.

Via the rational design of a single-preferred transition state, stabilized by electron donor-acceptor-type attractive interactions, structural and geometric requirements for the corresponding starting compounds have been determined. The Ni(II) complex of the Schiff base of glycine with o-[N-alpha-picolylamino]acetophenone, as a nucleophilic glycine equivalent, and N-(trans-enoyl)oxazolidin-2-ones, as derivatives of an alpha,beta-unsaturated carboxylic acid, were found to be the substrates of choice featuring geometric/conformational homogeneity and high reactivity. The corresponding Michael addition reactions were found to proceed at room temperature in the presence of catalytic amounts of DBU to afford quantitatively the addition products with virtually complete diastereoselectivity. Acidic decomposition of the products followed by treatment of the reaction mixture with NH4OH gave rise to the diastereomerically pure 3-substituted pyroglutamic acids.

Catalysis↗

PubMed1973

Inhibition of 5-oxoprolinase by 2-imidazolidone-4-carboxylic acid.

L-2-Imidazolidone-4-carboxylic acid is an effective competitive inhibitor of the reaction catalyzed by 5-oxoprolinase, in which 5-oxo-L-proline (L-pyroglutamic acid, L-2-pyrrolidone-5-carboxylic acid, L-5-oxopyrrolidine-2-carboxylic acid) is converted to L-glutamate, with concomitant cleavage of ATP to ADP and orthophosphate. L-2-Imidazolidone-4-carboxylate decreased the rate of metabolism of 5-oxo-L-[(14)C]proline to (14)CO(2) by rat-kidney slices but had no effect on the metabolism of [(14)C]glutamate. Mice injected with L-2-imidazolidone-4-carboxylate exhibited greatly reduced ability to metabolize 5-oxo-L-proline, but metabolized glutamate at an essentially normal rate. The findings provide an approach to an animal model for the human condition 5-oxoprolinuria, in which there is apparently a deficiency of renal 5-oxoprolinase activity. The evidence indicates that 5-oxoproline is a normal metabolite.

Amidohydrolases↗

PubMed1981

Composition and sequence studies show that A/duck/Ukraine/1/63 haemagglutinin (Hav7) belongs to the Hong Kong (H3) subtype.

The haemagglutinin chains HA1 and HA2 from the avian influenza virus A/duck/Ukraine/1/63 (Hav7, Neq2) have been subjected to amino acid analysis and N-terminal sequencing. Automated sequenator analysis of HA1 (40 cycles), after enzymic removal of the N-terminal pyroglutamic acid blocking group, and HA2 (43 cycles) showed that the Hav7 haemagglutinin closely resembled the human Hong Kong (H3) haemagglutinins including the presence of the characteristic extended 10 residue sequence at the N-terminus of HA1. These findings, together with the amino acid compositions for both chains, demonstrate that the Hav7 haemagglutinin is structurally similar to the Hong Kong (H3) haemagglutinins.

Amino Acid Sequence↗

PubMed2003

Characterization of a new bradykinin-potentiating peptide (TmF) from Trimeresurus mucrosquamatus.

A novel bradykinin-potentiating peptide (BPP), designated as TmF, has been purified to homogeneity from the venom of Trimeresurus mucrosquamatus by 70% cold methanol extraction, Sephadex G-15 gel filtration and reverse-phase high performance liquid chromatography (RP-HPLC). The amino acid sequence of TmF was determined to be pGlu-Gly-Arg-Pro-Leu-Gly-Pro-Pro-Ile-Pro-Pro (pGlu denotes pyroglutamic acid), which shared high homology with other BPPs. The molecular mass of TmF was 1.1107 kD as determinated by electrospray ionization-mass spectrometry (ESI-MS), which was in accordance with the calculated value of 1.1106 kD. The potentiating unit of TmF to bradykinin-induced (BK-induced) contraction on the guinea-pig ileum in vitro was (1.13 +/-0.3) unit (mg/L), and TmF (5.0 x10(-4) mg/kg) increased the pressure-lowering-effect of bradykinin (5.0 x10(-5 )mg/kg) with approximate descent value of (14 +/-2) mmHg. In addition, TmF inhibited the conversion of angiotensin I to angiotensin II, 2 x10(-3) mg of TmF caused 50% inhibition (IC(50)) of angiotensin- converting enzyme (ACE) hydrolyzing activity to bradykinin.

Amino Acid Sequence↗