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At least 19 recordsLinked to original sources
PubMed1976

Partial amino-acid sequence of the precursor of an immunoglobulin light chain containing NH2-terminal pyroglutamic acid.

Analyses of amino-acid sequences of the total cell-free products programmed by the mRNA of MOPC-104E gamma light (L)-chain show that over 95% of the products have sequences of a distinct protein that correspond to the L-chain precursor. In this precursor an extra piece is coupled to the NH2-terminus of the mature L-chain. Analyses of products labeled with [3H]alanine, [3H]leucine, and [3H]proline demonstrate that the extra piece is composed of at least 18 residues. Analyses of [35S]methione-labeled product indicate that the extra piece may contain an additional NH2-terminal methionine, which is detected in about 10% of the molecules. Partial recovery of the NJ2-terminal methionine (alanine, leucine, and proline are recovered in yields close to theoretical, greater than 95%) suggests that it is the initiator methionine, which is known to be short lived in eukaryotes due to rapid hydrolysis. Thus, the extra piece seems to be 19 residues in length, and it contains one methionine at the NH2-terminus, three alanines at positions 2, 12, and 17, and five leucines at positions 6, 8, 10, 11, and 13. The close gathering of leucine residues, as well as their abundance (26%), suggest that the extra piece would be quite hydrophobic. Hydrophobicity seems to be a general property of the extra piece, since similar clusters of leucine were found in the precursors of 3 KL-chains (Burstein, Y. & Schechter, I. (1976) Biochem. J. 157, 145-151). The NH2-terminus of the mature MOPC-104E gamma L-chain is blocked by pyroglutamic acid. The fact that in the precursor a peptide segment precedes this NH2-terminus establishes that pyroglutamic acid is not the initiator residue for synthesis of the L-chain. Apparently, the pyroglutamic acid is formed by cyclization of glutamic acid or glutamine during cleavage of the extra piece to yield the mature L-chain.

Amino Acid Sequence↗
PubMed1975

Initiation by methionine of mouse immunoglobulin light chain containing NH-2terminal pyroglutamic acid.

The mechanism of biosynthesis of NH2-terminal pyroglutamic acid has been studied in a mouse plasmacytoma (RPC-20) which produces an immunoglobulin light (lambda) chain containing NH2-terminal pyroglutamic acid. To this end, initation of lambda chain synthesis in plasmacytoma cell suspensions has been investigated. The analysis of radioactive lambda chain synthesis by these cells was accomplished with an antibody preparation specific for the precipitation of lambda chain protein from total plasmacytoma protein. NH2-terminal analysis of plasmacytoma cells labeled with [35S]methionine showed that the ratio of radioactivity in NH2-terminal methionine to total incorporation in lambda chain was greater at 2 min of labeling than at 60 min. However, such a pattern of transient labeling of the NH2 terminus of the lambda chain was not obtained when cells were incubated with tritiated leucine, arginine, or tryptophan. The data indicate that methionine is the initiator amino acid for the synthesis of lambda chain containing NH2-terminal pyroglutamic acid.

Amino Acid Sequence↗
PubMed1975

Increased pyroglutamic acid levels in patients on artificial diets.

Increased plasma and urine levels of pyroglutamic acid were found in 4 patients being fed the low-lactose food Nutramigen. Pyroglutamic acid was detected and estimated by a variety of methods, and the merits of the techniques used and their application in a screening programme are discussed.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1979

Synthesis of a series of residue 1 (pyroglutamic acid) analogs of thyrotrophin releasing hormone.

This report describes the synthesis of 23 analogs of thyrotrophin releasing hormone, L-pyroglutamic acid-L-histidyl-L-prolineamide, where only the pyroglutamic acid moiety is modified. Twelve of the analogs contain different heterocyclic rings or are derivatized pyrrolidone rings. The syntheses of these pyroglutamic acid analogs are also described. Peptide bond formation was generally achieved by catalyzing carbodiimide coupling with 1-hydroxybenzotriazole. The histidine side chain was protected with the 2,4-dinitrophenyl group during di- and tripeptide synthesis and was removed with benzenethiol Final purification of tripeptides involved passage of synthetic material over a Dowex 1--X4 (bicarbonate) column. The route for synthesis of thyrotrophin releasing hormone and its analogs is highly efficient, since the native hormone may be obtained with 90% efficiency.

Amino Acids↗
PubMed1979

N-alpha-Cocoyl-L-arginine ethyl ester, DL-pyroglutamic acid salt, as an inactivator of hepatitis B surface antigen.

N-alpha-Cocoyl-L-arginine ethyl ester, DL-pyroglutamic acid salt (CAE), exhibited a strong inactivating effect on hepatitis B surface antigen. Concentrations of CAE required for 50 and 100% inactivation of the antigen were 0.01 to 0.025% and 0.025 to 0.05% respectively. CAE completely inactivated hepatitis B surface antigen at the lowest concentration compared with various compounds including about 500 amino acid derivatives, sodium hypochlorite, 2,4,4'-trichloro-2'-hydroxydiphenyl ether, and some detergents. Furthermore, CAE inactivated vaccinia virus, herpes simplex virus, and influenza virus, whereas poliovirus was not inactivated at all. The results suggest that the inactivating effects of CAE are related to interaction with lipid-containing viral envelopes.

Antiviral Agents↗
PubMed1977

Glutamine as a precursor to N-terminal pyrrolid-2-one-5-carboxylic acid in mouse immunoglobulin lambda-type light chains. Amino acid-sequence variability at the N-terminal extra piece of lambda-type light-chain precursors.

The mRNA molecules coding for three mouse immunoglobulin lambda-type light (L) chains (MOPC-104E lambda(1), RPC-20 lambda(1), MOPC-315 lambda(2)) programme the cell-free synthesis of precursors larger than the mature proteins. Radioactive amino acid-sequence analyses of each of the three precursors labelled with [(3)H]alanine, [(3)H]serine, [(3)H]glutamine, [(3)H]glutamic acid and [(3)H]threonine showed that an extra piece, at least 18 residues long, is linked to the N-terminus of the mature L-chains. The N-terminal extra-peptide segment may be 19 residues long, since analyses of precursors labelled with [(35)S]methionine indicated an additional N-terminal methionine residue which was recovered in low yields. Presumably this is the initiator methionine, which is known to be short lived in eukaryotes. The mature forms of MOPC-104E, RPC-20 and MOPC-315 lambda L-chains are blocked at the N-termini by pyrrolid-2-one-5-carboxylic acid (pyroglutamic acid). Sequence analyses of precursors labelled with [(3)H]glutamine and [(3)H]glutamic acid showed incorporation only of glutamine in a position that matches with the position of pyrrolid-2-one-5-carboxylic acid in the mature forms of all three precursors, and incorporation of glutamic acid in other positions. The data showed the absence of glutamine-glutamic acid interconversion, since the radioactive peaks obtained from either (3)H-labelled amino acid were discrete, and free from cross-contamination. These results prove that glutamine is the precursor amino acid of pyrrolid-2-one-5-carboxylic acid at the N-termini of the mature MOPC-104E lambda(1), RPC-20 lambda(1) and MOPC-315 lambda(2) L-chains. Thus the formation of pyrrolid-2-one-5-carboxylic acid by cyclization of glutamine is a post-translational event which occurs after, or concomitant with, cleavage of the extra piece from the precursor to yield the mature L-chain. The variable (V) regions (110 amino acid residues) of mouse lambda L-chains are quite similar: when compared with that of MOPC-104E lambda(1) chain, the V-region of RPC-20 lambda(1) chain differs in one residue, and the V-region of MOPC-315 lambda(2) chain differs in 11 residues. The partial sequence data show that the N-terminal extra pieces of the two lambda(1) L-chain precursors have, so far, identical partial sequences; the extra piece of the lambda(2) L-chain precursor differs from these in at least three out of 19 positions.

Amino Acid Sequence↗
PubMed1977

Isolation and characterization of highly purified alpha-1-antitrypsin.

Highly purified human alpha-1-antitrypsin (phenotype MM) was obtained by an original method of preparative electrophoresis. The criteria of homogeneity were assured by one arc in crossed immunoelectrophoresis and one band on polyacrylamide gel. A unique N-terminal amino acid (pyroglutamic acid) and a unique C-terminal residue (lysine) were identified. Determined by gel electrophoresis, its molecular weight was 47,000 daltons.

Amino Acid Sequence↗
PubMed1976

Specificity and inhibition of gamma-glutamyl transpeptidase in guinea pig intestines.

Gamma-Glutamyl transpeptidase activity in guinea pig intestine was tested toward 8 monoglutamyl and 4 diglutamyl substrates. Distinct differences in specificity and activity related to ontogenetic development were noted. A mixture of L-serine and borate inhibited specifically gamma-glutamyl transpeptidase activity of homogenates and accumulation of naphthylamine and 14C-substances in slices of intestine incubated with gamma-L-14C-glutamyl-alpha-naphthylamide. The same mixture, administered per os together with 14C-gamma-glutamyl substrate, specifically inhibited urinary excretion of 14C-substance, but had no effect on the rate of excretion of glycine, L-glutamic acid or L-pyroglutamic acid.

Age Factors↗
PubMed2026

A yeast model of 5-oxoproline accumulation reveals a general toleration to 5-oxoproline.

5-oxoproline (5-OP) or pyroglutamic acid is an intermediate in the degradation arc of the glutathione cycle. It is metabolized into glutamate through the action of the 5-oxoprolinase enzyme, the only enzyme known to act on this metabolite. 5-OP has long been known to be relatively inert with a proposed role as an osomoprotectant. Recent studies on the 5-oxoprolinase enzyme in mammalian cells have, however, shown that knockdown or deletion of 5-oxoprolinase makes mice (and humans) prone to heart failure, an effect ascribed to oxidative stress caused by a twofold increase in 5-OP. To examine the consequences of 5-oxoproline accumulation more rigorously, we created a yeast model for 5-oxoproline accumulation. Using this model, we observed retardation of growth only when intracellular levels of 5-OP were increased 12- to 20-fold over normal levels. Performing an analysis of transcriptomic changes under these conditions, we observed a large number of genes were differentially regulated and while there was no unifying dysregulated pathway, there was an upregulation of various efflux pumps. Ultimately, modulating the expression of these genes by knockout or overexpression highlighted that many of the upregulated genes were involved in the cellular response to 5-OP accumulation. However, our results failed to show any significant oxidative stress response. In conclusion, our study suggests a need to reevaluate previous suppositions of the 5-OP induced oxidative stress response and proposes alternate mechanisms for this effect.

Pyrrolidonecarboxylic Acid↗
PubMedDate not supplied

Labilization of the phosphoester linkage in enzyme-inhibitor complexes of aspartate aminotransferase.

Individual enzyme-inhibitor complexes with characteristic absorption spectra have been obtained as a result of the reaction of the apoenzyme of aspartate aminotransferase with Nalpha-(5'-phosphopyridoxyl)-L-glutamic acid, Nalpha-(5'-phosphopyridoxyl)-D-glutamic acid, and Nalpha-(5'-phosphopyridoxyl)-L-pyroglutamic acid. The stability of the enzyme-inhibitor complexes has been investigated under various conditions, viz., reactivation by the coenzyme, denaturation by urea, variations in the pH. It has been shown that the complexes formed by the last two inhibitors are reactivated by pyridoxal-5'-phosphate and that the inhibitor can be released under mild conditions. The enzyme-inhibitor complex formed by Nalpha-(5'-phosphopyridoxyl)-L-glutamic acid, on the other hand, was not reactivated by the coenzyme. Pyridoxylglutamic acid has been isolate in attempts to release the inhibitor. The dephosphorylation of the inhibitor has been associated both with the hydrolysis of a phosphate bond involving the enzyme and with the phosphorylation of aspartate aminotransferase. A 32P peptide containing 13 amino acids has been isolated from the tryptic hydrolysate of the enzyme-inhibitor complex (formed by a 32P inhibitor). The data obtained have been interpreted on the basis of an assumption that the phosphate group of the coenzyme has an active role in the enzymatic transamination reaction.

Apoenzymes↗
PubMed1992

Cloning and sequencing of the xynA gene encoding xylanase A of Aspergillus kawachii.

We have cloned the xynA gene coding for xylanase A, a major component of the xylanase family, from Aspergillus kawachii. The cDNA was isolated from an A. kawachii cDNA library by immunoscreening using antibody raised against the purified xylanase A protein. Nucleotide sequence analysis of the cDNA showed a 981-bp open reading frame that encoded a protein of 327 amino acid residues. The signal peptide was composed of 25 amino acid residues and the N-terminus of the mature protein was pyroglutamic acid. The transformed yeast with a cloned cDNA produced xylanase. The genomic DNA was arranged as ten exons and nine introns.

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↗