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1. 成人におけるセリアック病の病因、疫学、および臨床症状 pathogenesis epidemiology and clinical manifestations of celiac disease in adults

English Journal

Oxidation-induced structural changes of ceruloplasmin foster NGR-motifs deamidation that promote integrin binding and signalling.

Barbariga M, Curnis F, Spitaleri A, Andolfo A, Zucchelli C, Lazzaro M, Magnani G, Musco G, Corti A, Alessio M.Author information San Raffaele Scientific Institute, Italy.AbstractAsparagine deamidation occurs spontaneously in proteins during aging; deamidation of Asn-Gly-Arg (NGR) sites can lead to the formation of isoAsp-Gly-Arg (isoDGR), a motif that can recognize the RGD-binding site of integrins. Ceruloplasmin (Cp), a ferroxidase present in the cerebrospinal fluid (CSF), contains two NGR-sites in its sequence: one exposed on the protein surface (568NGR), and the other buried in the tertiary structure (962NGR). Considering that Cp can undergo oxidative modifications in the CSF of neurodegenerative diseases, we investigated the effect of oxidation on the deamidation of both NGR-motifs and, consequently, on the acquisition of integrin-binding properties. We observed that the exposed 568NGR-site can deamidate under conditions mimicking accelerated Asn aging. In contrast the hidden 962NGR-site can deamidate exclusively when aging occurs under oxidative conditions, suggesting that oxidation-induced structural changes foster deamidation at this site. NGR-deamidation in Cp was associated with gain of integrin-binding function, intracellular signalling and cell pro-adhesive activity. Finally, Cp aging in the CSF from Alzheimer disease patients, but not in control CSF, causes Cp deamidation with gain of integrin-binding function, suggesting that this transition might also occur in pathological conditions. In conclusion, both Cp's NGR-sites can deamidate during aging under oxidative conditions, likely as a consequence of oxidative-induced structural changes, thereby promoting a gain-of-function in integrin binding, signalling and cell adhesion.
The Journal of biological chemistry.J Biol Chem.2013 Dec 23. [Epub ahead of print]
Asparagine deamidation occurs spontaneously in proteins during aging; deamidation of Asn-Gly-Arg (NGR) sites can lead to the formation of isoAsp-Gly-Arg (isoDGR), a motif that can recognize the RGD-binding site of integrins. Ceruloplasmin (Cp), a ferroxidase present in the cerebrospinal fluid (CSF),
PMID 24366863

Deamidation of asparagine to aspartate destabilizes Cu, Zn superoxide dismutase, accelerates fibrillization, and mirrors ALS-linked mutations.

Shi Y, Rhodes NR, Abdolvahabi A, Kohn T, Cook NP, Marti AA, Shaw BF.Author information Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76706, United States.AbstractThe reactivity of asparagine residues in Cu, Zn superoxide dismutase (SOD1) to deamidate to aspartate remains uncharacterized; its occurrence in SOD1 has not been investigated, and the biophysical effects of deamidation on SOD1 are unknown. Deamidation is, nonetheless, chemically equivalent to Asn-to-Asp missense mutations in SOD1 that cause amyotrophic lateral sclerosis (ALS). This study utilized computational methods to identify three asparagine residues in wild-type (WT) SOD1 (i.e., N26, N131, and N139) that are predicted to undergo significant deamidation (i.e., to >20%) on time scales comparable to the long lifetime (>1 year) of SOD1 in large motor neurons. Site-directed mutagenesis was used to successively substitute these asparagines with aspartate (to mimic deamidation) according to their predicted deamidation rate, yielding: N26D, N26D/N131D, and N26D/N131D/N139D SOD1. Differential scanning calorimetry demonstrated that the thermostability of N26D/N131D/N139D SOD1 is lower than WT SOD1 by ~2-8 °C (depending upon the state of metalation) and <3 °C lower than the ALS mutant N139D SOD1. The triply deamidated analog also aggregated into amyloid fibrils faster than WT SOD1 by ~2-fold (p < 0.008**) and at a rate identical to ALS mutant N139D SOD1 (p > 0.2). A total of 534 separate amyloid assays were performed to generate statistically significant comparisons of aggregation rates among WT and N/D SOD1 proteins. Capillary electrophoresis and mass spectrometry demonstrated that ~23% of N26 is deamidated to aspartate (iso-aspartate was undetectable) in a preparation of WT human SOD1 (isolated from erythrocytes) that has been used for decades by researchers as an analytical standard. The deamidation of asparagine--an analytically elusive, sub-Dalton modification--represents a plausible and overlooked mechanism by which WT SOD1 is converted to a neurotoxic isoform that has a similar structure, instability, and aggregation propensity as ALS mutant N139D SOD1.
Journal of the American Chemical Society.J Am Chem Soc.2013 Oct 23;135(42):15897-908. doi: 10.1021/ja407801x. Epub 2013 Oct 10.
The reactivity of asparagine residues in Cu, Zn superoxide dismutase (SOD1) to deamidate to aspartate remains uncharacterized; its occurrence in SOD1 has not been investigated, and the biophysical effects of deamidation on SOD1 are unknown. Deamidation is, nonetheless, chemically equivalent to Asn-t
PMID 24066782

Application of protein N-terminal amidase in enzymatic synthesis of dipeptides containing acidic amino acids specifically at the N-terminus.

Arai T, Noguchi A, Takano E, Kino K.Author information Department of Applied Chemistry, Waseda University, Shinjuku-ku, Tokyo, Japan.AbstractDipeptides exhibit unique physiological functions and physical properties, e.g., l-aspartyl-l-phenylalanine-methyl ester (Asp-Phe-OMe, aspartame) as an artificial sweetener, and functional studies of peptides have been carried out in various fields. Therefore, to establish a manufacturing process for the useful dipeptides, we investigated its enzymatic synthesis by utilizing an l-amino acid ligase (Lal), which catalyzes dipeptide synthesis in an ATP-dependent manner. Many Lals were obtained, but the Lals recognizing acidic amino acids as N-terminal substrates have not been identified. To increase the variety of dipeptides that are enzymatically synthesized, we proposed a two-step synthesis: Asn-Xaa and Gln-Xaa (Asn, l-asparagine; Gln, l-glutamine; and Xaa, arbitrary amino acids) synthesized by Lals were continuously deamidated by a novel amidase, yielding Asp-Xaa and Glu-Xaa (Asp, l-aspartic acid; and Glu, l-glutamic acid). We searched for amidases that specifically deamidate the N-terminus of Asn or Gln in dipeptides since none have been previously reported. We focused on the protein N-terminal amidase from Saccharomyces cerevisiae (NTA1), and assayed its activity toward dipeptides. Our findings showed that NTA1 deamidated l-asparaginyl-l-valine (Asn-Val) and l-glutaminyl-glycine (Gln-Gly), but did not deamidate l-valyl-l-asparagine and l-alanyl-l-glutamine, suggesting that this deamidation activity is N-terminus specific. The specific activity toward Asn-Val and Gln-Gly were 190 ± 30 nmol min(-1) mg(-1)·protein and 136 ± 6 nmol min(-1) mg(-1)·protein. Additionally, we examined some characteristics of NTA1. Acidic dipeptide synthesis was examined by a combination of Lals and NTA1, resulting in the synthesis of 12 kinds of Asp-Xaa, including Asp-Phe, a precursor of aspartame, and 11 kinds of Glu-Xaa.
Journal of bioscience and bioengineering.J Biosci Bioeng.2013 Apr;115(4):382-7. doi: 10.1016/j.jbiosc.2012.10.024. Epub 2012 Dec 4.
Dipeptides exhibit unique physiological functions and physical properties, e.g., l-aspartyl-l-phenylalanine-methyl ester (Asp-Phe-OMe, aspartame) as an artificial sweetener, and functional studies of peptides have been carried out in various fields. Therefore, to establish a manufacturing process fo
PMID 23218487

Japanese Journal

Application of protein N-terminal amidase in enzymatic synthesis of dipeptides containing acidic amino acids specifically at the N-terminus(ENZYMOLOGY, PROTEIN ENGINEERING, AND ENZYME TECHNOLOGY)