KOSEN 한인과학기술자네트워크

peptide degradation과 관련하여 상용 DB인 DIALOG를 통해 검색된 관련 자료들의 서지사항입니다. 참고해 보시기 바랍니다. * 5/9/1 (Item 1 from file: 5) 10416459 Biosis No.: 199699037604 Peptide degradation: Effect of substrate phosphorylation on aminopeptidasic hydrolysis. Author: Murray Pedro Fernandez; Hammerschmidt Pablo; Samela Andrea; Passeron Susana (a) Author Address: (a)Catedra Microbiol., Fac. Agronomia, Universidad Buenos Aires, Avda San Martin 4453, 1417 Buenos **Argentina Journal: International Journal of Biochemistry & Cell Biology 28 ( 4 ): p 451-456 1996 ISSN: 1357-2725 Document Type: Article Record Type: Abstract Language: English Abstract: The effect of substrate phosphorylation on the susceptibility to exopeptidasic attack by leucyl aminopeptidase of swine kidney, alanyl aminopeptidase from human liver and aminopeptidase N of Escherichia coli was investigated using a synthetic heptapeptide (L-R-R-A-S-L-G) and its phosphorylated derivative. The enzyme-catalyzed products were analyzed by thin layer chromatography and electrophoresis. The sensitivities of peptide and phosphopeptide to leucyl aminopeptidase digestion were then compared. Data obtained indicated that when phosphopeptide was used as substrate one main product accumulated, which corresponded to the fragment A-S(P)-L-G, while unphosphorylated peptide was completely degraded to its constituent amino acids. Identical results were obtained using aminopeptidase N of E. coli. Using alanyl aminopeptidase as enzyme, the results obtained were essentially similar, since the exopeptidasic activity on the phosphorylated peptide was strongly hampered in the vicinity of phosphoseryl residue leading to accumulation of the same phosphorylated product, although this enzyme could not completely degrade the unphosphorylated peptide. It was concluded that phosphorylation of substrates does effect enzymic degradation of proteins. * 5/9/2 (Item 1 from file: 73) 05764236 EMBASE No: 1994166038 Chemical pathways of peptide degradation. VI. Effect of the primary sequence on the pathways of degradation of aspartyl residues in model hexapeptides Oliyai C.; Borchardt R.T. Dept. of Pharmaceutical Chemistry, 3006 Malott Hall, University of Kansas,Lawrence, KS 66045 United States Pharmaceutical Research ( PHARM. RES. ) ( United States ) 1994 , 11/5 (751-758) CODEN: PHREE ISSN: 0724-8741 Document Type: Journal ; Article Language: ENGLISH Summary Language: ENGLISH The influence of the primary sequence on the degradation of Aspsup 4 residues (e.g., formation of the cyclic imide and Asp-X and/or X-Asp amide bond hydrolysis) was investigated using Val-Tyr-Y-Asp-X-Ala hexapeptides. These reactions were proposed to involve cyclization, which would duly be sensitive to steric hindrance. The effects on the rates of individual degradation routes and product distribution under both acidic and alkaline conditions were assessed upon substitutions made on the C-terminal side (X) and on the N-terminal side (Y) of the Asp residue. As expected, the rate of intramolecular formation of cyclic imide and, thus, the product yield were most affected by the size of the amino acid on the C-terminal side of the Asp residue. However, such structural changes had little or no impact on the rate of Asp-X and Y-Asp amide bond hydrolysis. In the former case, the substituted site was one atom removed from the reaction site, accounting for the diminished steric effect observed. As for the latter, the site of substitution was not a participant in the reaction itself, and hence, the rate was unperturbed by this modification. Placing Ser and Val C terminally to the Asp residue prompted racemization and peptide bond hydrolysis to occur under alkaline conditions. N-Terminal substitution of Pro with Gly had no effect on the rate of isomerization via cyclic imide formation but greatly enhanced the rate of Y-Asp amide bond hydrolysis. * 5/9/3 (Item 2 from file: 73) 05557573 EMBASE No: 1993325673 Chemical pathways of peptide degradation. V. Ascorbic acid promotes rather than inhibits the oxidation of methionine to methionine sulfoxide in small model peptides Li S.; Schoneich C.; Wilson G.S.; Borchardt R.T. Dept. of Pharmaceutical Chemistry, University of Kansas,Lawrence, KS 66045 United States Pharmaceutical Research ( PHARM. RES. ) ( United States ) 1993 , 10/11 (1572-1579) CODEN: PHREE ISSN: 0724-8741 Document Type: Journal ; Article Language: ENGLISH Summary Language: ENGLISH The effect of primary structure and external conditions on the oxidation of methionine to methionine sulfoxide by the ascorbate/Fesup 3sup + system was studied in small model peptides. Degradation kinetics and yield of sulfoxide formation were dependent on the concentration of ascorbate and Hsup +, with a maximum rate observed at pH 6-7. Phosphate buffer significantly accelerated the peptide degradation compared to Tris, HEPES, and MOPS buffers; however, the formation of sulfoxide was low. The oxidation could not be inhibited by the addition of EDTA. Other side products besides sulfoxide were observed, indicating the existence of various other pathways. The influence of methionine location at the C terminus, at the N terminus, and in the middle of the sequence was investigated. The presence of histidine in the sequence markedly increased the degradation rate as well as the sulfoxide production. The histidine catalysis of methionine oxidation occurred intramolecularly with a maximum enhancement of the oxidation rate and sulfoxide production when one residue was placed between the histidine and the methionine residue. * 5/9/4 (Item 3 from file: 73) 05252759 EMBASE No: 1993020844 Chemical pathways of peptide degradation. IV. Pathways, kinetics, and mechanism of degradation of an aspartyl residue in a model hexapeptide Oliyai C.; Borchardt R.T. Dept. of Pharmaceutical Chemistry, University of Kansas,Lawrence, KS 66045 United States Pharmaceutical Research ( PHARM. RES. ) ( United States ) 1993 , 10/1 (95-102) CODEN: PHREE ISSN: 0724-8741 Document Type: Journal ; Article Language: ENGLISH Summary Language: ENGLISH In this study the hexapeptide Val-Tyr-Pro-Asp-Gly-Ala (Asp-hexapeptide) was used as a model to investigate the kinetics of aspartate degradation in aqueous solution. The apparent rate of degradation of the Asp-hexapeptide was determined as a function of pH, buffer concentration, and temperature. At very acidic pH levels (0.3, 1.1, 1.5, 2.0, and 3.0), the apparent rate of degradation followed pseudo-first-order kinetics. In this pH region, the Asp-hexapeptide predominantly underwent specific acid-catalyzed hydrolysis of the Asp-Gly amide bond (Asp-X hydrolysis) to form a tetrapeptide (Val-Tyr-Pro-Asp) and a dipeptide (Gly-Ala). In addition, parallel formation of a cyclic imide intermediate could be observed, although no isoAsp-hexapeptide was detected. At pH 4.0 and 5.0, the Asp-hexapeptide simultaneously isomerized via the cyclic imide to form the iso-Asp-hexapeptide and underwent Asp-X hydrolysis to produce the cleavage products. The pH-rate profiles (pH 0.3-5.0) for the Asp-X hydrolysis and the formation of cyclic imide revealed that the degree of ionization of the carboxylic acid side chain of Asp residue significantly altered the rate of reaction, with the ionized form being more reactive than the unionized form. Little or no buffer catalysis was observed for either pathway. Solvent isotope experiments were used to probe the mechanism of the Asp-X hydrolysis reaction. At pH values above 6.0, the apparent rate of degradation of the Asp-hexapeptide followed pseudo-first-order reversible kinetics, with the isoAsp-hexapeptide being the only observed product (isomerization). Above pH 8.0, the isomerization kinetics were found to be independent of pH and buffer concentration. The kinetics of degradation of Asp-hexapeptide (Val-Tyr-Pro-Asp-Gly-Ala) and Asn-hexapeptide (Val-Tyr-Pro-Asn-Gly-Ala) were compared to determine the relative instability of the Asp and Asn residues and to understand the mechanism of formation of cyclic imide at near neutral to basic pH. * 5/9/5 (Item 4 from file: 73) 04450331 EMBASE No: 1990338440 Chemical pathways of peptide degradation. III. effect of primary sequence on the pathways of deamidation of asparaginyl residues in hexapeptides Patel K.; Borchardt R.T. Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66045 United States Pharmaceutical Research ( PHARM. RES. ) ( United States ) 1990 , 7/8 (787-793) CODEN: PHREE ISSN: 0724-8741 Document Type: Journal ; Article Language: ENGLISH Summary Language: ENGLISH Deamidation of Asn residues can occur either by direct hydrolysis of the Asn residue or via a cyclic imide intermediate. The effects of primary sequence on the pathways of deamidation of Asn residues were studied using Val-Tyr-X-Asn-Y-Ala hexapeptides with substitution on the C-terminal side (Y) and on the N-terminal side (X) of the Asn residue. In acidic media the peptides deamidate by direct hydrolysis of the Asn residue to yield only Asp peptides, whereas under neutral or alkaline conditions, the peptides deamidate by formation of the cyclic imide intermediates which hydrolyze to yield both isoAsp and Asp peptides. At neutral to alkaline pH's the rate of deamidation was significantly affected by the size of the amino acid on the C-terminal side of the Asn residue. The amino acid on the C-terminal side of the Asn residue has no effect on the rate of deamidation at acidic pH. Changes in the structure of the amino acid on the N-terminal side of the Asn residue had no significant effect on the rate of deamidation at all the pH's studied. For peptides that underwent deamidation slowly, a reaction involving the attack of the Asn side chain on the peptide carbonyl carbon resulting in peptide bond cleavage was also observed. * 5/9/15 (Item 10 from file: 155) 06443364 90370722 Chemical pathways of peptide degradation. II. Kinetics of deamidation of an asparaginyl residue in a model hexapeptide. Patel K; Borchardt RT Department of Pharmaceutical Chemistry, University of Kansas, Lawrence 66045. Pharmaceutical research ( UNITED STATES ) Jul 1990 , 7 (7) p703-11 , ISSN 0724-8741 Journal Code: PHS Languages: ENGLISH Document type: JOURNAL ARTICLE Journal Announcement: 9012 Subfile: INDEX MEDICUS Deamidation of Asn residues is a major chemical pathway of degradation of peptides and proteins. To understand better the external factors that influence deamidation, we studied the degradation of the hexapeptide Val-Tyr-Pro-Asn-Gly-Ala, a fragment of adrenocorticotropic hormone, by HPLC. The deamidation of this model peptide showed marked dependence on pH, temperature, and buffer composition. In the pH range 5 to 12, the peptide deamidated exclusively via a cyclic imide intermediate with the formation of both the Asp- and the isoAsp-hexapeptides. Buffer catalysis was also observed in the pH range of 7 to 11. However, at acidic pH's, the pathway of deamidation involved direct hydrolysis of the amide side chain of Asn residue to produce only the Asp-hexapeptide. >peptide를 degradation시켜 amino acid를 얻고자 합니다. >peptide를 분해시켜 amino acid를 얻을 수 있는 화학적, 물리적 >방법이 무엇인지 궁금하며, 그에 관련된 기계장비 등을 알고 싶습니다.

>peptide를 degradation시켜 amino acid를 얻고자 합니다. >peptide를 분해시켜 amino acid를 얻을 수 있는 화학적, 물리적 >방법이 무엇인지 궁금하며, 그에 관련된 기계장비 등을 알고 싶습니다. peptide degradation에 관한 보고서중 귀하께 도움이 될만한 자료 두가지를 올려드립니다.