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MOTOYOSHI NOMIZU YOSHIMASA INAGAKI TAKEYOSHI YAMASHITA AKO OHKUBO AKIRA OTAKA NOBUTAKA FUJII PETER P. ROLLER HARUAKI YAJIMA 《Chemical biology & drug design》1991,37(2):145-152
A new two-step deprotection/cleavage procedure for t-butoxycarbonyl (Boc) based solid phase peptide synthesis is reported. First the protective groups are removed from 4-(oxymethyl)-phenylacetamidomethyl (PAM) resin attached peptide with the weak hard acid, trimethylsilyl bromide-thioanisole/trifluoroacetic acid (TFA). In the second step, the peptide is cleaved from the resin with a stronger hard acid such as trimethylsilvl trifluoromethanesulfonate in TFA or with HF. The method is also shown to deformylate Nin-formyltryptophan moiety efficiently. The usefulness of this procedure for practical solid phase peptide synthesis is demonstrated by comparison with other deprotection methods in the synthesis of urotensin II and human endothelin. 相似文献
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MOTOYOSHI NOMIZU TAKANORI IWAKI TAKEYOSHI YAMASHITA YOSHIMASA INAGAKI KATSUHIKO ASANO MIKI AKAMATSU TOSHIO FUJITA 《Chemical biology & drug design》1993,42(3):216-226
One hundred Suc-X-Y-Ala-pNA peptides (SUC: succinyl, pNA: p-nitroanilide, X, Y: Gly, Ala, Val, Leu, Ile, Phe, Pro, x-aminobutyric acid, norvaline, norleucine) were synthesized and their reaction constants with porcine pancreatic elastase (Km, Kcat and Kcat/Km) were determined. These reaction constants were quantitatively analyzed using the Free–Wilson/Fujita–Ban method. The contribution of amino acid side chains to the reaction constants Km, Kcat and Kcat/Km), expressed logarithmically, was found to be additive. On the other hand, 19 elastase inhibitors of the general formula CF3CO-X-Y-Ala-pNA (X,Y: ten amino acids) were synthesized, and their inhibition constants were compared with the Michaelis constant for the corresponding substrates and analyzed using free-energy-related substituent constants. In the analysis of amino acid side chains in the Y position, the Ki value of the inhibitor was generally correlated to the Km value of the substrate, which corresponded to the inhibitor, thus confirming the validity of the equation This study may serve as a prototypical approach to unraveling structure–activity relationships of peptide substrates and inhibitors of medicinal or agricultural importance. 相似文献
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The patterns of sequential fluctuation of serum alpha-fetoprotein levels were analysed in 218 patients with liver cirrhosis in whom the serum alpha-fetoprotein levels were regularly and serially measured for more than 1 year. In the group of patients with persistently abnormal high values (greater than 50 ng/mL) over a follow-up period of more than 1 year, the incidence of the subsequent development of hepatocellular carcinoma was statistically and significantly higher (44%) compared to the other groups which showed normal (less than 20 ng/mL) or low abnormal levels (21-50 ng/mL) (16%), and transient abnormal high levels (greater than 50 ng/mL for a period of less than 1 year, mostly within 5 months) or fluctuated repeatedly between normal and transient abnormal high levels (23%). Hepatocellular carcinoma developed in 48 patients more than 2 years after the diagnosis of liver cirrhosis, and the fluctuating patterns of serum alpha-fetoprotein levels were analysed in these patients. The serum alpha-fetoprotein levels in 10 of these 48 patients stayed below 50 ng/mL until about 2.0-10.0 months before the detection of hepatocellular carcinoma and then increased steadily until the time of hepatocellular carcinoma detection. In these 10 patients, the monthly increasing ratios were approximately 1.6-4.8 times the previous values. 相似文献
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Induction of the immune response to periodontopathic bacteria and its role in the pathogenesis of periodontitis 总被引:2,自引:0,他引:2
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