N-Boc-4-亚甲基-L-脯氨酸甲酯 N-Boc-4-m

环肽的合成方法

反应。几乎所有可用于偶联反应的活泼酯都可用于合成环肽，主要有对硝基酚酯、N-羟基琥珀酰亚胺酯、五氟苯酯和2，4，5-三氯苯酚酯。线性多肽的C端羧基与对硝基酚、N-羟基琥珀酰亚胺、五氟苯酚或2，4，5-三氯苯酚，在DCC或其他缩合剂存在下，于低温反应，很容易得到相应的活泼酯。这种N端通常带有BOC或Z保护的活泼酯在酸性条件下脱去保护基，形成活泼酯的氢卤酸盐，在弱碱性稀溶液中，如在吡啶，DMF或二氧六环一类介电常数较大的溶剂中，保持pH8～9，加热（60～100℃）或室温搅拌数小时至数日，最终可得到环肽

Enzymes Acting on d-Amino Acid Containing Peptides

aminopeptidase and endopeptidase activities. The enzyme was active toward (d -Phe) n , Boc-(d -Phe) n , (d -Phe) n methyl ester, d -Phe-NH2 , Boc-(d -Phe) n methyl ester, and Boc-(d -Phe) n tert -butyl ester, but not toward (d -Ala) n (n = 2–4), (d

Determination of Sulfur Amino Acids, Glutathione, and Related Aminothiols in Biological Samples by Gas Chromatography with Flame Photometric Detection

and lack sensitivity. GC methods based on the conversion into trimethylsilyl (4 ,5 ), neopentylidine (6 ), and N-trifluoroacetyl n -butyl ester (7 ) derivatives lack sensitivity, gives a tailing peak and requires anhydrous derivatization conditions