Tagen Michael B, Beinfeld Margery C
Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, 136 Harrison Ave, Boston, MA 02111, USA.
Peptides. 2005 Dec;26(12):2530-5. doi: 10.1016/j.peptides.2005.05.006. Epub 2005 Jun 24.
Purified recombinant prohormone convertase 1 and 2 (PC1 and PC2) cleave a peptide containing cholecystokinin (CCK) 8 Gly Arg Arg and the carboxyl-terminal peptide liberating CCK 8 Gly Arg Arg. PC1 and PC2 also cleave purified pro CCK, liberating the amino terminal pro-peptide while no carboxyl-terminal cleavage was detected. Under the conditions of the in vitro cleavage assay, it appears that the carboxyl-terminal cleavage site of pro CCK is not accessible to the enzymes while this site is readily cleaved in a synthetic peptide. Additional cellular proteins that unfold the prohormone may be required to expose the carboxyl-terminal site for cleavage.
纯化的重组激素原转化酶1和2（PC1和PC2）可切割含胆囊收缩素（CCK）8甘氨酸-精氨酸-精氨酸的肽段，并释放出CCK 8甘氨酸-精氨酸-精氨酸的羧基末端肽段。PC1和PC2还可切割纯化的CCK原，释放出氨基末端前肽，但未检测到羧基末端的切割。在体外切割试验条件下，CCK原的羧基末端切割位点似乎无法被这些酶识别，而该位点在合成肽中很容易被切割。可能需要其他能够使激素原展开的细胞蛋白来暴露羧基末端切割位点。
