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70712023

新虫 (初入文坛)

[求助] 蛋白质组学

the rate of peptide hydrolysis is reduced if an acidic amino acid is placed next to the cleavage site ,or if a proline is positioned at the C-terminal side, of the trypsin side no cleavage will occur. 这段话是什么意思,为什么酸性氨基酸和脯氨酸在碳端胰蛋白酶酶切就很难发生呢?求解,这方面知识很薄弱~
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cpn

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【答案】应助回帖

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70712023: 金币+10, ★★★很有帮助, 谢谢! 2013-08-24 09:40:32
酸性氨基酸是酶切效率下降,Proline在酶切位点C端是直接不切,这两个还是有差别的。
以下来源自http://en.wikipedia.org/wiki/Trypsin
是由Trypsin和底物相互作用的机理决定的,如下,但是实际上,Proline在位点的C端就不切这样一个情况,是有争议的。另外酸性氨基酸的酶切效率下降,应该是可以从电荷的角度来解释的。酸性氨基酸,带的是negative charge。
The aspartate residue (Asp 189) located in the catalytic pocket (S1) of trypsins is responsible for attracting and stabilizing positively charged lysine and/or arginine, and is, thus, responsible for the specificity of the enzyme. This means that trypsin predominantly cleaves proteins at the carboxyl side (or "C-terminal side" of the amino acids lysine and arginine except when either is bound to a C-terminal proline.,[5] although large-scale mass spectrometry data suggest cleavage occurs even with proline.[6]
2楼2013-08-21 16:46:04
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