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肖瀟木蟲 (小有名氣)
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[求助]
關(guān)于文獻(xiàn)中的句子看不明白,求分析
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They proposed a mechanism of catalysis that involves nucleophilic attack of the active site cysteine that is aided by stabilization of the tetrahedral intermediate by an oxyanion hole formed from the backbone amides of Cys159 and Ala155 (AbPncA numbering). Asp16 was proposed to deprotonate Cys159 to initiate catalysis and to donate a proton to aid the release of NH3 during the tetrahedral intermediate collapse to form the thioester acyl intermediate. Water is then activated by proton abstraction by Asp16 for nucleophilic attack on the covalent acyl-enzyme intermediate to yield a thiolate and nicotinic acid. Transfer of a proton from Asp16 to the active site cysteine completes the catalytic cycle. 其中兩句中有兩個by,有些弄不明白,這句子是什么意思,求分析,最好能過寫清楚句子結(jié)構(gòu)。謝謝了 |

木蟲 (小有名氣)

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(1)They proposed a mechanism of catalysis that involves nucleophilic attack of the active site cysteine 【that is aided by stabilization of the tetrahedral intermediate】 【 formed by an oxyanion hole formed from the backbone amides of Cys159 and Ala155 (AbPncA numbering)】. 有人提出了一個活性位點(diǎn)cys的親核攻擊的催化機(jī)理,由四面體中間物的穩(wěn)定來輔助強(qiáng)化,這個四面體中間物就是Cys159 and Ala155 中間的骨架形成的氧離子穴而來的。 (2) Water is then activated by proton abstraction 【by Asp16 for nucleophilic attack on the covalent acyl-enzyme intermediate】 to yield a thiolate and nicotinic acid. 在Asp16上對共價(jià)酰基酶中間物進(jìn)行親核攻擊所產(chǎn)生的質(zhì)子吸收能夠激活水,從而產(chǎn)生硫醇鹽和煙酸 |
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