24СʱÈÈÃŰæ¿éÅÅÐаñ    

²é¿´: 1195  |  »Ø¸´: 4
µ±Ç°Ö»ÏÔʾÂú×ãÖ¸¶¨Ìõ¼þµÄ»ØÌû£¬µã»÷ÕâÀï²é¿´±¾»°ÌâµÄËùÓлØÌû

Фäì

ľ³æ (СÓÐÃûÆø)

[ÇóÖú] ¹ØÓÚÎÄÏ×Öеľä×Ó¿´²»Ã÷°×£¬Çó·ÖÎö

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.
ÆäÖÐÁ½¾äÖÐÓÐÁ½¸öby£¬ÓÐЩŪ²»Ã÷°×£¬Õâ¾ä×ÓÊÇʲôÒâ˼£¬Çó·ÖÎö£¬×îºÃÄܹýдÇå³þ¾ä×ӽṹ¡£Ð»Ð»ÁË
»Ø¸´´ËÂ¥

» ²ÂÄãϲ»¶

» ±¾Ö÷ÌâÏà¹Ø¼ÛÖµÌùÍÆ¼ö£¬¶ÔÄúͬÑùÓаïÖú:

ÀíÂÛ¼ÆËã
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

wmjiang

Òø³æ (СÓÐÃûÆø)

¡¾´ð°¸¡¿Ó¦Öú»ØÌû

¼ÓformedÊÇ¿ÉÒÔÈ¥ÕâÑùÀí½â¡£
ºóÃæÒâÒåµÄÀí½â£¬Äã×Ô¼º¿´°É£¬ÎÒ²»ÊÇ»¯Ñ§×¨ÒµµÄ£¬Ã»ÄãÊìϤ
5Â¥2012-09-03 17:09:30
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû
²é¿´È«²¿ 5 ¸ö»Ø´ð

wmjiang

Òø³æ (СÓÐÃûÆø)

¡¾´ð°¸¡¿Ó¦Öú»ØÌû

£¨1£©They proposed a mechanism of catalysis that involves nucleophilic attack of the active site cysteine ¡¾that is aided by stabilization of the tetrahedral intermediate¡¿ ¡¾ formed by an oxyanion hole formed from the backbone amides of Cys159 and Ala155 (AbPncA numbering)¡¿.
ÓÐÈËÌá³öÁËÒ»¸ö»îÐÔλµãcysµÄÇ׺˹¥»÷µÄ´ß»¯»úÀí£¬ÓÉËÄÃæÌåÖмäÎïµÄÎȶ¨À´¸¨ÖúÇ¿»¯£¬Õâ¸öËÄÃæÌåÖмäÎï¾ÍÊÇCys159 and Ala155 ÖмäµÄ¹Ç¼ÜÐγɵÄÑõÀë×ÓѨ¶øÀ´µÄ¡£
£¨2£©
Water is then activated by proton abstraction ¡¾by Asp16 for nucleophilic attack on the covalent acyl-enzyme intermediate¡¿ to yield a thiolate and nicotinic acid.
ÔÚAsp16É϶Թ²¼Ûõ£»ùøÖмäÎï½øÐÐÇ׺˹¥»÷Ëù²úÉúµÄÖÊ×ÓÎüÊÕÄܹ»¼¤»îË®£¬´Ó¶ø²úÉúÁò´¼ÑκÍÑÌËá
2Â¥2012-09-03 13:55:49
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

wmjiang

Òø³æ (СÓÐÃûÆø)

¡¾´ð°¸¡¿Ó¦Öú»ØÌû

£¨1£©formed by an oxyanion hole ÔÚÇ°Ãæ²¹¸öformed¾ÍºÃÀí½âÁË
£¨2£©by proton abstraction ÊDZ»¶¯Óï̬µÄby£¬Òâ˼ÊÇË®±»ÖÊ×ÓÎüÊÕ¼¤»î£»
     by Asp16 for nucleophilic attackÖÐbyʱ½é´Ê£¬Í¨¹ý¶Ô16ºÅλµÄÌ춬°±ËáµÄÇ׺˹¥»÷
3Â¥2012-09-03 14:00:59
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

Фäì

ľ³æ (СÓÐÃûÆø)

ÒýÓûØÌû:
2Â¥: Originally posted by wmjiang at 2012-09-03 13:55:49
£¨1£©They proposed a mechanism of catalysis that involves nucleophilic attack of the active site cysteine ¡¾that is aided by stabilization of the tetrahedral intermediate¡¿ ¡¾ formed by an oxyanion h ...

ллͬѧ¡£µ«»¹ÊDz»Ì«Ã÷°×£¬ÎªÊ²Ã´¾ÍÒªÔÚÇ°ÃæÓÐÒ»¸öformed¡£Ã»Óиù¾Ý°¡¡£
ÔÙ¾ÍÊÇproton abstraction Ó¦¸ÃÊÇ¡°È¥ÖÊ×Ó×÷Óá±µÄÒâ˼¡£
ÁíÍ⣬for nucleophilic attack on the covalent acyl-enzyme intermediate Õâ¸öÓ¦¸ÃÊÇË®·Ö×Ó±»¼¤»îµÄÄ¿µÄ°É£¬¶ø²»ÊÇÄã˵µÄAsp16¶Ôcovalent acyl-enzyme intermediateµÄ½ø¹¥°É¡£ÕâÊÇÎÒµÄÀí½â¡£
ллÁË£¡
ÀíÂÛ¼ÆËã
4Â¥2012-09-03 15:59:17
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû
×î¾ßÈËÆøÈÈÌûÍÆ¼ö [²é¿´È«²¿] ×÷Õß »Ø/¿´ ×îºó·¢±í
[¿¼ÑÐ] ÊÛSCIÒ»ÇøT0PÎÄÕ£¬ÎÒ:8.O.55.1.O.5.4,¿ÆÄ¿È«,¿É+¼± +3 7K1CJE38xLG4 2026-08-25 4/200 2026-08-26 02:04 by cNXvBfCpiZOM
[ÂÛÎÄͶ¸å] ÊÛSCIÒ»ÇøT0PÎÄÕ£¬ÎÒ:8O.55.1.O.5.4,¿ÆÄ¿ÆëÈ«,¿É+¼± +3 7K1CJE38xLG4 2026-08-25 4/200 2026-08-26 02:04 by cNXvBfCpiZOM
[»ù½ðÉêÇë] ÔÚ¼á±ù»¹¸Ç×ű±º£µÄʱºò£¬ÎÒ¿´µ½ÁËÅ­·ÅµÄ÷»¨¡£ (½ð±Ò+10) +6 ziyangfang 2026-08-25 9/450 2026-08-25 20:26 by huagongfeihu
[»ù½ðÉêÇë] ijЩ»ú¹¹£¬ÒÔЧÂʵÍΪÈÙ£¬ÒÔЧÂʵÍ×÷Ϊ´æÔڸР+9 yuleib84 2026-08-25 10/500 2026-08-25 17:14 by alexon
[»ù½ðÉêÇë] 2026¹ú×ÔÈ»º¯ÆÀ·Ñµ½ÕË +20 ÑòÑü°å 2026-08-21 23/1150 2026-08-25 16:34 by zsna
[»ù½ðÉêÇë] ½ñÈÕ²»·Å°ñ£¿Íø´«¹ú×ÔȻԤ¼Æ 8 Ô 27 Èտɲé½á¹û +17 ҽѧÀÏÄк¢ 2026-08-20 22/1100 2026-08-25 15:36 by ҽѧÀÏÄк¢
[»ù½ðÉêÇë] Èç¹û´Ë¿ÌÄãÕýÔÚΪ¹ú»ù¸Ðµ½½¹ÂÇ£¬²»·ÁÀ´ÌýÌýÕâÊס¶»ù½ðÖ®Íâ¡· +8 scalable 2026-08-24 8/400 2026-08-25 12:52 by jnhyjjm
[»ù½ðÉêÇë] ûÓÐÈκÎÏûÏ¢-ÊDz»ÊǾÍÁ¹ÁË +9 ͼÀ²Í¼À² 2026-08-24 10/500 2026-08-25 11:59 by ÄϺ£Ð¡¸ç
[»ù½ðÉêÇë] ÈËÆø²»ÐÐÁË +11 fansofjerry 2026-08-21 11/550 2026-08-25 11:04 by ¹Â¶ÀµÄÓ¢ÐÛ6
[»ù½ðÉêÇë] 2026ÄêµÄ¹ú¼ÒÉç¿Æ»ù½ðÏîĿͨѶÆÀÉóµÄйæÔòÓëж¯Ïò¡¢ÐÂÌôÕ½ +5 process2012 2026-08-23 7/350 2026-08-25 09:42 by huixian257
[»ù½ðÉêÇë] ½ñÌì»ù½ð»á³ö½á¹ûÂð£¿20260819 +17 kkkl_v 2026-08-19 18/900 2026-08-25 09:41 by windflowerwy
[»ù½ðÉêÇë] ÎÒÃæÉÏÍêµ°ÁË +13 ÇÒÌý»¢Ð¥ 2026-08-20 14/700 2026-08-25 09:10 by mrkang
[»ù½ðÉêÇë] ·¶½øÖоÙÒ»ÎĵÄÖÐÐÄ˼Ïë +7 Ñ׻ƹóëÐ 2026-08-22 8/400 2026-08-25 08:48 by ZJTJZ
[»ù½ðÉêÇë] Ö»ÓÐÿÄêÕâÖÖʱºòÀ´¹ä¹äСľ³æ +25 yaoyewhu2008 2026-08-20 27/1350 2026-08-25 08:01 by Equinoxhua
[»ù½ðÉêÇë] ½¨Òé»ù½ð·¢²¼Ìáǰ¸ø³öÃ÷È·µÄʱ¼äµã +13 kulium 2026-08-21 16/800 2026-08-24 16:27 by superceng
[»ù½ðÉêÇë] ¿ÆÑй¶ùÌ«ÄÑÁË +18 ÎÒ4´ó°×²Ë 2026-08-20 19/950 2026-08-24 09:47 by ¿­¶÷¹ãÊ¢´ß»¯·ÖÎ
[½Ìʦ֮¼Ò] Ìø²ÛºóÔÚÑÐÏîÄ¿Ôõô°ì£¿ +5 ¼òµ¥»¯xn 2026-08-22 10/500 2026-08-23 12:38 by ¼òµ¥»¯xn
[»ù½ðÉêÇë] ½ñÌì·Å°ñÂ𣿠+15 ²¼²¼ºÍÒ»¶þ 2026-08-19 16/800 2026-08-23 09:55 by ÕÅ´ºÉú
[»ù½ðÉêÇë] Ó¦¸ÃÊÇÏÂÖÜÈý26ÈÕ¹«²¼Á˰ɣ¿ +4 ¹þ¹þ¸ò£¿ 2026-08-21 4/200 2026-08-21 10:58 by Vivilian
[»ù½ðÉêÇë] »ù½ð°¡»ù½ð +4 longfie172 2026-08-20 4/200 2026-08-21 08:58 by mark mao
ÐÅÏ¢Ìáʾ
ÇëÌî´¦ÀíÒâ¼û