青霉素酰化酶的分离纯化课件.ppt

,青霉素酰化酶的分离纯化,青霉素青霉素是常见抗生素之一。来源于点青霉、产黄青霉等真菌。对革兰氏阳性菌的生长有抑制作用R-COHNCOoH青霉素,青霉素的分类R-COHNCOoH青霉素F:R为cH3CH2CH=cHCH2青霉素G为青霉素置R为0-CH青霉素KR为cH3(CH2)CH2青霉素FR为CH3(OCH2)2CE2青霉素v;R为-0CH2氨节青霉素,R为H羟氨卡吉霉素.R为H-gH,青霉素的代谢途径a-氨基己二酸半胱氨酸缬氨酸ACVSa-氨基己二酰半胱氨酰缬氨酸IPNS异青霉素NAT青霉素,AT是一系列不同的酶。不同的AT催化不同的酰基转移反应生成不同的青霉素添加苯乙酸相应的AT催化它与异青霉素N反应生成青霉素G添加苯氧乙酸时,相应的AT催化它与异青霉素N反应生成青霉素V,青霉素酰化酶1950年,日本科学家发现产黄青霉和米曲霉的菌丝可以分解青霉素得苯乙酸和另一种有机物(后被证实为6APA)经研究,这一反应由青霉素酰化酶催化除了丝状真菌外,一些细菌和酵母中也检测到青霉素酰化酶的活性,青霉素酰化酶的结构青霉素酰化酶的结构差异较大。大肠杆菌( Escherichia co/)青霉素G酰化酶有个a亚基和一个亚基球形芽胞杆菌(Bac s sphaericus)的青霉素酰化酶是一个四聚体,ArcG fromE coli(PDB 1PNK)(24. a-and B-subunits are shownctively. Catalytic BSer tresidue and Ca* ion are shown in red and green, respec,Fig. 5. Structure of the active heterodimer of PA-G fromA faecalis(PDB 3K3W) C-and B-subuniyellow and dark blue, respectively. Catalytic BSer1 redue and Cai* ion are shown in red and green, respectively Disulfide bond in B-subunit between residues Cys492and Cys525 in wild-type enzyme is shown in magentaInsert in right part of figure shows fixation of N-terminus ofa-subunit and C-terminus of b-subunit due to creation ofnew disulfide bond(shown in orange)after double muta-tion aQ3C/RP751c,催化的反应R-COHN,青霉素酰化酶H2NRCOoHCooH青霉素6-APA,