Mitomycin derivatives having the formula
wherein X is acyl, lower alkyl, alkoxycarbonyl aryloxycarbonyl or aralkoxycarbonyl;
Y is hydrogen or methyl;
Z is hydrogen, methyl, acyl or aryloxycarbonyl;
one of R₁ and R₂ represents carbamoyloxymethyl and the other represents hydrogen, or R₁ and R₂ together represent methylene, show antibacterial and antitumour activities.
具有以下式子的丝裂霉素衍生物
其中 X 是酰基、低级烷基、烷氧羰基芳氧羰基或芳氧羰基;
Y 是氢或甲基
Z 是氢、甲基、酰基或芳氧羰基;
R₁ 和 R₂ 中的一个代表氨基甲酰氧甲基,另一个代表氢,或 R₁ 和 R₂ 共同代表亚甲基,具有抗菌和抗肿瘤活性。
Compositions for in-situ active compound assembly
申请人:SCRIPPS CLINIC AND RESEARCH FOUNDATION
公开号:EP0603160A2
公开(公告)日:1994-06-22
A composition for chemically treating a target condition, existing at a microenvironment localized within an environment, with an active compound, the composition comprising precursor components which can conjugate covalently to form the active compound in situ, and for which the covalent conjugation is more favourable at the microenvironment of the target condition than in the surrounding environment. Disclosed examples include biologically-active compounds which are preferentially formed in the microenvironment of tumour cells.
Essential Role of the Donor Acyl Carrier Protein in Stereoselective Chain Translocation to a Fully Reducing Module of the Nanchangmycin Polyketide Synthase
作者:Xun Guo、Tiangang Liu、Zixin Deng、David E. Cane
DOI:10.1021/bi201768v
日期:2012.1.31
Incubation of recombinant module 2 of the polyether nanchangmycin synthase (NANS), carrying an appended thioesterase domain, with the ACP-bound substrate (2RS)-2-methyl-3-ketobutyryl-NANS_ACP1 (2-ACP1) and methylmalonyl-CoA in the presence of NADPH gave diastereomerically pure (25,4R)-2,4-dimethyl-5-ketohexanoic acid (4a). These results contrast with the previously reported weak discrimination by NANS module 2+TE between the enantiomers of the corresponding N-acetylcysteamine-conjugated substrate analogue (+/-)-2-methyl-3-ketobutyryl-SNAC (2-SNAC), which resulted in formation of a 5:3 mixture of 4a and its (2S,4S)-diastereomer 4h. Incubation of NANS module 2+TE with 2-ACP1 in the absence of NADPH gave unreduced 3,5,6-trimethyl-4-hydroxypyrone (3) with a K-cat of 4.4 +/- 0.9 min(-1) and a k(cat)/K-m of 67 min(-1) mM(-1), corresponding to a similar to 2300-fold increase compared to the k(cat)/K-m for the diffusive substrate 2-SNAC. Covalent tethering of the 2-methyl-3-ketobutyryl thioester substrate to the NANS ACP1 domain derived from the natural upstream PKS module of the nanchangmycin synthase significantly enhanced both the stereospecificity and the kinetic efficiency of the sequential polyketide chain translocation and condensation reactions catalyzed by the ketosynthase domain of NANS module 2.