- Differences in PLP-Dependent Cysteinyl Processing Lead to Diverse S-Functionalization of Lincosamide Antibiotics
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Pyridoxal-5′-phosphate (PLP)-dependent proteins constitute one of the largest and most important families of enzymes in living organisms. These proteins participate in numerous biochemical processes, many of which have not been characterized, and transform substrates containing an amino group through various reactions that share aldimine as a common intermediate. Herein, we report that the PLP-dependent enzymes CcbF and LmbF, which are highly related in phylogenesis, process cysteine S-conjugated intermediates in different ways and associate with individual downstream enzyme(s) toward distinct S-functionalization of the lincosamide antibiotics celesticetin and lincomycin A. CcbF catalyzes an unusual conversion that involves decarboxylation-coupled oxidative deamination of the cysteinyl group during the formation of a two-carbon alcohol linker, whereas LmbF is responsible for β-elimination, followed by S-methylation to produce a methylmercapto group. The two tailoring routes are variable and exchangeable with each other, allowing for in vitro combinatorial biosynthesis of a number of hybrid lincosamide antibiotics, including the natural product Bu-2545. These findings demonstrate the wide diversity of PLP chemistry in enzymatic catalysis and its promising applicability in creation of new molecules.
- Wang, Min,Zhao, Qunfei,Zhang, Qinglin,Liu, Wen
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- Metabolic coupling of two small-molecule thiols programs the biosynthesis of lincomycin A
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Low-molecular-mass thiols in organisms are well known for their redox-relevant role in protection against various endogenous and exogenous stresses. In eukaryotes and Gram-negative bacteria, the primary thiol is glutathione (GSH), a cysteinyl-containing tripeptide. In contrast, mycothiol (MSH), a cysteinyl pseudo-disaccharide, is dominant in Gram-positive actinobacteria, including antibiotic-producing actinomycetes and pathogenic mycobacteria. MSH is equivalent to GSH, either as a cofactor or as a substrate, in numerous biochemical processes, most of which have not been characterized, largely due to the dearth of information concerning MSH-dependent proteins. Actinomycetes are able to produce another thiol, ergothioneine (EGT), a histidine betaine derivative that is widely assimilated by plants and animals for variable physiological activities. The involvement of EGT in enzymatic reactions, however, lacks any precedent. Here we report that the unprecedented coupling of two bacterial thiols, MSH and EGT, has a constructive role in the biosynthesis of lincomycin A, a sulfur-containing lincosamide (C8 sugar) antibiotic that has been widely used for half a century to treat Gram-positive bacterial infections. EGT acts as a carrier to template the molecular assembly, and MSH is the sulfur donor for lincomycin maturation after thiol exchange. These thiols function through two unusual S-glycosylations that program lincosamide transfer, activation and modification, providing the first paradigm for EGT-associated biochemical processes and for the poorly understood MSH-dependent biotransformations, a newly described model that is potentially common in the incorporation of sulfur, an element essential for life and ubiquitous in living systems.
- Zhao, Qunfei,Wang, Min,Xu, Dongxiao,Zhang, Qinglin,Liu, Wen
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- Preparation method of clindamycin hydrochloride impurities
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The invention relates to a preparation method of clindamycin hydrochloride impurities, which belongs to the field of medicines. The technical problem to be solved by the invention is that a method forefficiently preparing clindamycin hydrochloride impurities 7-epilincomycin and 7-epilincomycin hydrochloride reference substances is lacked in the prior art. The invention provides a preparation method of a clindamycin hydrochloride impurity intermediate shown as a formula II, which comprises the following steps: by using a compound shown as a formula I and R1COOH as raw materials, carrying out aMitsunobu substitution reaction for preparation, and adding amine and/or a nitrogen-containing aromatic heterocyclic compound into a reaction solution. The invention further provides a complete synthesis method of the 7-epilincomycin and the 7-epilincomycin hydrochloride. The complete synthesis method comprises the following steps: by taking lincomycin as a raw material, carrying out silicon protection group coating, selective deprotection, Mitsunobu substitution reaction and hydrolysis reaction to obtain the 7-epilincomycin, and further carrying out a chlorination reaction to prepare the 7-epilincomycin hydrochloride.
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Paragraph 0094; 0119; 0120; 0121; 0122; 0123
(2020/01/08)
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- Method for treating inflammation
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A method of treating inflammation comprising topical administration to mammals suffering from an inflammatory condition not associated with amicrobial component, employing selected antibiotics as the anti-inflammatory agent.
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