Engineering starter units

Long, P.F., Wilkinson, C.J., Bisang, C.P. et al. (2002) Engineering specificity of starter unit selection by the erythromycin-producing polyketide synthase. Molecular Microbiology, 43, 1215. 

Hutchison (Ref 5a) discusses in detail the use of EtN in liq rocket propints. The use of EtN is not recommended as a means of operating aero engine starters, or for any other operations where the unit is to be repeatedly used in close proximity to human life... 

Although cell-free synthesis of 6-dEB was achieved, kinetic studies demonstrated that the process was very inefficient [34], The low rate of biosynthesis was likely due to the fact that the association of the three DEBS proteins in vitro was suboptimal. To simplify in vitro synthesis and to facilitate mechanistic analysis, a truncated version of the erythromycin PKS was created. The protein, DEBS 1-TE, was engineered by relocating the thioesterase (TE) from the end of DEBS 3 to the terminus of DEBS 1 (Fig. 9a,b) [35], In vivo, this bimodular construct synthesizes two triketide lactone products, one derived from propionate as a starter unit, and the other from acetate. 

The starter unit represents an attractive site in the aromatic polyketide scaffold for introducing alternative chemical functionalities. Most aromatic polyketide synthases (PKSs) are primed by acetate through the decarboxylative condensation of malonyl-ACP. Nonacetate-primed PKSs have been sequenced and characterized. Precursor-directed biosynthesis and heterologous recombination of initiation and elongation modules have led to the engineered biosynthesis of completely new aromatic polyketide scaffolds containing novel starter units, as well as the regioselective modification of known aromatic polyketides. 

Most of the type II PKSs studied so far used acetate as a starter unit. The minimal PKS appears to have intrinsic starter unit specificity for acetyl CoA, which could also be derived by decarboxylation from malonyl CoA, at least in vitro [173,183, 184]. Little is known about how a type II PKS chooses a starter imit other than acetate. The biosynthesis of 13 and 14 in S. peucetius and Streptomyces sp. C5, and oxytetracycline in Streptomyces rimosus are known examples in which a type II PKS used propionyl CoA [84,153,163] and malonamyl CoA [152] as a starter unit, respectively. However, engineered PKSs consisting of the KSa/KSp pair from either the dps [163] or otc [152] cluster produced poiyketides exclusively with an acetate starter, reinforcing the notion that the minimal PKS has an intrinsic specificity for an acetate starter. At least for the biosynthesis of 13 and 14 the choice of the propionate starter unit has been shown to depend on dedicated subunits, in addition to the minimal dps PKS, and on the protein/protein interactions among all the subunits of the resulting PKS complex [84,153,163]. 

Aircraft engines Ceramic turbine nozzles in the APU (Auxiliary Power Unit Engine). Seals runners installed in different business jets such as Falcon, Citation and Learjet. Ceramic oil pump spacer enhance engine could start capability on APUs on Boeing 777 and 737 and all Airbuses. Cutter pins, which are used as a safety feature for air turbine starters. Ceramic wear indicator on Airbus APU starter brushes since 1997... 

Lead accumulators are used in various applications, such as starters of internal combustion engines, electric traction (forklifts, wheelchairs, etc.), power generation units (power plants, telephone exchange stations, railroads, hospitals, etc.). 

Early in the twentieth century, cars powered by storage batteries were quite common. About 35% of all cars registered at that time in the United States were battery powered. They were more convenient than vehicles with ICEs that had to be cranked to start the engine. The situation took a turn when an electric starter was patented in 1912 and was then widely introduced. This meant the practically complete displacement of electric cars by today s traditional ICE vehicles. Today, battery-powered vehicles are used only for transport within production plants and for certain home deliveries, such as milk products and mail. 

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