Our previous investigations showed that linear-dendritic block copolymers containing poly(ethylene glycol) and poly(benzyl ether) monodendrons can selectively bind to glycoprotein enzymes like Laccase. We used this phenomenon to investigate the enzyme-catalyzed oxidation of steroids in pure water. The human hormones 17β-Estradiol (EST) and Equilin (EQ) were chosen. The mechanism of the biotransformation was elucidated on a model compound - tetrahydronaphthol (THN), a building fragment common for both steroids. All the compounds studied have very limited solubility in water and previous attempts for their enzyme-catalyzed oxidation have been performed in biphasic aqueous systems containing organic solvents. Thus the reactivity of the enzyme is seriously limited lowering the conversion rate and yield and necessitating long oxidation times. Here we present a method, which drastically improves all parameters of the THN, EST and EQ oxidation. Significant enhancement of the rates of oxidation without the use of mediators was achieved, leading to 100% conversion (~80% final yield) in 2 hours for THN and 12 hours for EST/EQ, with no organic solvents required at any step of the reaction. The solid product formation suggests that the complex acts as a nano-reactor maintaining a continuous influx of starting material and steady product expulsion. In addition we were able to steer the reaction toward different products with change in concentrations and reaction times. It should be also noted, that the used polymer-enzyme complex can be recycled for further oxidations. In contrast, other amphiphilic linear-linear copolymers like poly(ethylene oxide)-block-poly(styrene) did not enhance the kinetic characteristics of the enzyme.