One of the fundamental problems in drug design is the identification of a potential ligand docking site. The binding site of a competitive inhibitor is a substrate binding cavity, in the case of a non-competitive inhibitor, it is necessary to identify a cavity with a potential ligand interaction. In both cases, it is very important to know the characteristics of the complexing site. The knowledge of the structure and properties of substrate binding cavity allows to determine the optimal molecule capable of anchoring in a given cavity. In this work, these characteristics are determined by the hydrophobicity distribution. The model called fuzzy oil drop in its modified form (taking into account the environment other than water) was used to analyze the representatives of the subclasses of the lyase enzyme. Environmental characteristics and complexing properties of the six classes of these enzymes were analyzed. The use of fuzzy oil drop model has been shown to be suitable for the identification of substrate binding cavity for the E.C.4 enzyme class. The presented results may be extended to any other protein molecule in search for local discordance of hydrophobicity in respect to the idealized one representing the micelle-like distribution (centric hydrophobic core with a polar surface). This is why especially the residues representing local deficiency of hydrophobicity can be identified as creating cavity, where the potential ligand can be docked. This is why the presented model can be applied to in silico drug design.