Fractal geometry provides a mathematical formalism for describing complex spatial and dynamical structures.Therefore the enzyme molecules with irregular and self-similar structure can be studied thoroughly based on the fractal theory.In this paper the principle of box-counting dimension was used to investigate the impact of temperature and inhibitor on the structural changes of global enzymes and active sites of enzymes.The results suggested that the fractal dimension of enzyme molecule was greater than the fractal dimension of its active site.With increasing temperature

the calculated box-counting dimensions of global enzymes and their active sites all increased

especially for active sites.When enzyme was combined to the inhibitor

the dimensions of global enzymes did not change obviously

while the dimensions of active sites all decreased

indicating the decline of complexity for active sites.