For so doing, we have chosen CYP450BM3, CYP450BSβ, , and CYP450OleT as model systems since they catalyze similar fatty acids but possess entirely different reactivity patterns. For instance, in the CYP450BM3 the fatty acid enters the active site via its hydrophobic tail part which lies above the heme plane. The presence of an alkyl substrate tail and F87 residue in the heme cavity makes the reaction center of CYP450BM3 hydrophobic (cf. Figure ). In contrast, the fatty acid enters the heme cavity in CYP450BSβ and CYP450OleT via its carboxylate end and interacts with the guanidinium group of R242/245 (CYP450BSβ/CYP450OleT) close to the active site, (cf. Figure ), which produces a more polar environment vis-à-vis CYP450BM3.