The structure and reactivity of Pt(6) particles in silicalite and the sodium and hydrogen forms of zeolite ZSM-5 were investigated by density functional theory. In the case of adsorption on the sodium form and silicalite, the interaction energy is 15 and 9 kcal/mol, respectively, and a negative charge appears on the metal cluster. In the channels of the hydrogen form, the energy of absorption of a metal particle increases to 45 kcal/mol and oxidized platinum species is formed. The formation of the active center on the zeolite H-form involves the interaction of the platinum particle with an acid site, resulting in the suppression of the acidity of the support. An alternative alkane conversion mechanism is proposed, which avoids the involvement of the acid sites. Predictability of the direction of transformation of alkanes adsorbed on metal particles is shown.