Several alkyl-substituted methoxysilanes were evaluated as potential activity and stability enhancing agents for biomimetic silicification of Rhodosporidium toruloides d-amino acid oxidase (RtDAO). When methyl-substituted silanes along with tetramethoxysilane were used as silicic acid precursors for polyallylamine (PAA)-or R5 peptide-catalyzed silicic encapsulation, the RtDAO activity increased with the degree of substitution and the molar ratio up to 15 % of methyl-substituted silanes added. In the presence of 15 mol% trimethylmethoxysilane, the specific activities of encapsulated RtDAO catalyzed by PAA and R5 increased by 1.4- and 4.8-fold, respectively. For PAA-catalyzed encapsulation, a 2.4-fold increase occurred with 30 mol% n-propyltrimethoxysilane; this modification increased the T (m) value by 10 A degrees C and gave a threefold longer half-life in the presence of 10 mM H2O2 as compared to the encapsulation using tetramethoxysilane only.