Novel enzyme-metal-organic framework composite for efficient cadaverine production

Cadaverine is an important precursor for the synthesis of nylon 5X, which is used for engineering plastics and fibers. L-lysine can be converted to cadaverine by lysine decarboxylases with high catalytic activity and selectivity. However, the pH sensitivity and non-recyclability impede the practical application of lysine decarboxylases for cadaverine production. In this study, lysine decarboxylase (LdcEt) was immobilized on the surface of the zirconium-based metal-organic framework material (MOF) UIO-66-NH2 via covalent linkage for the first time. Morphological and structural analysis of the enzyme-MOF composite (LdcEt@HIO-66-NH2) indicated that LdcEt was successfully immobilized on the surface of UIO-66-NH2. Meanwhile, LdcEt@HIO-66-NH2 showed higher catalytic efficiency and enzyme activity, broader pH and temperature reaction range than free LdcEt. Compared with free enzymes, LdcEt@HIO-66-NH2 could catalyze more cadaverine in 2 h at high-level substrate concentration (365.3 g L-1 ). Furthermore, LdcEt@HIO-66-NH2 can also be reused for 10 cycles. These results proved that the efficient enzyme-MOF composite LdcEt@HIO-66-NH2 has great potential for the large scale cadaverine production.