L-lysinamidase from Cryptococcus laurentii 112. Purification and properties

The purified enzyme hydrolyzes the linear L-lysinamide and the cycle amide of L-lysine--L- alpha -amino- epsilon -caprolactam. The apparent relative molecular mass is 180,000. The enzyme consists of four subunits and the molecular mass of a single subunit was found to be 47,000. The coefficient of molecular sedimentation equals 8.3 S, the isoelectric point was determined to be pH 4.3. The enzyme is not a glycoprotein. p-Mercuribenzoate binds 10 SH-groups of the native enzyme molecule and 20 SH-groups in the presence of 0.7% SDS. pH optimum for the hydrolysis of L-lysine amides was observed to be 7.5-7.7. The enzyme is strictly dependent on Mn super(2+) and Mg super(2+). The kinetic parameters for the hydrolysis of L-lysinamide were K sub(m) = 3.8 mM and k sub(cat) = 3000 sec super(-1). For the hydrolysis of cyclic L-lysinamide K sub(m) = 4.8 mM and k sub(cat) = 2600 sec super(-1).