Substrate specificity of Cryptococcus albidus and Eupenicillium erubescens α-L-rhamnosidases

摘要

The substrate specificity of Cryptococcus albidus and Eupenicillium erubescens α-L-rhamnosidases has been investigated. It is shown that the enzymes are able to act on synthetic and natural substrates, such as naringin, neohesperidin. α-L-Rhamnosidases hydrolysed the latter ones very efficiently, in this case E. erubescens enzyme was characterized by higher values of V submax/sub in comparison with the enzyme of C. albidus . However the C. albidus α-L-rhamnosidase showed greater affinity for naringin and neohesperidin than the enzyme of E. erubescens ( K subm/sub 0.77 and 3.3 mM and 5.0 and 3.0 mM, respectively). As regards the synthetic derivatives of monosaccharides, both enzymes exhibited narrow specificity for glycon: E. erubescens α-L-rhamnosidase – only to the p -nitrophenyl-α-L-rhamnopiranoside ( K subm/sub 1.0 mM, V submax/sub 120 μmol/min/mg protein), and C. albidus – to p -nitrophenyl-α-D-glucopyranoside ( K subm/sub 10 mM, V submax/sub 5 μmol/min/mg protein). Thus, it was found that the enzyme preparations of E. erubescens and C. albidus are differed by their substrate specificity. The ability of E. erubescens and C. albidus α-L-rhamnosidases to hydrolyse natural substrates: naringin and neohesperidin, evidences for their specificity for α-1,2-linked L-rhamnose. Based on these data, we can predict the use of E. erubescens and C. albidus α-L-rhamnosidases in various industries, food industry in particular. This is also confirmed by the fact that the investigated α-L-rhamnosidases were stable at 20% concentration of ethanol and 500 mM glucose in the reaction mixture.