Promiscuity, stability and cold adaptation of a newly isolated acylaminoacyl peptidase

We report on the characterisation of a member of the acylaminoacyl peptidase family, the first isolated from bacteria. The enzyme was obtained from the psychrophilic bacterium Sporosarcina psychrophila and shows the typical features of cold adaptation (low T-m, optimal temperature of 40 degrees C, poor thermal stability). It was also tested for substrate specificity, effect of metals, temperature dependence and structure stability and revealed promiscuous catalytic activity on at least two chemically distinct substrates, with k(cat)/K-m values for ester hydrolysis and acylamino acids cleavage of 1.7 x 10(4) s(-1) M-1 and 6.2 x 10(3) s(-1) M-1, respectively. Despite some properties cannot be explained with current models, results report on the relevance of structural and catalytic properties for the successful adaptation to cold temperatures. (C) 2011 Elsevier Masson SAS. All rights reserved.