Premium
Microscopic rate‐constants for substrate binding and acylation in cold‐adaptation of trypsin I from Atlantic cod
Author(s) -
Ásgeirsson Bjarni,
Cekan Pavol
Publication year - 2006
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2006.07.043
Subject(s) - gadus , atlantic cod , chemistry , acylation , trypsin , dissociation constant , reaction rate constant , substrate (aquarium) , dissociation (chemistry) , hydrolysis , enzyme , catalysis , kinetics , stereochemistry , biochemistry , organic chemistry , biology , ecology , fishery , physics , receptor , quantum mechanics , fish <actinopterygii>
Temperature imposes limits on where life can thrive and this is evident in the evolution of the basic structural properties of proteins. Cold‐adaptation of enzymes is one example, where the catalytic rate constant ( k cat ) is increased compared with hot‐acclimated homologous under identical assay conditions. Trypsin I from Atlantic cod ( Gadus morhua ) has catalytic efficiency ( k cat / K m ) for amide hydrolysis that is 17‐fold larger than observed for bovine trypsin. Here, the individual rate‐constants for association of substrate ( k 1 ), dissociation of substrate ( k −1 ), and acylation of the enzyme ( k 2 ) have been determined using benzoyl‐Arg‐ p ‐nitroanilide or benzyloxycarbonyl‐Gly‐Pro‐Arg‐ p ‐nitroanilide as substrates. Rather unexpectedly, by far the largest difference (37‐fold increase) was observed in k 1 , the rate constant for binding of substrate. The cold‐adaptation of the dissociation and catalytic steps were not as prominent (increased by 3.7‐fold). The length of substrate did have an effect by increasing the reaction rate by 70‐fold, and again, the step most affected was the initial binding‐step.