Characterization of cold- and high-pressure-active polygalacturonases from a deep-sea yeast, Cryptococcus liquefaciens strain N6.
A deep-sea yeast, Cryptococcus liquefaciens strain N6, produces two polygalacturonases, p36 and p40 (N6-PGases). These N6-PGases were highly active at 0-10 degrees C in comparison to a PGase from Aspergillus japonicus. The hydrolytic activity of these N6-PGases remained almost unchanged up to a hydrostatic pressure of 100 MPa at 24 degrees C with a very small activation volume of -1.1 ml/mol. At 10 degrees C, however, the activation volume increased to 3.3 or 5.4 ml/mol (p36 and p40, respectively), suggesting that the enzyme-substrate complexes can expand at their transition states. We speculate that such a volume expansion upon forming the enzyme-substrate complexes contributes to decreasing the activation energy for hydrolysis. This can account for the high activity of N6-PGases at low-temperature.
Abe
Fumiyoshi
F
Extremobiosphere Research Center, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan. abef@jamstec.go.jp
Minegishi
Hiroaki
H
Miura
Takeshi
T
Nagahama
Takahiko
T
Usami
Ron
R
Horikoshi
Koki
K
D003080:Cold Temperature; D003454:Cryptococcus / Q000145:classification* / Q000201:enzymology*; D004789:Enzyme Activation; D006868:Hydrolysis; D007700:Kinetics; D009792:Oceans and Seas; D010368:Pectins / Q000378:metabolism; D011096:Polygalacturonase / Q000378:metabolism*; D011312:Pressure; D012623:Seawater / Q000382:microbiology*
D010368:Pectins; D011096:Polygalacturonase; C003181:polygalacturonic acid