Title of article :
A psychrophilic leucine dehydrogenase from Sporosarcina psychrophila: Purification, characterization, gene sequencing and crystal structure analysis
Author/Authors :
Zhao، نويسنده , , Ying and Wakamatsu، نويسنده , , Taisuke and Doi، نويسنده , , Katsumi and Sakuraba، نويسنده , , Haruhiko and Ohshima، نويسنده , , Toshihisa، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2012
Pages :
8
From page :
65
To page :
72
Abstract :
Leucine dehydrogenase (LeuDH, l-leucine: NAD+ oxidoreductase, deaminating, EC 1.4.1.9) was screened in six psychrophilic bacteria, and the highest levels of enzyme activity were found in Sporosarcina psychrophila DSM 3. As the first LeuDH from a psychrophilic bacterium, the enzyme was purified to homogeneity and characterized. The protein had an octameric structure with identical 43-kDa subunits, giving a total molecular mass of about 340 kDa. The enzyme exhibited the highest activity at 50 °C and exhibited one-tenth of that activity even at temperatures as low as 0 °C. The enzyme lost no activity with incubation at temperatures lower than 40 °C for 40 min, but there was marked loss of activity with incubations at temperatures higher than 50 °C. The optimum pHs were 11 for deamination of l-leucine and 9 for amination of 4-methyl-2-oxopentanoate. The Km values for l-leucine and NAD+ at 20 °C were 0.65 and 0.015 mM, respectively. The catalytic properties of S. psychrophila LeuDH were similar to those of LeuDHs from Lysinibacillus sphaericus and Geobacillus stearothermophilus, except for its lower optimal reaction temperature and thermostability at low temperatures. Crystal structural analysis of S. psychrophila LeuDH showed the total structure to be similar to that of the L. sphaericus enzyme, except minor alterations reduced the hydrophobic interactions and hydrogen bonds within and between subunits.
Keywords :
Purification , psychrophile , Sporosarcina psychrophila , crystal structure , Leucine dehydrogenase , Gene sequence , characterization
Journal title :
Journal of Molecular Catalysis B Enzymatic
Serial Year :
2012
Journal title :
Journal of Molecular Catalysis B Enzymatic
Record number :
1717445
Link To Document :
بازگشت