Mm. Ahsan et al., PURIFICATION AND CHARACTERIZATION OF THE FAMILY-J CATALYTIC DOMAIN DERIVED FROM THE CLOSTRIDIUM-THERMOCELLUM ENDOGLUCANASE CELJ, Bioscience, biotechnology, and biochemistry, 61(3), 1997, pp. 427-431
The Clostridium thermocellum endoglucanase CelJ contains two different
catalytic domains in a polypeptide, i,e., a subfamily E1 catalytic do
main and a family J catalytic domain [J. Bacteriol., 178, 5732-5740 (1
996)]. The family J catalytic domain (CDJ-CelJ) was produced by a reco
mbinant Escherichia coli and purified, The purified CDJ-CelJ gave a si
ngle band on SDS-polyacrylamide gel electrophoresis and the molecular
weight of this enzyme (60,000) was consistent with the value (60,333)
calculated from the DNA sequence, CDJ-CelJ hydrolyzed various cellulos
ic substrates, xylan, and lichenan but not p-nitrophenyl (PNP)-cellobi
oside, PNP-glucoside, or PNP-xyloside at all, CDJ-CelJ was active on A
vicel, a microcrystalline cellulose, and the specific activity of CDJ-
CelJ on Avicel (0,0078U/mg protein) was comparable to that of CelS, wh
ich is recognized as the most important catalytic subunit of the C, th
ermocellum, cellulosome, suggesting that CelJ is also an important cat
alytic subunit in the cellulosome of this bacterium, in addition to Ce
lS.