Biofuels in Perspective

142 Biofuels
(a)
34 kDa
31 kDa
34 kDa
31 kDa
31 kDa
(b)
34 kDa
31 kDa
34 kDa
31 kDa
31 kDa
Cultivation time (h)
24 48 72 96 120
Cultivation time (h)
24 48 72 96 120
Culture medium
Cell wall
Membrane
Culture medium
Cell wall
Membrane
Figure 8.12 Western blot analysis of Rhizopus oryzae lipase extracted from culture medium, cell wall,
and membrane. Rhizopus oryzae cells were cultivated in (a) suspended and (b) immobilized cell cultures.
Basal medium without oils and fatty acids was used for cultivation. Fifteen microliters of the lipase solution
in each cellular fraction was subjected to SDS-PAGE electrophoresis. (From Ref. 56, with permission of The
Society for Biotechnology, Japan.)
sequence at amino acids –30 to –29 from its C-terminus, which is a kexin-like protease
recognition site. 58 The N-terminal sequence of ROL34 was identical to the sequence of the
precursor between residues 97 and 101, and that of ROL31 to the N-terminal 5-amino-acid
sequence of the mature region. It was thus concluded that the processing at a C-terminal
site of the Lys–Arg sequence produced ROL34, while ROL31 is the mature lipase given
by cleavage of the N-terminal 28-amino-acid residue of ROL34.
Figure 8.13 Schematic representation showing precursor and processing site of ROL. After cleavage of
the pre region, two patterns of processing occur in the pro region. First, the processing at a C-terminal site
of the Lys–Arg sequence produces ROL34. Second, the complete cleavage of the pro region gives mature
lipase with a molecular mass value of 31 kDa (ROL31). In the secretory pathway, ROL34 is localized in the
cell wall and easily secreted into the culture medium, while ROL31 is tightly bound to the cell membrane.
(From Ref. 56, with permission of The Society for Biotechnology, Japan.)