Succinic semialdehyde specific, NAD+ -dependent, Succinic semialdehyde Dehydrogenase from Sugarcane requires –SH group for activity and its gene resembles its rice counterpart

Gireesh Babu K.*, Naik G. R.

Abstract


Succinic semialdehyde dehydrogenase (SSADH), oxidizes Succinic semialdehyde produced by first two enzymes of a g-aminobutyric acid (GABA) shunt and links the shunt with TCA cycle. In the present study the biochemical properties of Saccharum officinarum L. (Var. Co 86032) were studied and the corresponding partial gene was isolated and sequenced. The sugarcane SSADH was purified by 6.9 folds and SDS-PAGE analysis revealed presence of ~45 kD protein, possibly a homomultimer. Biochemical characterization of Sugarcane SSADH is specific for SSA with 2.2 μM Km value. It displayed a broad activity range between pH 8.4-9.4 and found optimumly active at pH 8.8 and 9.0. Sugarcane SSADH was severely inhibited by thiol directed reagents and hence requires a SH group for catalytic activity and /or maintaining the active conformational structure of the enzyme.  Isolation of SSADH gene through cDNA yielded 1425 bp stretch of sequence, resembling its counterpart from rice.  Further analysis of deduced protein varied at characteristic positions of mature dehydrogenases, indicating a partial sequence.

Keywords


cDNA; aminobutyric acid; kinetic studies; Saccharum officinarum, Succinic semialdehyde dehydrogenase; purification.

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