PURIFICATION AND CHARACTERIZATION OF SUCROSE-PHOSPHATE SYNTHASE FROM PROSOPIS-JULIFLORA

Sucrose-phosphate synthase (SPS) was purified 4200-fold from the leave s of Prosopis juliflora a and resulted in a final specific activity of 467 nkat mg(-1) protein. The M-r of the native enzyme was 443 by gel filtration. The activity was optimum at pH 7.5 in MOPS buffer. Kinetic data for the forward reaction and both products and dead end inhibiti on indicated that the enzyme reaction follows an ordered bi-bi mechani sm. Tile purified preparation of SPS was activated by glucose-6-phosph ate and inhibited by inorganic phosphate. Both had a large effect only on the K-m of UDPG with inorganic phosphate acting antagonistically t o glucose-6-phosphate. The enzyme was inhibited by anions and activate d by 25 mM MgCl2,. The enzyme showed marginal sensitivity to -SH reage nts, and the activity could be restored with DTT. (C) 1997 Published b y Elsevier Science Ltd.