Detergent-Solubilisation of a Homogalacturonan Galacturonosyltransferase from Mung Bean

摘要: A membrane-bound enzyme [homogalacturonan 4—galacturonosyltransferase (HGA-GaIAT)] that catalyses the transfer of galacturonic acid onto homogalacturonan (HGA) component plant cell wall pectin has previously been identified and partially characterised in mung bean (Vigna radiata) seedlings (Villmez et al., 1965; Villmez 1966; Smith, 1999). This study reports successful detergent-solubilisation from microsomal membranes growing hypocotyl using a range detergents. Highest levels radioincorporation were obtained with detergent Zwittergent Z3–14 at concentration 1% 25 mM Tris-HC1 pH 7.0 manganese 5 mM. Under these conditions, polygalacturonic (PGA) as acceptor, activity solubilised by this was comparable detected intact particulate membranes. The soluble transferred small amount [14C]-galacturonic nucleotide precursor UDP-[14C]-galacturonic an endogenous acceptor enhanced addition exogenous methylated or non-methylated pectins. presence methyl groups on did not appear to influence enzyme. Oligogalacturonides [degree polymerisation (DP) = 6, 10, 13, 14 15] also radioincorporation, oligogalacturonide DP 15 being slightly more effective than others. Successful enabled partial purification HGA-GaIAT isoelectric focusing (IEF) results have revealed least two isoforms (pI~5 pI~6).