title: The properties of transketolase from photosynthetic tissue.
abstract: Transketolase (E.C. 2.2.1.1.) has been partially purified from wheat (Triticum aestivum, cv. Sappo) and spinach (Spinacia oleracea) leaves. The fully-active enzyme is a tetramer of relative molecular mass (Mr) of 150 kMr requiring thiamin pyrophosphate for maximal activity, and dissociating into a 74 kMr dimer in its absence or in dilute solution. The chloroplastic transketolase (over 75% of the cellular total) is magnesium-stimulated but the cytosolic form is magnesium-insensitive. Both chloroplastic and cytosolic transketolase showed similar broad specificities towards several ketose phosphate substrates including fructose 6-phosphate and sedoheptulose 7-phosphate. Wheat and spinach leaf transketolases are not light-activated and closely resemble the yeast enzyme in many of their properties.
authors.affiliation: A.R.C. Research Group on Photosynthesis, Department of Botany, University of Sheffield, S10 2TN, Sheffield, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Murphy
authors.forename: D A
authors.initials: DA
authors.lastname: Walker