CRYSTALLIZATION OF 3 FORMS OF BAKERS-YEAST TRANSKETOLASE

Three forms of transketolase with differing thermal stability and affi nity for phosphocellulose have been found in baker's yeast. They have identical mobility in sodium dodecyl sulfate electrophoresis. Particul ar transketolase forms from yeast, pig and rat liver, and different ra bbit organs are similar in their thermal stability and chromatographic behavior. The relative amounts of the isoforms appear to depend on th e physiological state of the organism. Single crystals of the three pu re forms were grown using ammonium sulfate precipitation and found to differ morphologically and in stability during storage. The possibilit y of interconversions between the enzyme forms is discussed.