Department of Biochemistry and Biophysics, University of California, Davis, California 95616.
Plant Physiol. 1978 Mar;61(3):389-93. doi: 10.1104/pp.61.3.389.
Sucrose synthase was purified from 22-day-old maize (Zea mays L.) kernels to homogeneity by the successive steps of ammonium sulfate fractionation, gel filtration through a Sephadex G-200 column, and affinity chromatography on a UDP-hexanol-amino-agarose column. The degree of purification is 42-fold and the yield is over 80%. Polyacrylamide gel electrophoretic techniques, sedimentation velocity, and gel filtration studies revealed that the enzyme has identical subunits and could assume tetrameric, octameric, and other higher aggregated forms which are dependent on the ionic species and ionic strength of the solution. All of the enzyme forms exhibit catalytic activity but show differences in their specific activities. In most cases, the tetramer is the predominant form and has the highest specific activity. It is thus concluded that the tetramer could be the native form of the enzyme. The subunit protein has a molecular weight of 88,000 and a blocked NH(2) terminus which is not available to Edman degradation. Some general properties and the amino acid composition of the enzyme are also reported.
蔗糖合酶从 22 天的玉米（Zea mays L.）胚乳中通过分步的硫酸铵分级沉淀、葡聚糖凝胶 G-200 柱凝胶过滤和 UDP-己醇-氨基琼脂糖柱亲和层析进行纯化，达到纯品。其纯度为 42 倍，产率超过 80%。聚丙烯酰胺凝胶电泳技术、沉降速度和凝胶过滤研究表明，该酶具有相同的亚基，并且可以假定为四聚体、八聚体和其他依赖于溶液中离子种类和离子强度的更高聚合形式。所有的酶形式都表现出催化活性，但表现出不同的比活性。在大多数情况下，四聚体是主要形式，具有最高的比活性。因此可以得出结论，四聚体可能是酶的天然形式。亚基蛋白的分子量为 88000，氨基末端被封闭，无法进行 Edman 降解。还报道了该酶的一些一般性质和氨基酸组成。
