Identification and isolation of methionine-cysteine rich proteins in soybean seed.
We recently developed a method to identify methionine-containing proteins and quantitate their methionine contents. We applied this method to soybeans and identified relatively methionine-rich proteins (MRP) among the albumins. By acidic methanol extraction of the albumins, we obtained a group of low molecular weight methionine-cysteine rich proteins (MCRP) that analyzed 4.0% methionine and 8.8% cysteine. MCRP made up 1-2% of the total protein in soybeans. Reversed-phase HPLC purification of MCRP yielded a protein peak that exhibited a single major band on denaturing polyacrylamide gel electrophoresis, had a molecular weight of 16 kD and contained 6.2% methionine and 18.8% cysteine. We are cloning the gene for this protein. Increasing its level through genetic engineering could increase the methionine-cysteine content of soybeans.
Kho
C J
CJ
Department of Nutritional Sciences, University of California, Berkeley 94720.
de Lumen
B O
BO
D000596:Amino Acids / Q000032:analysis; D002853:Chromatography, Liquid; D003545:Cysteine / Q000032:analysis*; D008715:Methionine / Q000032:analysis*; D014674:Plant Proteins, Dietary / Q000302:isolation & purification*; D030262:Soybean Proteins; D013025:Glycine max / Q000032:analysis*
D000596:Amino Acids; D014674:Plant Proteins, Dietary; D030262:Soybean Proteins; D008715:Methionine; D003545:Cysteine