Different Rates of Metabolism of Soybean Proteinase Inhibitors during Germination.
During germination, the content of the major Bowman-Birk proteinase inhibitor (BB-E) in the cotyledons of soybean (Glycine max [L.] Merrill cv. Fiskeby V) seeds decreases, becoming a minor form by the sixth day of germination. One of the three other minor species (BB-D) of this inhibitor in the dry seed increases to become the major form in six-day cotyledons. The other two minor species (BB-C and BB-F) also appear to decrease during germination, but at a slower rate compared to the original major inhibitor form BB-E. By 13 days of germination, no distinct Bowman-Birk inhibitor species can be discerned in the cotyledons. The content of the major Kunitz proteinase inhibitor (K-B) also decreases during germination, but much more slowly. One new form of the Kunitz inhibitor (K-A) becomes apparent by the sixth day. By the 13th day, the proportion of the main isoinhibitor to the late-appearing form is approximately two to one. This difference in the rates of disappearance and appearance of isoinhibitor species in the Bowman-Birk and Kunitz proteinase inhibitor classes suggests a differential metabolism of these two types of proteins and a possible difference in function in the soybean plant.
Tan-Wilson
A L
AL
Department of Biological Sciences and Center for Somatic-Cell Genetics and Biochemistry, State University of New York at Binghamton, Binghamton, New York 13901.
Rightmire
B R
BR
Wilson
K A
KA