Wellington J E, Shaw J M, Walker G J
Institute of Dental Research, United Dental Hospital, Surry Hills, New South Wales, Australia.
Microbios. 1994;79(319):121-9.
The rate of growth of Streptococcus sobrinus was a major factor governing the activity of free dextranase and free dextranase inhibitor in continuous culture filtrates. Depending on the growth conditions, a variable proportion of dextranase and dextranase inhibitor was combined in a tightly bound enzyme-inhibitor (EI) complex. Dissociation of the EI complexes revealed that the total productivity (free + bound) of both the enzyme and the inhibitor increased with growth rate, and that the activities of the enzyme and inhibitor released from the EI complex greatly exceeded their free activities, when the dilution rate (D) was high (D, 0.45 h-1). At low growth rate (D, 0.05 h-1), all the enzyme was bound to the inhibitor, and no free dextranase could be determined in culture filtrates; by contrast, at high growth rate (D, 0.45 h-1), all the inhibitor was bound to dextranase in the active EI complex, leaving active dextranase but no free inhibitor.
在连续培养滤液中，远缘链球菌的生长速率是决定游离葡聚糖酶和游离葡聚糖酶抑制剂活性的主要因素。根据生长条件的不同，一定比例的葡聚糖酶和葡聚糖酶抑制剂会紧密结合形成酶-抑制剂（EI）复合物。EI复合物的解离表明，酶和抑制剂的总生产率（游离+结合）均随生长速率的增加而提高，并且当稀释率（D）较高（D = 0.45 h-1）时，从EI复合物中释放出的酶和抑制剂的活性大大超过其游离活性。在低生长速率（D = 0.05 h-1）时，所有的酶都与抑制剂结合，在培养滤液中无法检测到游离葡聚糖酶；相反，在高生长速率（D = 0.45 h-1）时，所有的抑制剂都与活性EI复合物中的葡聚糖酶结合，留下了活性葡聚糖酶，但没有游离抑制剂。
