Parfait R, Di Giambattista M, Cocito C
Biochim Biophys Acta. 1981 Jul 27;654(2):236-41. doi: 10.1016/0005-2787(81)90177-5.
When the S component of virginiamycin binds in vitro to the 50 S ribosomal subunit, a change of fluorescence intensity proportional to the amount of complex formed occurs. Erythromycin competes with virginiamycin S for attachment to ribosomes, and removes previously bound virginiamycin S from its target, as revealed by spectrofluorimetric analysis. The 50 S subunits which are incubated with the M component of virginiamycin (50 S*) have an increased affinity for virginiamycin S (the association constants of virginiamycin S with ribosomes are 2.5 x 10(6) M-1 in the absence of virginiamycin M, and 15 x 10(6) M-1 in its presence). Erythromycin does not compete with virginiamycin S for attachment to 50 S* subunits nor is it able to remove virginiamycin S previously bound to the 50 S* subunit. Thus, virginiamycin M produces a change in ribosomes, which results in a tighter complex virginiamycin S-50 S* subunit. Such change does not require the presence of virginiamycin M, however, as shown by the observation that ribosomes to which labeled virginiamycin M is transiently linked bind virginiamycin S in a form that cannot be removed by erythromycin.
当维吉尼亚霉素的S组分在体外与50S核糖体亚基结合时，会发生荧光强度的变化，该变化与形成的复合物的量成正比。红霉素与维吉尼亚霉素S竞争附着于核糖体，并从其靶标上移除先前结合的维吉尼亚霉素S，这通过荧光光谱分析得以揭示。与维吉尼亚霉素M组分（50S*）一起孵育的50S亚基对维吉尼亚霉素S的亲和力增加（在不存在维吉尼亚霉素M时，维吉尼亚霉素S与核糖体的缔合常数为2.5×10⁶M⁻¹，在其存在时为15×10⁶M⁻¹）。红霉素不与维吉尼亚霉素S竞争附着于50S亚基，也无法移除先前结合到50S亚基上的维吉尼亚霉素S。因此，维吉尼亚霉素M会使核糖体发生变化，从而导致维吉尼亚霉素S-50S*亚基形成更紧密的复合物。然而，如观察到与标记的维吉尼亚霉素M短暂连接的核糖体以红霉素无法移除的形式结合维吉尼亚霉素S所示，这种变化并不需要维吉尼亚霉素M的存在。
