送交者: Godfather 于 2006-1-22, 11:13:20:
回答: 链霉素残留也许对PH-SA的活性起稳定作用 由 桂铭 于 2006-1-22, 00:04:48:
1. Colicin Ia is also a basic protein (pI 10). It should not have ionic interaction with Streptomycin. As I said, unless there are other forces such as hydrophobic interaction, hydrogen binding, etc. Ia has a hydrophic domain (40 amino acids) at its C-termini, which is also the channel-forming functional domain, so there is a possibility of having hydrophobic interaction. However, if such interaction happened, then the complex would lose it channel-forming activity, which of course would be against the original idea for killing bacteria. If Streptomycin indeed can form complex with Colicins, it would be an interesting area to explore, which may lead to novel findings, even theory.
2. There have been no reports on the requirements for ions to maintain their functions or conformations of Colicins. Instead, in my opinion, inclusion ions would interfere with their interaction with membrane phospholipids to form the ion channels.
3. There are numerous MRSA strains depending on which ones you use for the test. Since Streptomycin is not a standard sgent to treat SA infection, it's highly possible that most clinical isolates of MRSA are not resistant to Streptomycin indeed. As I mentioned before, the antibacterial activity depends on what concentrations you test as well.