The streptolysin forming system, reported by Bernheimer, containing resting streptococcal cells, RNA, maltose, KH
2PO
4 and MgSO
4 was reexamined. It was found that the optimum concentration of potassium ions for streptolysin formation was much higher than that of phosphate ion, which led to the improvement of the streptolysin-forming system by the use of a mixture of KCl and NaH
2PO
4 in substitution for KH
2PO
4.
The process of streptolysin formation occurring in the modified system with a higher concentration of KCl proved to consist of three distinguishable phase: initial inhibition phase, production phase, and reduction phase. The manifestation and duration of these phases were influenced by the concentration of potassium ion and the pH of the reaction medium, the influences exerted by these being dependent on each other.
The mechanism of potassium-and pH-effect was discussed.
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