The effects of biogenic phosphates on proteinase-induced protein cleavage and functioning of plasminogen activator

We showed, using the method of lysis of fibrin plates and five substrate proteins in a thin layer of agar gel, that inorganic orthophosphate (0.001–0.06 M) enhances by 50–250% the activatory functions of streptokinase, urokinase, and tissue plasminogen activator and, in general, by 1.2–12.0 times enhances protein lysis by trypsin, α-chymotrypsin, subtilisin, papain, bacterial metalloprotease, and even pepsin at a concentration < 4 mM. At higher concentrations, phosphate sharply inhibited pepsin activity and inhibited by 40–50% gelatin lysis by papain and gelatin (at a peak concentration) and casein lysis by metalloprotease. Inorganic pyrophosphate ions at concentrations of 10^?8–10^?1 M enhanced the cleavage of a number of proteins by serine proteinases and, at concentrations of 10^?5–10^?3 M, the activities of pepsin, plasminogen tissue activator, and streptokinase by 100 and 40%, respectively. The pyrophosphate concentrations of >10^?3 and >10^?4 M inhibited pepsinand metalloproteinase-catalyzed lysis of vritually all proteins. ATP increased casein lysis by serine proteinases, metalloproteinase, and pepsin by 20–60% at concentration of >10^?3 M and by 30–260% at 10^?2 M concentration. At concentrations of 10^?2 M, it inhibited the cleavage of some proteins by trypsin, chymotrypsin, papain, and metalloproteinase by 20–100%, and, at concentrations of 10^?3 M, lysis of albumin by pepsin and other proteins (except for fibrinogen) by metalloproteinase. A GTP concentration of 10^?7–10^?2 M increased protein degradation by serine proteinases, papain, and gelatin lysis by pepsin by 20–90%, whereas albumin lysis was inhibited by 40–70%. The presence of 10^?6–10^?5 M GTP led to a slightly increased degradation of hemoglobin and casein by bacterial metalloproteinase, while ≥10^?3 M GTP induced a drop in the activity of the metalloproteinase by 20–50%. ADP enhanced gelatin lysis by trypsin, casein lysis by pepsin and papain, and inhibited metalloproteinase activity by 20–100% (at ≥10^?3 M). Peculiarities of the effects of AMP and GD(M)P on gelatin lysis were found.