Selective Inhibition by Preparations of Streptococcal Filtrates of the Oxidative Metabolism of Mitochondria Procured From Rabbit Myocardium

Abstract

Myocardial contractile power diminishes rapidly when minute quantities of streptolysin O are perfnsed through the vigorously beating isolated hearts of guinea pigs, rabbits, and rats, as recent investigations have shown (1). From experiments undertaken to disclose more about this phenomenon it has now been learned that partially purified preparations of streptococcal filtrates containing streptolysin O will regularly inhibit the oxidative metabolism of mitochondria procured from the myocardium of rabbits when certain constituents of the citric acid cycle are employed as substrate, the finding suggesting that the activity of the coenzyme diphosphopyridine nucleotide (DPN) is in some manner altered. Also, the agent in the solutions which is responsible for this effect has been found to differ from streptolysin O in a number of important respects. Materials and MethodsPreparations of streptococcal filtrates containing streptolysin 0 were added to suspensions of mitochondria obtained from the myocardlum of rabbits, and the effect on oxygen consumption by the mitochondria was observed in the Warburg apparatus in the presence of a number of different substrates. Streptococcal Filtratea.--Preparations of streptococcal filtrates containing streptolysin Owere made from cultures of the C203S strain of group A streptococcus according to the method previously described (1). The solutions were dialyzed overnight prior to use, and were activated with equal parts of 1 per cent cysteine in all instances unless otherwise indicated. Four different batches, ranging in streptolysin O activity from 10,000 to 53,000 hemolytic units per ml., were employed in these studies, and the same results were obtained with each.

Studies on the Cardiotoxicity of Streptolysin O

“…Crude streptolysin contains DPNase, which acts by liberating nicotinamide from the molecule of DPN. It has been suggested by Carlson et al (1956) that DPNase may also have cardiotoxic properties, but these were not evident under our experimental conditions. Oxidized streptolysin Merieux contains no less than 44,520 units of DPNase/phial; the animal supported the intravenous injection of as much of this DPNase as 20,000 units/20 g without evident effect on the e.c.g., or on the auricular consumption of oxygen.…”

A simple biological method for detecting streptococcal nicotinamide adenine dinucleotide glycohydrolase.

“…It is nevertheless possible that more than one streptococcal product is involved. NADG inhibits the oxidation of citrate, fumarate, and cx-keto-glutarate by mitochondria (Carlson et al, 1956).…”

The NAD-glycohydrolase (nga) gene of Streptococcus pyogenes

“…Not all streptococcal species produce NAD-glycohydrolase and it is detected only in the culture ¢ltrates of human pathogenic streptococci (groups A, C and G) [11^13]. The biological function of streptococcal NAD-glycohydrolase is not well understood, though suggestions have been made that it plays a role in inhibition of the oxidative metabolism of mitochondria, leukotoxicity and phagocytosis [11,12]. Karasawa and co-authors have recently suggested that cADPR synthesized by streptococcal NAD-glycohydrolase may induce lymphocyte proliferation and cause disorders through cytokine networks [10].…”