Contribution of Inosinic Acid to the Activation of Diphosphothiamine in Liver-Pyruvate Oxidase System

Abstract

It is well known that the enzymatic formation of diphosphothiamine (DPT) takes place with adenosine triphosphate (ATP) as a phosphorylating agent. K. Lohmann and P. Schuster (1) first found that the extracts of the brain and other tissues could serve as the sources of the specific transphosphorylating enzymes. F. Leuthardt and H. Nielsen (2) repeated the experiments and demonstrated the conversion of thia mine to DPT in many animal tissues and microorganisms with participation of ATP. K. H. Kiessling (3) observed yeast cells to convert thiamine to mono-and tripho sphothiamine, neither of which alone had cocarboxylase activity However, Rossi Fanelli (4) showed the pure triphosphothiamine isolated from yeast to be able to activate rat-liver pyruvate oxidase system similarly to DPT. N. Shimazono (5) de monstrated more enzymatic formation of DPT by yeast enzyme at certain pH levels when inosine or guanosine-triphosphate was added in place of ATP. He also found the latter triphosphates to be replaceable by inosine-monophosphate (IMP) plus ATP or guanosine-monophos phate plus ATP. No further investigation on the acti

The influence of inosine on the size of myocardial ischaemia and myocardial metabolism in the pig*

“…In the experiments of Jones & Mayer (1980) myocardial oxygen consumption did increase during inosine infusion in dogs, but an increase in myocardial blood flow was far greater than expected for such an increase in myocardial oxygen consumption. It has also been suggested that inosine may increase the activity of oxido-reductive enzymes (Maekawa et al, 1961 ;Sugahara, Suzuki, & Sahashi 1965) participating in tissue respiration, and improve tissue oxygenation by increasing 2,3-diphosphoglycerate in erythrocytes (Proctor, Fry & Lennon, 1974;Dawson, 1976). Thomas & Jones (1979) showed that although inosine enhanced contractility of both ischaemic and non-ischaemic myocardium, the content of high energy phosphates in these hearts remained unchanged.…”

“…Thomas & Jones (1979) showed that although inosine enhanced contractility of both ischaemic and non-ischaemic myocardium, the content of high energy phosphates in these hearts remained unchanged. It has also been suggested that inosine may increase the activity of oxido-reductive enzymes (Maekawa et al, 1961 ;Sugahara, Suzuki, & Sahashi 1965) participating in tissue respiration, and improve tissue oxygenation by increasing 2,3-diphosphoglycerate in erythrocytes (Proctor, Fry & Lennon, 1974;Dawson, 1976).…”

Possible Metabolism of in Sinic Acid for the Activation of Liver-Pyruvate Oxiase System Relating to Thiamine Diphosphate

“…In the previous paper (2), the effect of inosinic acid on the activation of thiamine diphosphate (TDP) in liver-pyruvate oxidase system was studied, and the increase in the activity of the enzyme system was confirmed by addition of inosinic acid (IMP) or adenosine triphosphate (ATP) in vitro.…”