Synthesis of diphytanyl ether analogues of phosphatidic acid and cytidine diphosphate diglyceride

The chemical synthesis of 2,3-di-O-phytanyl-sn-1-glycerophosphate was carried out in two ways: (a) by phosphorylation of 2,3-diphytanyl-sn-glycerol with diphenylphosphoryl chloride in pyridine, followed by catalytic hydrogenolysis of the phenyl groups; and (b) by condensation of 1-iodo-2,3-di-O-phytanyl-sn-glycerol with silver di-p-nitrobenzyl phosphate in anhydrous benzene, followed by catalytic hydrogenolysis of the p-nitrobenzyl groups. The free diether phosphatidic acid obtained was converted to the dipotassium and disodium salts. The diether phosphatidic acid was also converted to the diether analogue of cytidine diphosphate diglyceride by condensation with cytidine monophosphate morpholidate in pyridine. The physical properties of these diether analogues are described, as well as their stabilities towards acid hydrolysis.

Demonstration of acid phosphatase activity using 1-acetyl-3-indolyl phosphate as substrate

A simultaneous coupling azo-indoxyl method for the cytochemical demonstration of acid phosphatase activity using p-toluidine salt of 1-acetyl-3-indolyl phosphate is described. A satisfactory staining for the enzyme activity was obtained following incubation of formol-calcium-fixed frozen sections for 30 min at 25°C in a medium containing 1 mM each of the substrate and hexazonium pararosanilin and adjusted to pH 4.5-5.0 with acetate buffer. The distribution of acid phosphatase activity demonstrated by this method was identical with that obtained either by Gomori's technique using β-glycerophosphate as substrate or by the Barka and Anderson's naphthol AS-BI phosphate-hexazonium pararosanilin method in several tissues of male rats so far examined. However, the adrenal enzyme activity was most prominent in the medulla with 1-acetyl-3-indolyl phosphate and β-glycerophosphate but it was more marked in the cortex with naphthol AS-BI phosphate. An advantage of using 1-acetyl-3-indolyl phosphate as substrate is that the same compound can be used for comparing azo-indoxyl and lead-salt methods. Effects of phospholipase C and Triton X-100 on staining for acid phosphatase were tested by pretreating fixed rat liver and kidney sections with these agents and incubating them in the medium containing 1-acetyl-3-indolyl phosphate and either hexazonium pararosanilin or lead ions as a coupler. The pretreatment did not change discrete lysosomal staining, as seen in untreated controls, using pararosanilin as a coupler, but greatly modified the staining using lead ions. The results indicate that the preciseness of staining for acid phosphatase with lead-salt method is highly dependent on some lipid material which attracts lead in tissues and that appropriately devised azo dye or azo-indoxyl methods demonstrate enzyme sites more accurately than lead-salt method.

Synthesis of 2,3-diphosphono-DL-glyceric acid, a racemic analogue of 2,3-diphospho-D-glyceric acid, the cofactor of both phosphoglyceric acid mutase and hemoglobin

2,3-Diphosphono-DL-glyceric acid, a racemic phosphonic acid, analogue of 2,3-diphospho-D-glyceric acid, the cofactor of phosphoglyceric acid mutase and hemoglobin, has been synthesized. It was obtained by treating the methyl esters of either β-chlorolactic acid, β-bromolactic acid, or glyceric acid with triethyl phosphite at 140–145° for 48 h, hydrolyzing the major reaction product tetraethyl 2,3-diphosphono-DL-glyceric acid methyl ester with concentrated hydrobromic acid at 140° for 24 h, and isolating 2,3-diphosphono-DL-glyceric acid as pentabarium or tricyclohexylammonium salt. 2,3-Diphosphonoglyceric acid and 2,3-diphosphoglyceric acid are readily distinguished from each other by chromatographic and chemical as well as by spectroscopic methods.

Phosphoglycerate kinase: an X-linked polymorphism in man

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N-(5'-phosphoribosyl)anthranilate isomerase-indol-3-ylglycerol phosphate synthetase of tryptophan biosynthesis. Relationship between the two activities of the enzyme from Escherichia coli

Further evidence is presented to confirm the previous conclusion that the enzyme from Escherichia coli catalysing the two sequential reactions in tryptophan biosynthesis, N-(5'-phosphoribosyl)anthranilic acid (PRA) --> 1-(o-carboxyphenyl-amino)-1-deoxyribulose 5-phosphate (CdRP) --> indol-3-ylglycerol phosphate (InGP)+CO(2)+H(2)O, consists of a single polypeptide chain. The kinetic properties of the enzyme demonstrate that intermediate CdRP formed from PRA must dissociate from the enzyme before it can be converted into InGP. It is concluded that there are two distinct and non-overlapping catalytic sites on the enzyme for the two reactions. The expected complementation between a mutationally altered form of the enzyme lacking the first reaction and a mutationally altered form lacking the second reaction has been demonstrated in vitro by InGP formation from PRA. This system thus exhibits intracistronic complementation with a non-oligomeric protein gene product.