Conversion of DOPA to tetrahydroisoquinolines and stizolobic acid in a callus culture of Stizolobium hassjoo

Isolation and identification of l-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline and l-1-methyl-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline from seeds and callus of S. hassjoo are described. Administration of [β-¹⁴C]-labelled DOPA to a callus culture of this legume resulted in the incorporation of radioactivity into l-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, l-1-methyl-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline and stizolobic acid, which was confirmed by constant specific radioactivity after co-crystallization with authentic samples of each compound.     

Absorption of Copper by Lemna as Influenced by Some Factors Which Nullify the Copper Effect on Flowering and Growth

The effect of copper on flowering and growth of Lemna paucicostata6746 and Lemna gibba G3 in a copper-containing medium is nullifiedby the addition of EDTA, ammonium ions or salicylic acid tothe medium or a decrease in its nitrate concentration. Thesefactors were examined for their effects on the absorption ofcopper by the plants. The addition of EDTA to the medium completelyinhibited the absorption of copper in both species, thus eliminatingthe copper effect. Ammonium ions also inhibited copper absorption,their effectiveness rising with their concentration. Loweringthe nitrate concentration in the medium nullified the coppereffect on flowering in L. paucicostata 6746, and the additionof salicylic acid to the medium also nullified the copper effectin L. gibba G3, both without affecting the absorption of copper. (Received June 7, 1982; Accepted August 27, 1982)     

Simple procedures for the rapid cleavage of ester lipids and for the large-scale isolation from brain of cerebroside sulfate

The ester groups of glycerophospholipids in tissue extracts can be cleaved in less than 10 min at room temperature if the lipids are extracted with hexane-isopropanol and the filtrate is treated with methanolic NaOH. The resulting mixture can be treated with aqueous Na-sulfate containing sulfuric acid and partitioned to remove the inorganic reagents and hydrophilic ester degradation products. When the procedure is applied to brain lipid extracts, the addition of alkali produces a second, lower phase that contains much of the hydroxycerebroside, virtually all of the sulfatide in the extract, and small amounts of other lipids. The sulfatide can be isolated from the lower phase by neutralizing it with HCl in aqueous methanol, and partitioning with chloroform to remove nonlipid components. The lower phase is evaporated to dryness and treated with periodic acid to convert the cerebroside to a less polar product. The lipids recovered from the reaction mixture are then fractionated with a Florisil column, which yields highly purified sulfatide. Starting with 300 g of pig brain one can obtain about 1.1 g of sulfatide in 4 working days, using conventional, compact equipment. Since the precipitation step is almost complete, and the procedure can be scaled down to very low levels, the method has promise for quantitation methods and isotopic studies of sulfatide metabolism.     

The terminal oxidase of Photobacterium phosphoreum. A novel cytochrome

The terminal oxidase of Photobacterium phosphoreum has been purified to the electrophoretically homogeneous state and some of its properties have been studied.The enzyme catalyses oxidation of ascorbate in the presence of phenazine methosulphate or N,N,N′,N′-tetramethyl-p-phenylenediamine. The reaction is inhibited by cyanide. Nitrite at comparatively high concentrations inhibits the enzyme, but the enzyme does not catalyse nitrite reduction with ascorbate plus the electron mediator as the electron donor.The enzyme shows the absorption peaks at 632, 565, 534 and 436 nm in the reduced form. It has two kinds of haems: protohaem and haem d. Namely, the enzyme is a ‘cytochrome bd’-type oxidase; a novel cytochrome.     

Coenzyme B12-dependent diol dehydrase: Chemical modification with 2,3-butanedione and phenylglyoxal

The apoenzyme of diol dehydrase was inactivated by two arginine-specific reagents, 2,3-butanedione and phenylglyoxal, in borate buffer. In both cases, the inactivation followed pseudo-first-order kinetics. Kinetic data show that the incorporation of a single reagent molecule per active site of the enzyme is necessary for the complete inactivation. The modification with 2,3-butanedione was reversed by dilution of the reagent and borate concentrations (65% activity recovered). 1,2-Propanediol (substrate) partially protected the enzyme against inactivation. The holoenzyme was almost insensitive to 2,3-butanedione and phenylglyoxal, indicating that the essential arginine residue is prevented from the attack of these reagents either by direct blockage with the bound coenzyme or by an indirect conformational change caused by coenzyme binding. The inactivation of diol dehydrase by 2,3-butanedione did not result in dissociation of the enzyme into subunits. From these results, we concluded that the essential arginine residue is located at or in close proximity to the active site of diol dehydrase.     

Stereoselective hydrolysis of dl-menthyl succinate by gel-entrapped Rhodotorula minuta var. texensis cells in organic solvent

Summary dl-Menthyl succinate was successfully hydrolyzed stereoselectively by Rhodotorula minuta var. texensis cells entrapped within photo-crosslinked or polyurethane resin gels in water-saturated n-heptane. The hydrolyzed product was found to be pure l-menthol. The catalytic activity of the immobilized cells, especially those entrapped in urethane polymers, was far more stable than that of the free cells. The half-life of the polyurethaneentrapped cells was estimated to be 55–63 days in the organic solvent.Dedicated to the 65th birthday od Professor Dr. G. Manecke     

Polynucleotides. L. Synthesis and properties of poly (2''-chloro-2''-deoxyadenylic acid) and poly (2''-bromo-2''-deoxyadenylic acid).

Poly (2'-chloro-2'-deoxyadenylic acid) and poly (2'-bromo-2'-deoxyadenylic acid) were synthesized from the corresponding diphosphates with the aid of polynucleotide phosphorylase from E. coli. UV, CD, acid titration and mixing with poly (U) were investigated. Comparing these properties with those of poly (A) and poly (2'-azido-2'-deoxyadenylic acid), it was found that 2'substituents exert significant effects on the thermal stability of these polynucleotides, though the overall conformational structure was not greatly changed.     

Phosphoglucomutase from potato tubers. Chemical and catalytic properties.

The chemical and catalytic properties of potato phosphoglucomutase [EC 2.7.5.1] were studied using various enzyme species (Peaks Ia, Ib, Ic, and II; Takamiya, S. & Fukui, T. (1978) Plant Cell Physiol. 19, 319--328). The molecular weights of the species are all approximately 60,000. No indication of the presence of subunit structure was obtained under various conditions. The amino acid composition of Peak Ia is generally similar to those of the enzymes from other sources, though it has some peculiarities. The Peak Ia and Peak II enzymes both absolutely require alpha-D-glucose 1,6-bisphosphate and Mg2+ for activity, and appear to have a "ping-pong" mechanism. A low concentration of Be2+ inhibits their action, the inhibition being retarded either by Mg2 or EDTA. Although the inhibition patterns by various metabolites, are similar for Peaks Ia and II, they differ in their kinetic parameters and optimal pH values.