Enzymatic determination of zinc in vegetables using apocarbonic anhydrase

A new enzymatic method has been developed to determine trace amounts of Zn2+ in vegetables. The basis of the method is that apocarbonic anhydrase regains its activity in proportion to the concentration of Zn2+ present in solution. Bovine carbonic anhydrase was purified from erythrocyte haemolysate by affinity chromatography and the bound Zn2+ removed by dialysis of purified enzyme against a solution of pyridine-2, 6-dicarboxylic acid. Pure (100%) apoenzyme was obtained. The concentration of Zn2+ in vegetable samples was determined using the enzymatic method and by atomic absorption spectroscopy. Determinations made using the two methods were not significantly different one from another.     

The interaction of cobalt (II) complexes with bovine apocarbonic anhydrase B.

The second-order rate constants for interaction of a number of cobalt(II) complexes (including the aquated ion) with bovine apocarbonic anhydrase have been measured at pH equal to 7.5, 25 degrees C and I equal 0.1 M. The ease of entry of cobalt decreases, in general, as the number of its coordinated watersdecreases. The highest complexes (bis or tris) do not react. The Mono cobalt(II) -8-quinolinol-5-sulfonate and, particularly, 8-quinolinol complexes react very much more rapidly with apoenzyme than does Co(H20)6-2+ ion. The results are discussed.     

A simple and convenient preparation of succinic semialdehyde

Succinic semialdehyde (SSA) is prepared from 4-pentenoic acid by ozonolysis and reductive decomposition of the formed ozonide (40–50% yields). Aqueous solutions of SSA are obtained by water extraction from ethyl acetate solution of the mixture of reaction. Quantitative estimation of SSA was performed enzymatically by means of SSA dehydrogenase.     

A rapid and convenient preparation of [4-3H]NADP and stereospecifically tritiated NADP3H

The glass-binding properties of a number of purified glycoproteins capable of promoting attachment and spreading of a variety of types of animal cells in culture have been examined. Two such factors in human serum, fibronectin and serum spreading factor, exhibited strong affinities for glass beads and could be eluted from glass-bead columns under similar conditions. A number of other glycoproteins of human serum that do not promote cell adhesion did not bind to glass beads under conditions that resulted in binding of serum spreading factor or fibronectin. At a sufficiently low ratio of serum volume to glass-bead volume, human serum could be simultaneously depleted of serum spreading factor, fibronectin, and cell spreading-promoting activity by glass-bead affinity chromatography. Laminin, another cell spreading-promoting glycoprotein, possessed glass-binding properties similar to those of serum spreading factor and fibronectin while chondronectin, a fourth cell spreading-promoting factor of more limited specificity of biological activity and distribution in vivo, did not exhibit a strong interaction with glass beads under the same conditions. These observations suggest that glass-bead column affinity chromatography may prove useful as a general method for isolation and study of glycoprotein factors promoting attachment and spreading of cells in culture.     

A convenient and rapid method for genetic transformation of E. coli with plasmids

A convenient and rapid method for the genetic transformation of Escherichia coli with plasmids is proposed. By mixing the recipient cells and plasmid DNA and spreading them directly on selective medium plates containing Ca2+, the so-called 'plate transformation' could achieve almost the same transformation efficiency as the classical transformation method with calcium. The whole protocol takes only about 2 min, its simplicity compared favorably, not only to the usual protocol, but also to all other documented modifications.     

A rapid and convenient synthesis of poly-thymidylic acid by the modified triester approach.

By using anhydrous triethylamine-pyridine to selectively remove the cyanoethyl group from the fully protected oligonucleotide, a substantial improvement has been achieved in yields and the rates of condensation by the modified triester approach from the 5' leads to 3' end. The unreacted oligonucleotide containing the 5'-hydroxy group was removed by treatment with bis (triazolyl)-p-chlorophenyl phosphate after each condensation in situ. These modifications, as exemplified by the synthesis of fully protected T12, T18, T24 and T38 in 80%, 77%, 70% and 50% yields respectively, should allow the ready synthesis of polynucleotides of even longer chain lengths by purely chemical methods.     

A new, convenient method for the rapid analysis of inorganic pyrophosphate.

A new method for the rapid analysis of inorganic pyrophosphate (PP_i) which utilizes the enzyme ATP sulfurylase is described. All components of the assay system are commercially available and inexpensive. The assay is linear over the range of 0.5–50.0 nmol of PP_i and is not affected by inorganic phosphate. ATP and PP_i can both be analyzed using this method.     

A rapid and convenient method for purification and isolation of chlorophyll-A from Porphyra yezoensis.

A rapid and convenient method for purification and isolation of chlorophyll-a from Porphyra yezoensis without any chromatographic procedures has been developed. Thin-layer chromatographic and high-performance liquid chromatographic tests revealed that chlorophyll-a preparations in this study did not contain any other photosynthetic pigments and their degradation products.     

A rapid method for preparation of calf spleen exonuclease.

Chromatography on Concanavalin A sepharose is a simple procedure for partial purification of spleen phosphodiesterase. This procedure removes much, but not all, of the ribonuclease activity found as contaminant in most spleen phosphdisterase preparations.     

Stereospecificity of phenylpyruvate tautomerase. A convenient method for the preparation of chirally labelled phenylpyruvates.

1. By 1H nuclear magnetic resonance spectroscopy it has been shown that phenylpyruvate tautomerase from beef kidney catalyses the stereospecific exchange of one of the enantiotopic 3H-atoms in the side-chain of the substrate with solvent protons, the rate of spontaneous exchange being slow under physiological conditions. 2. Using monodeuterated phenylpyruvate of known absolute configuration it has been shown that the tautomerase removes specifically the 3-pro-R hydrogen atom of the substrate. 3. The circular dichroism spectra of the two enantiomeric 3-phenyl-[3-2H]pyruvates have been determined. 4. Some implications of these findings for the investigation of the metabolism of aromatic amino acids are discussed.