Theoretical analysis of a site-specific chemiluminescence reaction and its application to quantitation of lipid hydroperoxides

A system was designed for chemiluminescent measurement of lipid hydroperoxides by their site-specific reaction in sodium dodecylsulfate micelles. Ferrous ion-induced decomposition of lipid hydroperoxides in the sodium dodecylsulfate micelles resulted in strong chemiluminescence of the Cypridina luciferin analog, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-alpha]pyrazin-3-one (CLA). After addition of ferrous sulfate to the micelles containing lipid hydroperoxide and luciferin, the chemiluminescence intensity reached a maximum rapidly and then decreased. The sequence of this reaction was elucidated by theoretical analysis, which demonstrated that the maximum chemiluminescence intensity is proportional to the initial concentration of hydroperoxide. Good linear relationships were observed between the maximum counts of chemiluminescence and the amounts of hydroperoxides of linoleic acid, phosphatidylcholine, choresterol (5 alpha), cumene and tert-butyl and hydrogen peroxide. This chemiluminescence method was simple and sensitive enough to detect picomole levels of linoleic acid and phosphatidylcholine hydroperoxides.     

Characterization of a Mr = 56,000 polypeptide associated with 10S DNA polymerase alpha purified from calf thymus using monoclonal antibody.

Existence of a Mr = 56,000 polypeptide associated with 10S DNA polymerase alpha was shown by production of a monoclonal anti-calf thymus 10S DNA polymerase alpha antibody secreted from a hybridoma line named 3H1. The antibody bound three polypeptides with Mr = 180,000, 56,000 and 32,000 in hydroxylapatite fraction of 10S DNA polymerase alpha by immunoblot. The antibody co-precipitated the polypeptides with the large polypeptide (Mr = 150,000-140,000) of 10S DNA polymerase alpha with the aid of second antibody. Among three polypeptides, the Mr = 56,000 polypeptide was co-purified with DNA polymerase alpha through DNA-cellulose chromatography and repeated sucrose rate-zonal centrifugations. The Mr = 56,000 polypeptide was still associated with 10S DNA polymerase alpha after second sucrose rate-zonal centrifugation, but the amount of it was reduced. The polypeptide was banded at pH 7.2-8.0 and displayed microheterogeneity in respect of isoelectric point by isoelectrofocusing with 7 M urea, and showed weak DNA-binding property after blotting onto a nitrocellulose. The antibody against the polypeptide precipitated DNA polymerase alpha from human, rat, and mouse, and Mr = 56,000 and 32,000 polypeptides were detected in these DNA polymerase alpha fractions by immunoblot. These results suggest that the polypeptide with Mr = 56,000 may take part in the DNA polymerase reaction.     

Physicochemical and immunochemical properties of a thermo-labile antigen (TLA a) from yeast cell surface

The physicochemical and immunochemical properties of a thermo-labile antigen (TLA a) which is located on the cell surface of Saccharomyces cerevisiae were studied. The sedimentation constant (S20,W) and molecular weight (sedimentation equilibrium method) were 6.26S and 68,800, respectively. The circular dichroic (CD) spectrum of TLA a had negative maxima at 210 and 221 nm, indicating the presence of alpha-structure of a polypeptide chain. The molar ratio of antibody to antigen which gave maximum precipitation was 2.7. Approximately 50% of the antigenic activity of heat-denatured TLA a was recovered when denatured molecules were dissolved in 6 M guanidine hydrochloride followed by 25-fold dilution with H2O. The amount of TLA a existing on the yeast cell surface was estimated to be 37.5 micrograms per 10.5 mg of fresh cells, corresponding to 0.36% by weight of the fresh yeast.     

Sodium and Chloride Ion-Dependent Transport of β-Alanine Across the Blood-Brain Barrier

Abstract: The characteristics of β-alanine transport at the blood-brain barrier were studied by using primary cultured bovine brain capillary endothelial cells. Kinetic analysis of the β-[³H]alanine transport indicated that the transporter for β-alanine functions with K_t of 25.3 ± 2.5 µ M and J _max of 6.90 ± 0.48 nmol/30 min/mg of protein in the brain capillary endothelial cells. β-[³H]Alanine uptake is mediated by an active transporter, because metabolic inhibitors (2,4-dinitrophenol and NaN₃) and low temperature reduced the uptake significantly. Furthermore, the uptake of β-[³H]alanine required Na⁺ and Cl⁻ in the external medium. Stoichiometric analysis of the transport demonstrated that two sodium ions and one chloride ion are associated with one β-alanine molecule. The Na⁺ and Cl⁻-dependent uptake of β-[³H]alanine was stimulated by a valinomycin-induced inside-negative K⁺-diffusion potential. β-Amino acids (β-alanine, taurine, and hypotaurine) inhibited strongly the uptake of β-[³H]alanine, whereas α- and γ-amino acids had little or no inhibitory effect. In ATP-depleted cells, the uptake of β-[³H]alanine was stimulated by preloading of β-alanine or taurine but not l -leucine. These results show that β-alanine is taken up by brain capillary endothelial cells, via the secondary active transport mechanism that is common to β-amino acids.     

Metamorphic Changes in Glycolipids and Myelin Proteins and 2',3'-Cyclic Nucleotide 3'-Phosphohydrolase in Bullfrog and Axolotl Brains

Abstract: The metamorphic changes in levels of glycolipids and myelin proteins and 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) in the brains of bullfrog tadpoles, adult frogs, and axolotls were investigated, with particular emphasis on myelin maturation. The concentrations of cerebroside. sulfatide, and galactosyldiacylglycerol gradually increased from the onset of prometamorphosis throughout the active metamorphic period and then greatly increased after metamorphosis was completed. The ratio of glucocerebroside to galactocerebroside increased greatly in the prometamorphic period and then rapidly decreased to the frog level during the climax period. The fatty acid compositions of cerebroside and sulfatide showed a developmental change, with 24:1 being more predominant in the later metamorphic stage. The proportion of hydroxy fatty acids increased up to the onset of the prometamorphic stage and thereafter remained constant at ∼ 50% of the total. The CNP activity remained unchanged throughout metamorphosis at 60% that in frog myelin and increased in the adult frog. The composition of tadpole myelin proteins remained constant during metamorphosis, with large basic protein being the most abundant, and in the frog, proteolipid protein and large basic protein were present in comparable amounts. The two adult forms of axolotl, i.e., the neotenous and metamorphosed forms, exhibited almost identical myelin constituents, and CNP activity in the neotenous form amounted to one-fifth that in the bullfrog. These results indicate that active biosynthesis of myelin marker components occurs as metamorphosis proceeds, but more pronounced changes of myelin components occur after metamorphosis is completed.