Resolution of cyclic AMP stimulated protein kinase from polymerization-purified brain microtubules.

Polymerization-deploymerization purified microtubules from mouse brain contain, in addition to tubulin, several minor proteins, including protein kinase activity. The protein kinase copurifies with microtubules in constant proportion to tubulin through two, three, or four cycles of polymerization; it can be resolved from tubulin by gel filtration chromatography and has an apparent molecular weight of 280,000. Its activity is stimulated 7-fold by cyclic AMP, and resembles the soluble brain protein kinase described by Miyamoto $\text{et al.}$ (1). The microtubule preparation serves as an endogenous substrate for this protein kinase; both 6S and 30S tubulin are substrates for phosphorylation to the extent of about 0.10 ± 0.05 moles/mole.     

Endo-beta-galactosidase of Escherichia freundii. Hydrolysis of pig colonic mucin and milk oligosaccharides by endoglycosidic action.

The purified keratansulfate degrading enzyme from $\text{Eschericia freundii}$ could hydrolyze desialyzed pig colonic mucin and milk oligosaccharides. Desialyzed pig colonic mucin was digested to produce GlcNAcβ(1→3)Gal, GlcNAc-6Sβ(1→3)Gal and resistant polymer. Lacto-N-tetraose and lacto-N-tetraitol were hydrolyzed endoglycosidically to release glucose and sorbitol, respectively. Therefore, this enzyme was found to be an endo-β-galactosidase of rather wide specificity.     

Adrenal medullary cyclic nucleotide phosphodiesterase: lack of activation by the calcium-dependent regulator.

Calcium-dependent regulator, a calcium-binding protein isolated from brain and adrenal medulla, has been shown to activate a brain calcium-sensitive cyclic nucleotide phosphodiesterase. To determine if this protein has the same role in the adrenal medulla, the cyclic nucleotide phosphodiesterase of adrenal medulla was characterized. Neither crude nor partially purified adrenal medullary phosphodiesterase was inhibited by EGTA or stimulated by calcium and the calcium-dependent regulator, whereas similar brain preparations displayed sensitivity to these agents. As the calcium-dependent regulator does not appear to stimulate adrenal medullary cyclic nucleotide phosphodiesterase activity, alternate roles of this protein in adrenal medulla are suggested.     

Isothiocyanates. A new class of uncouplers

This paper describes the uncoupling effect of three isothiocyanates: p-bromophenylisothiocyanate, 4,4′-diisothiocyanatebiphenyl and β-naphtylmethylisothiocyanate on the respiration of Ehrlich-Lettré cells and isolated mitochondria. The isothiocyanates are similar to other uncouplers (such as 2,4-dinitrophenol and carbonyl cyanide p-trifluoromethoxyphenylhydrazone) in that they: 1. stimulate respiration of state 4 mitochondria; 2. stimulate mitochondrial ATPase activity; 3. release the inhibition of mitochondrial respiration by oligomycin and 4. inhibit both mitochondrial respiration and mitochondrial ATPase activity at higher molar concentrations. The uncoupling activity of these isothiocyanates correlates well with their biological activity. Maximal activation of a latent mitochondrial ATPase activity of rat liver mitochondria in the presence of p-bromophenylisothiocyanate was found at a concentration of 15 μM. The investigated isothiocyanates differ significantly in their solubility in organic solvents and their chemical reactivity. We assume that the greater the partition coefficient in a series of isothiocyanates grouped according to the increasing value of log P (partition coefficient for the system octanol/water, 25 °C), the greater will be their uncoupling activity, but only up to a certain degree. Any further increase of log P will be marked by a decrease of this activity.     

β-Diketones in Rhododendron waxes

Chromatographic, mass spectrometric and spectroscopic evidence has been obtained for four β-diketones occurring in the leaf waxes of some members of     

Incorporation of methionine-[methyl-2H3] and mevalonic acid-[2-14C,(4R)-4-3H1] into Phycomyces blakesleeanus sterols

Ergosterol, episterol, 4α-methyl-5α-ergosta-8,24(28)-dien-3β-ol and 24-methylene-24,25-dihydrolanosterol, isolated from Phycomyces blakesleeanus grown in the presence of methionine-[methyl-²H₃], each contained two deuterium atoms; lanosterol, however, was unlabelled. The ¹⁴C:³H atomic ratio of the following sterols isolated from P. blakesleeanus grown in the presence of mevalonic acid-[2-¹⁴C,(4R)-4-³H₁], was: ergosterol, 5:3; episterol, 5:4; ergosta-5,7,24(28)-trien-3β-ol, 5:3; 4α-methyl-5α-ergosta-8,24(28)-dien-3β-ol, 5:4; 24-methylene-24,25-dihydrolanosterol, 6:5; lanosterol, 6:5. The significance of these results in terms of ergosterol biosynthesis is discussed.