A simple model is used to illustrate the relationship between the dynamics measured by NMR relaxation methods and the local residual entropy of proteins. The expected local dynamic behavior of well-packed extended amino acid side chains are described by employing a one-dimensional vibrator that encapsulates both the spatial and temporal character of the motion. This model is then related to entropy and to the generalized order parameter of the popular "model-free" treatment often used in the analysis of NMR relaxation data. Simulations indicate that order parameters observed for the methyl symmetry axes in, for example, human ubiquitin correspond to significant local entropies. These observations have obvious significance for the issue of the physical basis of protein structure, dynamics, and stability.

The malate carrier of barley (Hordeum vulgare L.) mesophyll vacuoles was highly purified by chromatography on hydroxyapatite followed by affinity-chromatography using 5-amino-1,2,3-benzenetricarboxylic acid as ligand. The carrier, reconstituted in asolectin liposomes, had properties similar to those described previously for the carrier in intact vacuoles (Martinoia, E., Flügge, U.I., Kaiser, G., Heber, U. and Heldt, H.W. (1985) Biochim. Biophys. Acta 806, 311-319). The apparent Km for malate uptake was 2-3 mM, and the uptake was inhibited by other carboxylic acids (preferentially tricarboxylic). The sulfhydryl reagent, p-chloromercuribenzenesulfonate, as well as the anion transport inhibitor 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid, also inhibited malate uptake. The transport was dependent on the membrane potential with an optimum at about 35 mV.

The tyrosine-3-monooxygenase activity [L-tyrosine, tetrahydropteridine: oxygen oxidoreductase (3-hydroxylating); EC 1.14.16.2] of rat adrenal medulla is induced 20-24 hr after the injection of reserpine (16 mumol/kg intraperitoneally). This and other inducing stimuli increase the 3': 5'-cyclic AMP (cAMP) content in the medulla for longer than 60 min and activate the cAMP-dependent protein kinase (ATP: protein phosphotransferase; EC 2.7.1.37) for several hours. Corticotropin (ACTH), dopamine, and propranolol do not induce the monooxygenase, but elicit an increase in the cAMP content of the medulla which fails to activate protein kinase and lasts less than 1 hr. A high- and low-molecular-weight protein kinase are separated by gel filtration from the 20,000 X g pellet extract of adrenal medulla homogenate. The activity of the low-molecular-weight enzyme is expressed as its ability to phosphorylate histone. The protein kinase activity of the pellet is increased between 3 and 17 hr after reserpine injection. Our evidence indicates that this increase is due to a translocation from cytosol to subcellular structures of a kinase that utilizes lysine-rich histone as phosphate acceptor. The protein kinase activity that is extracted from a purified nuclear fraction prepared from the adrenal medulla of rats injected 7 hr previously with reserpine is greater than that extracted from medulla of saline-treated rats.

Cytochrome P-450 from bovine adrenocortical mitochondria exists in three forms of molecular weight: 850,000 (protein 16), of one-half (protein 8), and of one-quarter of this value (protein 4). The forms of the enzyme are named according to the number of subunits and all appear to be active in converting cholesterol to 3beta-hydroxy-5-pregnen-20-one (side chain cleavage) (Shikita, M., and Hall, P.F. (1973) J. Biol. Chem. 248, 5606). To determine whether all three forms are active at their characteristic molecular weights, the three cytochromes were each layered onto separate sucrose density gradients and centrifuged at 49,000 rpm for 60 min; the gradients contained all the factors necessary for side chain cleavage including one of the following substrates: cholesterol, 20S-hydroxycholesterol, and 20S,22R-dihydroxycholesterol. Regardless of the form of P-450 layered onto the gradient and regardless of the substrate, enzyme activity (side chain cleavage) was observed only in fractions corresponding to a sedimentation coefficient of 20 to 22 S which is that for protein 16. No activity was observed at S values corresponding to either protein 8 or protein 4. These findings indicate that the active form of cytochrome P-450 from adrenocortical mitochondria is that containing 16 subunits, i.e. the form in which the cytochrome is normally isolated from adrenal mitochondria. Forms consisting of eight and four subunits which can be prepared from protein 16 become active only by forming protein 16, at least in an aqueous medium in vitro.

A patient with aortitis syndrome had a pleural effusion which subsided but reappeared with an exacerbation of aortitis symptoms while under antituberculosis treatment. The character of the fluid was that of an exudate, and the glucose concentration was normal. Clinical and laboratory features of the case suggest that the effusion was part of the aortitis syndrome per se.