The Epstein-Barr virus.

Mixed-valence (MV) compounds are excellent model systems for the investigation of basic electron-transfer (ET) or charge-transfer (CT) phenomena. These issues are important in complex biophysical processes such as photosynthesis as well as in artificial electronic devices that are based on organic conjugated materials. Organic MV compounds are effective hole-transporting materials in organic light emitting diodes (OLEDs), solar cells, and photochromic windows. However, the importance of organic mixed-valence chemistry should not be seen in terms of the direct applicability of these species but the wealth of knowledge about ET phenomena that has been gained through their study. The great variety of organic redox centers and spacer moieties that may be combined in MV systems as well as the ongoing refinement of ET theories and methods of investigation prompted enormous interest in organic MV compounds in the last decades and show the huge potential of this class of compounds. The goal of this Review is to give an overview of the last decade in organic mixed valence chemistry and to elucidate its impact on modern functional materials chemistry.

Organic mixed-valence compounds: a playground for electrons and holes.

A novel enzyme responsible for the oxidation of spermidine and spermine has been found in rat liver. Spermidine is shown to be degraded to putrescine and 3-aminopropionaldehyde, and spermine to be cleaved to spermidine and 3-aminopropionaldehyde. A single enzyme catalyzing both reactions and designated as polyamine oxidase has been purified 4000-fold to electrophoretic homogeneity. Polyamine oxidase appears to be a flavoprotein, containing flavin adenine dinucleotide (FAD) as a prosthetic group. Hydrogen peroxide is evolved in the reaction and no other electron acceptors except molecular oxygen have been found. The molecular weight of the enzyme was approximately 60 000 and the sedimentation coefficient 4.5 S. The enzyme appears to be a single polypeptide chain since no evidence for structural subunits was obtained. Polyamine oxidase was sensitive to sulfhydryl and carbonyl group reagents. The optimum pH value for the oxidation of polyamines was close to 10. The reaction velocities were enhanced by various aldehydes, especially certain aromatic aldehydes. Polyamine oxidase appears to be localized in peroxisomes of liver cells, although the existence of an isoenzyme in the cytosolic fraction was not definitively ruled out. No marked changes were observed in the activity of polyamine oxidase in rat liver after partial hepatectomy, carbon tetrachloride poisoning, and after treatment with growth hormone or thioacetamide, conditions which are known to alter profoundly the metabolism and accumulation of polyamines.

Oxidation of spermidine and spermine in rat liver: purification and properties of polyamine oxidase.

Cyclopropane amino acids: 2,3- and 3,4-Methanoamino acids

Synthesis of Methylene- and Alkylidenecyclopropane Derivatives.

THE following is the initial report of a structurally unique monoamine oxidase inhibitor, N-benzyl-N-methyl-2-propynylamine hydrochloride (A19120). This work includes in vitro action of this inhibitor on rat liver mitochondria as well as in vivo inhibition of monoamine oxidase of mouse brain and the liver.

New inhibitor of monoamine oxidase.

SHEEP pulmonary adenomatosis (SPA) or Jaagsiekte is a contagious disease of unknown aetiology1. A herpesvirus has been isolated from such tumours in Britain2 and in Africa3,4 but attempts to produce adenomata with this virus have been unsuccessful (ref. 5 and W.B.M., G. Robinson, and K.W.A., in preparation). More recently, evidence has been presented that a type C virus with a density on a sucrose gradient of 1.5–1.20 g ml−1, containing 60–70S RNA and RNA-directed DNA polymerase (reverse transcriptase) is present in the adenomatous tissue6. We wish to describe the production of SPA tumours in sheep experimentally infected with both agents.

Experimental production of sheep pulmonary adenomatosis (Jaagsiekte).

Electron spin resonance studies of the radical anions of [2.2]paracyclophane and related compounds

Benzaldehyde is condensed with methylamine to give a Schiff base, which, in turn, is hydrogenated with palladium on charcoal to give benzylmethylamine. This is alkylated with propargyl bromide to yield pargyline. We were quite fortunate that soon after we inaugurated our search for a nonhydrazine M A 0 inhibitor, Taylor and Wykes devised a rapid in uitro screening method. This method was reported at the Federation Proceedings in March, 1959.' It is based upon the production of a dark brown pigment through the action of the M A 0 enzyme on the substrate serotonin. Graded levels of inhibitors roduced corresponding graded responses in

Structure-activity relations in the pargyline series.

Regression analysis of the potency of inhibition of monoamine oxidase by 47 propynylamines revealed that there are three determinants of inhibitory potency: (1) the smallest substituent on the nitrogen must be methyl or hydrogen in order for any activity to be observed; (2) potency is parabolically related to pKa-the optimum pKa is 6.2; and (3) ortho-substituted benzylamine analogs are ten times more potent than predicted on the basis of pKa values. The optimum pKa cannot be explained by differences in fraction ionized but rather in terms of the multistep sequence whereby these compounds inhibit MAO. A very slight positive effect of hydrophobicity on potency was found. The potency of several analogs not included in the original analysis was predicted.

William B. Martin

Papers

New inhibitor of monoamine oxidase.

Experimental production of sheep pulmonary adenomatosis (Jaagsiekte).

Electron spin resonance studies of the radical anions of [2.2]paracyclophane and related compounds

Structure-activity relations in the pargyline series.

Regression analysis of the relation between physical properties and the in vitro inhibition of monoamine oxidase by propynylamines