A high-copy-number plasmid capable of replication in thermophilic cyanobacteria

A 2.5 kb high-copy-number plasmid, pM A4 in thermophilic cyanobacterium Synechococcus sp. M A4 was isolated and characterized to develop a genetic engineering system for thermophilic cyanobacteria. The copy number of pM A4 was determined to be by densitometry about 350/cell. The pM A4 may be a type of rolling-circle plasmid, because a possible rep gene encoding 34 k D-protein and a consensus sequence of a double-stranded origin nick site of rolling circle plasmids were found in the pM A4 sequence. The pM A4 was electro-introduced into another thermophile, Synechococcus sp. MA 19, which is the strongest poly-β-hydroxybutyrate (PHB) accumulator in photoau totrophic organisms. The pM A4 was incorporated and retained in MA 19. These results indicate that pM A4 could be developed as a useful vector for thermophilic cyanobacteria.     

Rhodium-Catalyzed Addition of Organoboronic Acids to Aldehydes

Highly inert to ionic additions to aldehydes , aryl- and 1-alkenylboronic acids succumb to a catalytic variant mediated by a [Rh(acac)(CO)₂]–diphosphane complex in aqueous phase at 80–95°C to yield secondary alcohols [Eq. (a)]. A key step in the catalytic cycle is the transmetalation between the boron reagent and the rhodium complex. L_n=diphosphane (e.g. 1,1′-bis(diphenylphosphanyl)ferrocene); R=aryl, 1-alkenyl; R′=alkyl, aryl; acac=acetylacetonate.     

Preparation of hydrazinodeoxycellulose and carboxyalkyl hydrazinodeoxycelluloses and their adsorption behavior toward heavy metal ions

Nitrogen-containing cellulose derivatives hydrazinodeoxycellulose (HDC) and carboxyalkyl hydrazinodeoxycelluloses (α- and β-CAHDCs) were prepared from 6-chlorodeoxycellulose (CDC). Their adsorption of divalent transition metal ions was determined from dilute aqueous solutions and compared with that of aminoalkyl celluloses (AmACs) reported previously. HDC scarcely adsorbs metal ions in the pH range of 1–2, whereas α- and β-CAHDCs adsorb metal ions in this pH range. However, the adsorption of metal ions on HDC increases rapidly with increasing pH and HDC more effectively adsorbs metal ions than α- and β-CAHDCs in weakly acidic conditions. The ability to adsorb Cu²⁺ ions was in the order of AmAC (carbon number in the diamine moiety m = 2) > HDC > α-CAHDC > β-CAHDC in the weakly acidic region. These adsorbents selectively adsorb Cu²⁺ ions from the solutions containing other metal ions such as Mn²⁺, Co²⁺, and Ni²⁺, and the Irving–Williams series is obeyed in these adsorbent/metal ion systems. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3359–3363, 1997     

(Ethylenediaminetetraacetic Acid)cerium(IV) [CeIV(EDTA)] Complexes with Dual Hydrophobic Binding Sites as Highly Efficient Catalysts for the Hydrolysis of Phosphodiesters

β‐Cyclodextrin (β‐CD) derivatives 1 with an amino group at C(6), C(3), or C(2) were homogeneously linked together by an ethylenediaminetetraacetic acid (EDTA) bridge (Scheme). Coordination of the linker to metal ions and cooperation of the dual cavities of 3 in binding hydrophobic guests were properly demonstrated by NMR techniques and a fluorescence‐based titration method, respectively. The hydrolysis of bis(4‐nitrophenyl) phosphate (BNPP) in the presence of Ce^IV complexes of β‐CD dimers 3 was tens of millionfold faster than that in the absence of the Ce^IV complexes. Hydrophobic binding of the β‐CD cavities was estimated to contribute to the catalysis by a factor of up to 520, and the type of modified sugar unit and the bridging positions influenced this cooperation between the β‐CD moieties and the catalytic metal center.     

Cyclodextrin as a Macrocyclic Monomer: Cationic Ring‐Opening Polymerization of O‐Permethylcyclodextrins

It has been disclosed for the first time that a cyclodextrin (CD) derivative is able to act as a macrocyclic monomer for ring‐opening polymerization to produce linear polyglucan. O‐Permethylated α‐, β‐, and γ‐CDs were found to be polymerizable with the aid of a cationic initiator, e.g., Et₃O⁺PF₆^– in dichloromethane. Interestingly, the more strained monomer (α‐ > β‐ > γ‐CD) was less reactive, which is ascribable to the characteristic shape of the CD molecule.