Protein-polymer nano-machines. Towards synthetic control of biological processes

The exploitation of nature's machinery at length scales below the dimensions of a cell is an exciting challenge for biologists, chemists and physicists, while advances in our understanding of these biological motifs are now providing an opportunity to develop real single molecule devices for technological applications. Single molecule studies are already well advanced and biological molecular motors are being used to guide the design of nano-scale machines. However, controlling the specific functions of these devices in biological systems under changing conditions is difficult. In this review we describe the principles underlying the development of a molecular motor with numerous potential applications in nanotechnology and the use of specific synthetic polymers as prototypic molecular switches for control of the motor function. The molecular motor is a derivative of a TypeI Restriction-Modification (R-M) enzyme and the synthetic polymer is drawn from the class of materials that exhibit a temperature-dependent phase transition. The potential exploitation of single molecules as functional devices has been heralded as the dawn of new era in biotechnology and medicine. It is not surprising, therefore, that the efforts of numerous multidisciplinary teams [1,2]. have been focused in attempts to develop these systems. as machines capable of functioning at the low sub-micron and nanometre length-scales [3]. However, one of the obstacles for the practical application of single molecule devices is the lack of functional control methods in biological media, under changing conditions. In this review we describe the conceptual basis for a molecular motor (a derivative of a TypeI Restriction-Modification enzyme) with numerous potential applications in nanotechnology and the use of specific synthetic polymers as prototypic molecular switches for controlling the motor function [4]

A Tandem Sulfur Transfer/Reduction/Michael Addition Mediated by Benzyltriethylammonium Tetrathiomolybdate

Disulfides and sulfur containing organic compounds are important functional groups widely present in nature and have commercial significance.[1] Therefore, the synthesis of disulfides, sulfides, and w-thioketones is not only attractive but also finds numerous applications

A tandem sulfur transfer/reduction/michael addition mediated by benzyltriethylammonium tetrathiomolybdate

Disulfides and sulfur containing organic compounds are important functional groups widely present in nature and have commercial significance.[1] Therefore, the synthesis of disulfides, sulfides, and w-thioketones is not only attractive but also finds numerous applications

Physico-chemical and pharmacokinetic studies of avidin bioconjugates with thermosensitive polymers.

N-isopropilacrylamide-co-acrylamide 6000 Da with a LCST of 37\ub0C, was activated and conjugated to avidin. Gel permeation analysis demonstrated that the polymer conjugation modifies remarkably the protein hydrodynamic volume. The bioconjugate displayed higher LCST compared to the original polymer. The polymer conjugation altered slightly the protein tertiary structure and the binding with both biotin and bionylated antibodies. Pharmacokinetic studies demonstrated that the bioconjugate shows longer permanence in the blood stream as compared to the native protein

Catalytic Aerobic Oxidation of Cycloalkanes with Nanostructured Amorphous Metals and Alloys**

The functionalization of unactivated carbon-hydrogen bonds in saturated hydrocarbons has been investigated for both its synthetic and biological interest.[1] Catalytic oxidation of alkanes has been explored using several oxidants,[2] and those reactions with molecular oxygen under mild conditions[3] are especially rewarding goals. The oxidation of cyclohexane turns out to be the least efficient of all major industrial processes.[4

'Isothermal' phase transitions and supramolecular architecture changes in thermoresponsive polymers via acid-labile side-chains

Polymers designed to change their conformation via a phase transition triggered by acidic cleavage of a hydrophobic side-chain have been synthesized and characterised. The new materials were prepared by co-polymerising N-isopropylacrylamide with an acetal-containing pH-sensitive monomer N-(2-(2,4,6-trimethoxyphenyl)-1,3-dioxan-5-yl)acrylamide (TMPDA) and then grafting the resultant linear copolymers to branched poly(ethyleneimine). The final three-component polycations exhibited Lower Critical Solution Temperature (LCST) behaviour. The structures of these polymers, their solution behaviour and their self-association were characterized by DLS and TEM in water and buffer solutions. The acid-triggered hydrolysis of trimethoxybenzeneacetal side-chains on the poly(N-isopropylacrylamide-co-TMPDA) grafts resulted in changes in lower critical solution temperatures and in solution self-assembly; thus in effect creating an 'isothermal' phase transition. The changes in polymer conformation, at acidity levels corresponding to those in cell endosomes, offer promise for these polymers to act as controlled release materials