Macromolecular acids, catalysis

The present chapter tries to set out some of the problems of catalysis by insoluble macromolecular acids and to establish its relationship to proton transfer processes in general. Of necessity... 

The procedure cannot immediately be transferred to the study of catalysis by solid macromolecular acids since the hydrogen ion concentration in the resin phase is not so easily regulated. Because of the Donnan equilibrium between internal and external phases, the internal and external hydrogen ion concentrations can differ by several powers of ten [48], and there is no straightforward method of relating buffer ratio and external or internal pH. 

We next measure k for a reaction thought to be capable of being catalysed by the macromolecular acid, in the presence of the same resin and at the same value of a. If it is assumed that also for this reaction the same rate constant applies for hydrogen ion catalysis inside the resin and in homogeneous solution, it is then possible to evaluate ha equation 14. 

Experimental conditions can be realized for which diffusion effects are not important and for which the two-phase model of catalysis by insoluble macromolecular acids represents a fair first-order theory. 

Evidence continues to support the explanation of en/.yme catalysis on the basis of the active site (reactive center) of amino acid residues, which is considered to be that relatively small region of the en/yme s macromolecular surface involved in catalysis. Within this site, the enzyme has. strategically positioned functional groups (frnm the side chains of amino acid units) that participate cooperatively in the catalytic action." ... 

Macromolecular crystallography is a very powerful method used to study complex biological systems. The structures of a wide variety of proteins, nucleic acids and their assemblies have been determined at atomic or near-atomic resolution. As a result, a detailed understanding has been gained of various living processes such as enzyme catalysis, the immune response, the encoding of hereditary information, viral infection and photosynthesis. 

Amino-acids, Peptides, and Proteins Carbohydrate Chemistry Catalysis Colloid Science Electrochemistry Electron Spin Resonance Environmental Chemistry General and Synthetic Methods Heterocyclic Chemistry Macromolecular Chemistry Mass Spectrometry Nuclear Magnetic Resonance Organometallic Chemistry Organophosphorus Chemistry Photochemistry... 

Catalysts played an important role in the emergence of life on Earth nearly 4 billion years ago. Catalysis by mineral surfaces and small molecules enabled the emergence of a proto-metabolic network that, in turn, enabled the emergence of the RNA world. The first macromolecular catalysts may have been ribozymes, an idea first proposed by Carl Woese that gained credence with the discovery of catalytic RNAs by Cech and Altman. Subsequently, ribozymes generated by in vitro evolution methods have been shown to catalyze a wide range of reactions involved in metabolism, including amino acid activation formation of coenzyme A (CoA), nicotinamide adenine dinucleotide (NAD), and flavin adenine dinucleotide (FAD)... 

The first chapter of the book deals with enzyme-like eatalysis by synthetic polymers - catalysis by polymeric acids and bases, amphoteric polyelectrolytes and nonionic polymers. Because coordination compounds of metal ions with macromolecular ligands are interesting with regard to bioinorganic chemistry, this book elucidates some problems involving the catalysis by water-soluble polymer-metal complexes. Ester hydrolysis, hydrogen peroxide decomposition, oxidation of disubstituted phenols, hydroquinones, mercaptoalcohols and other types of reaction are chosen as model processes. A section devoted to interfacial catalysis is also included. 

The interaction of artificial metal ions/complexes with peptides/proteins [11], nucleic acids/DNA [12,13], enzymes [14], steroids [15] and carbohydrates [16] forms a bridge between natural and artificial macromolecular metal complexes. Biometal-organie chemistry concentrates on such complexes [17]. The reason for the increasing interest in this field lies in medical applications of metal complexes (cancer, photodynamic therapy of cancer, immunoassays, fluorescence markers, enantioselective catalysis, template orientated synthesis of peptides, etc.). Figure 2-4 presents an overview of metals in medicine [18]. Some examples are given below. 

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