http://basicmed.med.ncku.edu.tw/admin/up_img/990319-2.pdf

Matrix Crosslinking Forces Tumor Progression by Enhancing Integrin Signaling

Collagen is the most abundant protein in animals. This fibrous, structural protein comprises a right-handed bundle of three parallel, left-handed polyproline II-type helices. Much progress has been made in elucidating the structure of collagen triple helices and the physicochemical basis for their stability. New evidence demonstrates that stereoelectronic effects and preorganization play a key role in that stability. The fibrillar structure of type I collagen—the prototypical collagen fibril—has been revealed in detail. Artificial collagen fibrils that display some properties of natural collagen fibrils are now accessible using chemical synthesis and self-assembly. A rapidly emerging understanding of the mechanical and structural properties of native collagen fibrils will guide further development of artificial collagenous materials for biomedicine and nanotechnology.

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Collagen Structure and Stability

Nature’s hierarchical materials

/pdf/recent-advances-in-the-biochemistry-of-polyamines-in-382j7cp9ea.pdf

Recent advances in the biochemistry of polyamines in eukaryotes.

Starting from the early 1990’s, the chemistry of polyvalent iodine organic compounds has experienced an explosive development. This surging interest in iodine compounds is mainly due to the very useful oxidizing properties of polyvalent organic iodine reagents, combined with their benign environmental character and commercial availability. Iodine(III) and iodine(V) derivatives are now routinely used in organic synthesis as reagents for various selective oxidative transformations of complex organic molecules. Several areas of hypervalent organoiodine chemistry have recently attracted especially active interest and research activity. These areas, in particular, include the synthetic applications of 2-iodoxybenzoic acid (IBX) and similar oxidizing reagents based on the iodine(V) derivatives, the development and synthetic use of polymer-supported and recyclable polyvalent iodine reagents, the catalytic applications of organoiodine compounds, and structural studies of complexes and supramolecular assemblies of polyvalent iodine compounds.

The chemistry of polyvalent iodine has previously been covered in four books1–4 and several comprehensive review papers.5–17 Numerous reviews on specific classes of polyvalent iodine compounds and their synthetic applications have recently been published.18–61 Most notable are the specialized reviews on [hydroxy(tosyloxy)iodo]benzene,41 the chemistry and synthetic applications of iodonium salts,29,36,38,42,43,46,47,54,55 the chemistry of iodonium ylides,56–58 the chemistry of iminoiodanes,28 hypervalent iodine fluorides,27 electrophilic perfluoroalkylations,44 perfluoroorgano hypervalent iodine compounds,61 the chemistry of benziodoxoles,24,45 polymer-supported hypervalent iodine reagents,30 hypervalent iodine-mediated ring contraction reactions,21 application of hypervalent iodine in the synthesis of heterocycles,25,40 application of hypervalent iodine in the oxidation of phenolic compounds,32,34,50–53,60 oxidation of carbonyl compounds with organohypervalent iodine reagents,37 application of hypervalent iodine in (hetero)biaryl coupling reactions,31 phosphorolytic reactivity of o-iodosylcarboxylates,33 coordination of hypervalent iodine,19 transition metal catalyzed reactions of hypervalent iodine compounds,18 radical reactions of hypervalent iodine,35,39 stereoselective reactions of hypervalent iodine electrophiles,48 catalytic applications of organoiodine compounds,20,49 and synthetic applications of pentavalent iodine reagents.22,23,26,59

The main purpose of the present review is to summarize the data that appeared in the literature following publication of our previous reviews in 1996 and 2002. In addition, a brief introductory discussion of the most important earlier works is provided in each section. The review is organized according to the classes of organic polyvalent iodine compounds with emphasis on their synthetic application. Literature coverage is through July 2008.

Chemistry of Polyvalent Iodine

PERSPECTIVES AND SUMMARy 717 LYSYL OXIDASE 719 COLLAGEN 720 Allysine and Hydroxyallysine Pathways 720 Hydroxypyridinium Residues... ... 724 Molecular Sites 730 Basement Membranes 733 Methods oj Analysis 734 Alternative M echanisms ..... ... 734

Cross-linking in collagen and elastin

Specific detection of quinoproteins by redox-cycling staining.

$alpha$-AMINO ALCOHOLS AS PRODUCTS OF A REDUCTIVE SIDE REACTION OF DENATURED COLLAGEN WITH SODIUM BOROHYDRIDE.

Collagen is produced by WI-38 diploid human fibroblast cultures throughout their life cycle. It is examined by a sensitive method based on the analysis of specific peptides obtained after digestion with bacterial collagenase. The production and hydroxylation of the collagen is strongly dependent upon the age (population doublings) of the culture and the presence of ascorbic acid. Young cultures (passage 26) produce large amounts of collagen in the absence of ascorbic acid, and this collagen is about 50% hydroxylated compared to that produced by young cultures in the presence of ascorbic acid. Ascorbic acid reduces to about one-half the amount of collagen produced by these young cultures. The young confluent cultures also depend strongly on ascorbic acid for hydroxylation of proline. The dependence declines rapidly with the age of the culture. The collagen produced by young cultures supplied with ascorbic acid is very similar to the type I collagen produced by normal individuals and has about the same degree of hydroxylation of its prolyl residues. The amount of collagen produced by “older” cultures is unaffected by ascorbic acid, but the degree of hydroxylation is normal only if ascorbic acid is present, and is decreased to about 60 to 70% in the absence of the vitamin. “Senescent” cultures showed little, if any, dependency on ascorbic acid, and the collagen produced, with and without the vitamin, is about 80% hydroxylated. The prolyl hydroxylation system of the WI-38 cells and the various controls on the system are age-dependent.

Mercedes A. Paz

Papers

Cross-linking in collagen and elastin

Specific detection of quinoproteins by redox-cycling staining.

$alpha$-AMINO ALCOHOLS AS PRODUCTS OF A REDUCTIVE SIDE REACTION OF DENATURED COLLAGEN WITH SODIUM BOROHYDRIDE.

Collagen synthesized and modified by aging fibroblasts in culture.

The amplefied detection of free and bound methoxatin (PQQ) with nitroblue tetrazolium redox reactions: Insights into the PQQ-locus