PREFACE

The two most abundant organic substances on Earth, cellulose and starch, have been known since antiquity and have been put to many uses, although their chemical identity as polymers of D-glucose were not recognized until the early part of the 20th century. Remarkably, while our detailed knowledge of the structural and functional complexity of a great many carbohydrates in biological systems has burgeoned in recent years, many aspects of these two biopolymers have remained poorly understood. This current Volume 64 of Advances features two complementary chapters: Pérez and Samain (Grenoble) focus on the structure, morphology, and solubilization of cellulose, while Mischnick (Braunschweig) and Momcilovic (Stockholm) examine the chemical mod­ification of cellulose and starch with the powerful newer analytical tools now available.

Fiber X-ray crystallography is the key tool used by the Grenoble group to focus on such organizational levels of cellulose structure as chain conformation, chain polarity, chain association, crystal polarity, and microfibril structure. Sundararajan and Marchessault, in Volume 36 of Advances, reviewed knowledge earlier gleaned by this technique, but long-standing questions have remained concerning the packing of chains in native cellulose in relation to cellulose modified by chemical treatment. Pérez and Samain now offer resolution of many of these questions and also provide a glimpse of promising new applications for cellulose based on the design of materials having unique physicochemical properties.

The chemical derivatization of cellulose and starch at the three available hydroxyl groups is a reaction of inherent high complexity on account of differences in the reactivity of the individual groups, questions of accessibility in heterogeneous sys­tems, and their behavior of the groups under kinetic or thermodynamic conditions. Mischnick and Momcilovic take advantage of advanced spectroscopic and chromato­graphic methods to elevate the classic Spurlin model to a higher level of predictability for understanding the structure–properties relationships in chemically modified cellu­lose and starch. Such interpretations point the way for improving reproducibility and the rational design of products having desired properties. Much of the older work found in the patent literature on starch chemistry, as detailed in by Tomasik and coworkers in Volume 59 of this series, employed a largely empirical approach.

A key driving force behind much current research on carbohydrates has been the potential for applications in medicine and biology, as exemplified in the extensive chapter on neoglycoconjugates by Chabre and Roy in the previous volume (63) of this series. In the current volume, Marradi, Martín-Lomas, and Penadés (San Sebastian), working at the forefront of carbohydrate nanotechnology, detail the preparation and properties of nanoparticles functionalized with carbohydrates, with particular focus on gold glyconanoparticles wherein neoglycoconjugates bearing a thiol functional group

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are clustered around a gold nanoparticle to present a glycocalix surface. These carbohydrate-based nanoparticles have been used as tools in interaction studies with proteins in biological systems. The gold-based approach is further extended to the use of a variety of other materials, enabling access to multifunctional glyconanoparticles having a range of optical, electronic, mechanical, and magnetic properties.

The interaction of simple sugars with amines to initiate the series of transformations termed the Maillard reaction is well known in food chemistry, with its initial reaction to form a glycosylamine being succeeded by the Amadori “rearrangement” to afford a 1-amino-1-deoxy ketose derivative. The Amadori rearrangement reaction between glucose and such biologically significant amines as proteins leads to an N-substituted 1-amino-1-deoxy-D-fructose (fructosamine) structure by the process termed “glyca­tion.” Since the 1980s, fructosamine has witnessed a boom in biomedical research, mainly due to its relevance to pathologies in diabetes, Alzheimer’s disease, and related aging processes. In an extensive survey, Mossine and Mawhinney (Columbia, MO) detail important new knowledge on, and applications of, fructosamine-related mole­cules in basic chemistry, and in the food and health sciences. Again reflecting medical and glycobiological aspects, research development on

vertebrate sialidase biology during the past decade is addressed here by Monti (Brescia) along with coauthors Bonten (Memphis, TN), d’Azzo (Memphis, TN), Bresciani (Brescia), Venerando (Milan), Borsani (Brescia), Schauer (Kiel), and Tettamanti (Milan). Since Schauer’s original chapter on sialic acids in Volume 54 of Advances, there have been many developments in our understanding of the important roles played by sialic acid-containing compounds in numerous physiological pro­cesses, including cell proliferation, apoptosis and differentiation, control of cell adhe­sion, immune surveillance, and clearance of plasma proteins. Within this context, sialidases, the glycohydrolases that remove the terminal sialic acid at the nonreducing end of various glycoconjugates, perform an equally pivotal function. The authors detail the subcellular distribution of these enzymes in mammalian tissues and their particular function, and also highlight the trans-sialidases, enzymes abundant in trypanosomes and expressing pathogenicity in humans.

Finally, this volume pays tribute to the life and work of two recently deceased carbohydrate scientists of note, Roy L. Whistler at the age of almost 98 and, younger by a whole generation, Per J. Garegg at the age of 75.

In a uniquely personal account, Whistler’s student, James BeMiller, traces the threads of his mentor’s long career in industry, government, and academia. Whistler’s complex and ambitious character cast a powerful influence over the many who worked with him on the structure and applications of polysaccharides, where he was able to bridge effectively the academia–industry divide in the practical exploitation of numerous polysaccharides. Over the course of many decades, he was the key mover in the establishment and development of the international carbohydrate meetings, as detailed by Angyal in Volume 61 of Advances. He was also the author and editor of

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several books on polysaccharides and their industrial applications, as well as being a contributor to Advances and a member of its Board of Advisors.

In contrast, Per Garegg left his mark as a superbly talented synthetic carbohydrate chemist leading an enthusiastic and devoted group of coworkers in the construction of remarkably complex oligosaccharide sequences of relevance in medicine and biology. Working in Stockholm with his mentor Bengt Lindberg and later as Lindberg’s successor, his synthetic targets focused on the carbohydrate sequences of bacterial polysaccharides whose structures had been elucidated by the Lindberg group. The tribute here by Oscarson (Dublin) and Larm (Stockholm), together with input from other friends and colleagues, paints a picture of a genial man much admired by his student coworkers, an important contributor to the Advances, and a familiar figure at the major carbohydrate meetings.

DEREK HORTON

Washington, DC July, 2010