C-Mannosylation is a relatively rare form of protein glycosylation involving the attachment of an α-mannopyranosyl residue to C-2 of the indole moiety of the amino acid tryptophan. This type of linkage was initially discovered in RNase 2 from human urine but later confirmed to be present in many other important proteins. Based on NMR experiments and extensive molecular dynamics simulations on the hundred microsecond timescale we demonstrate that, for isolated glycopeptides and denatured RNase 2, the C-linked mannopyranosyl residue exists as an ensemble of conformations, among which 1C4 is the most abundant. However, for native RNase 2, molecular dynamics and NMR studies revealed that the mannopyranosyl residue favors a specific conformation, which optimally stabilizes the protein fold through a network of hydrogen bonds and which leads to a significant reduction of the protein dynamics on the microsecond timescale. Our findings contribute to the understanding of the biological role of C-mannosylation.

For gaining insight in the mode of action at the molecular level of glycans in biological systems precise knowledge of the structure of the glycans is indispensable. To obtain this fundamental information well-defined starting material, optimal fractionation methods and adequate identification techniques are essential. In this review, the emphasis is on the application of high resolution 1H NMR spectroscopy to the structure determination of glycans of different origin. The power of 1H NMR spectroscopy is the possibility to determine in a non-destructive way all structural parameters of glycans. This is illustrated for glycans that differ in structural complexity.

A brief review is presented of our studies on the structure of glycoprotein-derived glycans. The emphasis is on the introduction of high-resolution 1H-NMR spectroscopy for the unambiguous determination of primary structures. For this purpose, we developed the structural reporter group concept. Structural reporters are defined as unique markers of structural elements in the NMR spectra. Application of this concept led to the discovery of numerous new structures. Furthermore, a number of structures presented in the literature could be corrected. The results are relevant for insight in the various steps in glycan metabolism in health and disease, for the function and mode of action of glycans in vivo and for the interpretation of structural information obtained through other techniques. The strength of the approach is further shown for several highly complex glycoproteins, carrying very heterogeneous and complicated glycans.

A brief review is presented of our studies on the structure of glycoprotein-derived glycans. The emphasis is on the introduction of high-resolution H-1-NMR spectroscopy for the unambiguous determination of primary structures. For this purpose, we developed the structural reporter group concept. Structural reporters are defined as unique markers of structural elements in the NMR spectra. Application of this concept led to the discovery of numerous new structures. Furthermore, a number of structures presented in the literature could be corrected. The results are relevant for insight in the various steps in glycan metabolism in health and disease, for the function and mode of action of glycans in vivo and for the interpretation of structural information obtained through other techniques. The strength of the approach is further shown for several highly complex glycoproteins, carrying very heterogeneous and complicated glycans.

The glycan symbol nomenclature proposed by Harvey et al. in these pages has relative advantages and disadvantages. The use of symbols to depict glycans originated from Kornfeld in 1978, was systematized in the First Edition of "Essentials of Glycobiology" and updated for the second edition, with input from relevant organizations such as the Consortium for Functional Glycomics. We also note that > 200 illustrations in the second edition have already been published using our nomenclature and are available for download at PubMed.

The past decades have shown great progress in the unravelling the biosynthetic pathways of protein glycosylation. The identity of the living cell and its compartmentalisation, the structure of the acceptor protein and the availability of sugar-donors, are key parameters in this non-template driven process. The carefully regulated process comprises a number of sequential steps carried out by specific enzymes, affording a glycosylation pattern that is on one hand specific for the protein and on the other for the cell-type. The comparative investigations of species and organs, have disclosed the universality of the main pathways, versus steps characteristic for specific proteins and cells. In a route wherein so many enzymes at different levels are involved various defects may occur. In the human this feature may give rise to a class of inborn errors of metabolism, known as Congenital Disorders of Glycosylation (CDG), wherein glycosylation is disturbed. The defects may be located at different levels giving rise to various subclasses of disease. The following short reviews present several of the aspects. As illustrated by Liu and Hirschberg mutations in nucleotide sugar transporters may give rise to global defects in glycosylation. This may lead to diseases as shown for human and bovine cases. Mass spectrometry is today an indispensable tool for the study of structural glycomics and changes therein due to mutations. Wuhrer presents the application of mass spectrometry to study glycosylation changes in CDG and other diseases. Foulquier et al. focus the attention on glycosylation disorders resulting from defects in membrane trafficking. In particular, alterations in vesicleformation and -tethering are discussed. In a report by Flanagan-Steet and Steet the functional role of specific classes of glycans during embryonic development in zebrafish are highlighted. The authors stipulate that fundamental work on zebrafish may provide further clues as to glycosylation disorder related diseases. Lauc et al. show the progress that has been made in high throughput glycomics, genomics and epigenomics. This enabled epidemiological and genome-wide association studies of the glycome, providing a wealth of details that are helpful in analysis of the molecular pathology of glycosylation related diseases. Dolichol plays an essential role in protein N-glycosylation. As shown by Welti defects in dolichol pathways may lead to deficiencies in N-glycosylation and thereby to diseases. Katoh and Tiemeyer discuss the progress in insight in Nand Oglycosylation in Drosophila glycoproteins in relation to vertebrate systems. The results are relevant for a further understanding of pathological features. The progress made in the identification of novel types of CDG by homozygosity mapping and exome sequencing is discussed by Matthijs et al. One of the great challenges in this area is the development of effective therapies. Possible therapeutic approaches toward CDGs are addressed by Thiel and Korner. This collection of short reviews, written on invitation by Thierry Hennet, review data on the biosynthesis of protein glycosylation and on the pathological aspects of defects in these routes. It is evident that still a lot of fundamental work is necessary to gain further insight in the cause of diseases related to aberrant glycosylation.

Proteoglycans and collagen molecules are interacting with each other thereby forming various connective tissues. The sulfation pattern of proteoglycans differs depending on the kind of tissue and/or the degree of maturation. Tissues from Cnidaria are suitable examples for exploration of the effects in relation to the presence and the absence of sulfate groups, when studying characteristic fragments of the long proteoglycan carbohydrate chains in silico. It has been described that a non-sulfated chondroitin appears as a scaffold in early morphogenesis of all nematocyst types in Hydra. On the other hand, sulfated glucosaminoglycans play an important role in various developmental processes of Cnidaria. In order to understand this biological phenomenon on a sub-molecular level we have analysed the structures of sulfated and non-sulfated proteoglycan carbohydrate chains as well as the structure of diverse collagen molecules with computational methods including quantum chemical calculations. The strong interactions between the sulfate groups of the carbohydrates moieties in proteoglycans and positively charged regions of collagen are essential in stabilizing various Cnidaria tissues but could hinder the nematocyst formation and its proper function. The results of our quantum chemical calculations show that the sulfation pattern has a significant effect on the conformation of chondroitin structures under study.

ered the novel bacterial monosaccharide constituent bacillosamine (2,4-diamino-

The Publisher regrets that this article is an accidental duplication of an article that has already been published, doi: 10.1016/j.carres.2010.01.003. The duplicate article has therefore been withdrawn.

a Institut fur Biochemie und Endokrinologie, Fachbereich fur Veterinarmedizin, Justus-Liebig Universitat Giesen, Frankfurter Strase 100, 35392 Giesen, Germany College of Life Sciences, Beijing University, Beijing 100871, China Department of NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands d Zentrale Spektroskopie, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany College of Life Sciences, Hunan Normal University, Changsha 410081, China Centro de Investigaciones Biologicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain Biochemisches Institut, Universitat Kiel, Olshausenstr. 40, D-24098 Kiel, Germany Department of Bio-Organic Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands i Slovak Academy of Sciences, Institute of Experimental Physics, Department of Biophysics, 04001 Kosice, Slovakia j Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig Maximilians University Munich, Veterinarstr. 13, D-80539 Munich, Germany

Aspergillus niger is an ascomycetous fungus that is known to reproduce through asexual spores, only. Interestingly, recent genome analysis of A. niger has revealed the presence of a full complement of functional genes related to sexual reproduction [1]. An example of such genes are the dioxygenase genes which in Aspergillus nidulans, have been shown to be connected to oxylipin production and regulation of both sexual and asexual sporulation [2, 3, 4]. Nevertheless, the presence of sex related genes alone does not confirm sexual sporulation in A. niger.

Cell aggregation in the marine sponge Microciona prolifera is mediated by a multimillion molecular-mass aggregation factor, termed MAF. Earlier investigations revealed that the cell aggregation activity of MAF depends on two functional domains: (i) a Ca2+-independent cell-binding domain and (ii) a Ca2+-dependent proteoglycan self-interaction domain. Structural analysis of involved carbohydrate fragments of the proteoglycan in the self-association established a sulfated disaccharide β-d-GlcpNAc3S-(1→3)-α-l-Fucp and a pyruvated trisaccharide β-d-Galp4,6(R)Pyr-(1→4)-β-d-GlcpNAc-(1→3)-α-l-Fucp. Recent UV, SPR, and TEM studies, using BSA conjugates and gold nanoparticles of the synthetic sulfated disaccharide, clearly demonstrated self-recognition on the disaccharide level in the presence of Ca2+-ions. To determine binding forces of the carbohydrate–carbohydrate interactions for both synthetic MAF oligosaccharides, atomic force microscopy (AFM) studies were carried out. It turned out that, in the presence of Ca2+-ions, the force required to separate the tip and sample coated with a self-assembling monolayer of thiol-spacer-containing β-d-GlcpNAc-(1→3)-α-l-Fucp-(1→O)(CH2)3S(CH2)6S- was found to be quantized in integer multiples of 30 ± 6 pN. No binding was observed between the two monolayers in the absence of Ca2+-ions. Cd2+-ions could partially induce the self-interaction. In contrast, similar AFM experiments with thiol-spacer-containing β-d-Galp4,6(R)Pyr-(1→4)-β-d-GlcpNAc-(1→3)-α-l-Fucp-(1→O)(CH2)3S(CH2)6S- did not show a binding in the presence of Ca2+-ions. Also TEM experiments of gold nanoparticles coated with the pyruvated trisaccharide could not make visible aggregation in the presence of Ca2+-ions. It is suggested that the self-interaction between the sulfated disaccharide fragments is stronger than that between the pyruvated trisaccharide.