Mucopolysaccharides as a localized factor of egg-shell stability

Selective enrichment of glycopeptides using ground eggshell materials

The current research of protein glycosylation is focused on develop various functionalized hydrophilic materials that can effectively enrich glycopeptides. However, most of these materials require complex synthesis steps, plenty of chemical reagents, and high cost. In this study, we employed the natural eggshell for glycopeptides enrichment for the first time. Using horseradish peroxidase (HRP) tryptic digest as a standard sample, eggshell exhibited excellent sensitivity (0.05 fmol μL^-1), good selectivity [HRP tryptic digest:bovine serum albumin (BSA) tryptic digest = 1:1000], excellent size-exclusion effect (HRP tryptic digest:BSA protein = 1:10,000), good loading capacity (75 mg g^-1), and recovery (97.6 ± 0.3%). In addition, 153 and 114 glycopeptides were captured by eggshell from the serum tryptic digests of normal humans and diabetic patients, respectively. Benefiting from the singular porous structure and abundant biomass, eggshell performed excellently in the capture and separation of glycopeptides. These results demonstrated the potential of environmentally friendly eggshell in glycosylation proteomics analysis.

Characteristics of glycosaminoglycans in chicken eggshells and the influence of disaccharide composition on eggshell properties

Glycosaminoglycans (GAG) are linear, highly negatively charged polysaccharides that may perform an important role in biomineralization. GAG were isolated from chicken eggshell membranes and calcified shells. Disaccharide compositional analysis was performed using liquid chromatography-mass spectrometry. All 4 groups of GAG - hyaluronan (HA), keratan sulfate (KS), chondroitin sulfate (CS), and heparan sulfate (HS) - were detected in shell membranes and in calcified shells. HA was the most plentiful GAG in shell membranes, and CS was the most abundant in calcified shells. The CS present, in both membranes and calcified shells, consisted primarily of 6S_CS-C, 4S_CS-A, and 0S_CS-0 disaccharides. Neither 4S6S_CS-E nor 2S_CS was detectable in shell components. Small amounts of 2S4S_CS-B were detected in membranes and TriS_CS, and 2S4S_CS-B and 2S6S_CS-D were detected in calcified shells. HS in calcified shells contained all disaccharides except for 2S6S. In shell membranes, HS contained primarily NS and 0S as well as small amounts of TriS, NS2S, NS6S_HS, and 6S, but neither 2S6S nor 2S was detectable. The disaccharide composition of membrane CS, as well as membrane and calcified shell HS, were very similar in all eggshells. In contrast, the composition of calcified shell CS disaccharides was highly variable. In membranes, both HA and KS content showed a correlation with egg shape index. The 4S_CS-A content correlated with eggshell strength, and 0S_CS-0 correlated with eggshell strength and calcified shell thickness. HS content and its disaccharide composition showed no apparent correlation to properties of calcified shells. In calcified shells, only HS 6S correlated with egg shape index. This study suggests that GAG content and disaccharide composition of shell membranes might impact the quality of chicken eggshells.

Sorption on eggshell waste--a review on ultrastructure, biomineralization and other applications

The structure, adsorption behavior and applications of eggshell waste materials have been reviewed. The ultrastructure of eggshell particles has been discussed to understand the pore structure as well as the surface geometry of the materials leading to its multifarious applicability. Besides, the ultrastructure studies give full information regarding the chemical constituents of egghell particles as well as eggshell membranes. The process of biomineralization in living organisms, their consequent effect of controlling the formation of inorganic-organic composites propelling their application in biomimetic designing of advanced composites with optimized novel properties leading to advances in materials design have been discussed. Utilization of eggshell waste materials for the removal of organic dyes and heavy inorganic ions has been reviewed with suitable models for understanding their adsorption quality and capacity. The applications of these materials in various fields of research have been extensively discussed.

Relationship between eggshell strength and keratan sulfate of eggshell membranes

Eggshell strength is an important factor in an effort to minimize eggshell breakage, which is a significant problem in the egg production industry. In the current study, we isolated and quantified the specific glycosaminoglycans (GAGs) from the calcified eggshell and shell membranes, which are related to eggshell strength. Our data suggest that GAGs exist in calcified eggshell may influence morphology of shell but do not affect on increase of shell amount while GAGs of shell membranes are maybe highly associated with shell strength with an increase of shell weight. Shell strength showed a strong correlation with the content of GAGs (r=0.942, p<0.0005) and a weak relationship with uronic acid content (r=0.564, p=0.056) in shell membranes. Monosaccharides in shell membranes were determined by Bio-LC analysis for the identification of any specific GAGs related with shell strength. It indicates that the galactose content as a component of keratan sulfate (KS) has a significant correlation with eggshell strength (r=0.985, p<0.0005). These results suggest that eggshell strength is proportional to the KS content of eggshell membranes with an increase of eggshell weight.

Chemical composition of chicken eggshell and shell membranes

This study was undertaken to determine the occurrence of uronic acid in chicken eggshell membranes and to compare chemical compositions among the inner and outer eggshell membranes and the organic matter of eggshell. We report here for the first time the occurrence of uronic acid in chicken eggshell membranes. Uronic acid concentrations were similar (P > 0.05) between the inner shell membrane and outer shell membrane but approximately fivefold higher (P < 0.05) in the organic matter of eggshell. Sialic acid concentrations were the highest (P < 0.05) in the organic matter of eggshell and higher (P < 0.05) in the inner than in the outer shell membrane. Nitrogen concentrations were the lowest (P < 0.05) in the organic matter of eggshell but relatively constant between the two shell membranes. Amino acid analysis showed that the contents of glycine and alanine were higher (P < 0.05) and those of proline and hydroxyproline were lower (P < 0.05) in the organic matter of eggshell compared to shell membranes.

Extraction of glycosaminoglycans from chicken eggshell

The objectives of this study were to analyze glycosaminoglycan (GAG) and mineral composition in the chicken eggshell. Eggshells were decalcified with acetic acid, and GAG was extracted from the decalcified shell by digestion with papain. The eggshell contained an average of 0.024% of its dry weight as uronic acid, a carbohydrate moiety of GAG. The eggshell GAG consisted of approximately 48% hyaluronic acid and and 52% galactosaminoglycan. In the latter, chondroitin sulfate-dermatan sulfate copolymers were the major galactosaminoglycans with dermatan sulfate disaccharide as a relatively minor component. The inorganic material recovered after decalcification accounted for approximately 140% of dry weight of the eggshell and contained 24.11% calcium, 0.04% phosphorous, and 0.23% magnesium, with an undetectable amount of nitrogen.