Reducible Collagen Cross-links Research Articles

The chemistry of the collagen cross-links. The mechanism of stabilization of the reducible intermediate cross-links.

The periodate-degradation technique was used to demonstrate the mechanism by which the reducible cross-links of collagen are stabilized. In all the tissues examined, Smith degradations of the 3H-labelled cross-links indicated that dihydroxylysinonorleucine is derived solely from hydroxylysino-5-oxonorleucine, the Amadori-rearranged product of the original condensation reaction. Monohydroxylysinonorleucine exists in both keto and aldimine forms, the former being derived from hydroxyallysine and the latter from allysine. Their relative proportions are tissue-dependent and are related to the degree of hydroxylation of the specific lysine residues in both the telopeptides and the triple helix.

The composition of the insoluble collagenous matrix of bovine predentine.

Predentine obtained from bovine teeth by microdissection was extracted with EDTA and tris-NaCl solutions. The insoluble residue consisted mainly of collagen and resembled dentine collagen in overall amino acid composition. The residue differed in containing no detectable phosphoprotein, a much larger amount of collagen hexose and more non-collagenous glycoprotein, the neutral sugar composition of which was determined. Differences were also observed in the contents of reducible collagen cross-links. Half of the total phosphorus found in the predentine could not be accounted for solely by hydroxyapatite. The remainder was partly soluble and dialysable.

Release of reducible crosslinks of collagen by total enzymic hydrolysis

Enzymic hydrolysis of cow skin insoluble collagen was done to determine if previously identified reducible Schiff base crosslinks were artifacts of the hydrolytic conditions used. Cow skin insoluble collagen was reduced with NaB 3H 4, and samples were subjected to acidic, alkaline and enzymic hydrolysis. In addition, portions of the enzymic hydrolysate were subjected to a second hydrolysis using acid or alkali. The radioactive elution profiles were studied for changes in the concentrations of known crosslink compounds. The results of these experiments show that enzymic hydrolysis does not appear to release the crosslinkages completely, although all of the major ones are found to be present. Alkaline hydrolysis was done on samples of aldol histidine and histidinohydroxymerodesmosine which had been isolated from acid hydrolysates. Synthetic hydroxylysinonorleucine was hydrolyzed with varying concentrations of HCl and with 5 M NH 4OH for 24, 48 and 72 h. Alkaline hydrolysis results in 60% destruction of the crosslinks, aldol histidine and histidinohydroxymerodesmosine. Synthetic hydroxylysinonorleucine is not affected by acid hydrolysis but it is destroyed in direct proportion to the length of time hydrolyzed in 5 M NH 4OH.

Age-related changes in the reducible crosslinks of human tendon collagen

Age-related changes in the reducible crosslinks of human tendon collagen

Age related changes in the reducible cross-links of collagen

FEBS LettersVolume 16, Issue 2 p. 86-88 Full-length articleFree Access Age related changes in the reducible cross-links of collagen A.J. Bailey, A.J. Bailey Department of Biochemistry and Physiology, Agricultural Research Council, Meat Research Institute, Langford, Bristol, UKSearch for more papers by this authorM.S. Shimokomaki, M.S. Shimokomaki Department of Biochemistry and Physiology, Agricultural Research Council, Meat Research Institute, Langford, Bristol, UKSearch for more papers by this author A.J. Bailey, A.J. Bailey Department of Biochemistry and Physiology, Agricultural Research Council, Meat Research Institute, Langford, Bristol, UKSearch for more papers by this authorM.S. Shimokomaki, M.S. Shimokomaki Department of Biochemistry and Physiology, Agricultural Research Council, Meat Research Institute, Langford, Bristol, UKSearch for more papers by this author First published: August 01, 1971 https://doi.org/10.1016/0014-5793(71)80338-1Citations: 126AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume16, Issue2August 01, 1971Pages 86-88 ReferencesRelatedInformation

Thermal transitions in different mammalian collagen-bearing structures

Differential scanning calorimetry (DSC) has been applied to the study of connective tissue to evaluate denaturation process of collagen. We have applied this technique to the study of the ageing of rat skin. We have tried to correlate the variations of the parameters measured by DSC and the modifications of collagen crosslinks with ageing. The thermograms obtained are composed of one main peak located between two shoulders. The relative size of each peak varies with time: the first peak diminishes regularly from 2 to 20 months whilst, at the same time, the third peak increases; the recovery temperature increases with age (+16°C between 2 and 20 months); the total denaturation enthalpy does not vary; the main value obtained is 5.9 · 10−2 J/mg collagen. On the other hand, the assay of reducible collagen crosslinks in rat skin, over the same age range, shows a decrease of heat-labile aldimine crosslinks (essentially hydroxylysinonorleucine). These results and the study of thermograms obtained with altered rat skin (animals treated with β-aminopropionitrile or skin reduced with NaBH4) allow us to conclude that heat-labile and heat-stable crosslinks account for a collagen thermal stabilization which can explain the delay of denaturation characterized by the third peak of DSC thermograms.