胶原调制磷酸钙矿化成核位点的红外光谱研究

对胶原、胶原 /CaCl2 、胶原 /羟基磷灰石等几种体系的红外光谱进行了比较研究。发现胶原矿化后 ,红外光谱中胶原的酰胺Ⅰ ,Ⅱ ,Ⅲ带的吸收强度显著降低 ,Ⅱ ,Ⅲ带接近消失 ,Ⅰ带发生红移现象。提出胶原中的羧基 (COOH )、羰基 (CO )为胶原矿化的两类成核位点 ,钙盐在成核位点上结晶。脱钙胶原(胶原 /羟基磷灰石经盐酸处理 )的红外光谱与纯胶原相似 ,酰胺Ⅰ ,Ⅱ ,Ⅲ带的吸收强度恢复正常 ,表明 :钙盐对胶原中酰胺基的影响是由于钙盐在该成核位点上结晶而导致的“包裹”作用。根据酰胺 3个吸收带的不同振动方式 ,用“包裹”作用解释了胶原 /钙盐复合物中 ,酰胺Ⅰ与Ⅱ ,Ⅲ带的降低程度不同的原因。分析了胶原 /磷酸钙生物矿化的作用机制。

Study of the Nucleation Sites in Collagen Mineralization

By comparing IR spectra of collagen, collagen/CaCl2 and collagen/calcium phosphate, it was found that intensities of amide I, II and III bands were significantly decreased after mineralization. Band amide I shifted to wards lower wave number. This shift indicated chemical interaction between carboxyl groups and Ca ions formed in the mineralization. The result indicated that there was another nucleation site, i.e. carbonyl structure: see text] on collagen, besides the previous reported nucleation site of carboxyl (-COOH) on collagen. The decrease of amide I peak intensity was mainly due to blockage of C=O stretch. Comparing the IR spectra of demineralized collagen and pure collagen, amide I, II and III peaks intensity and position were almost the same. When the mineral dissolved, amide peaks rebounded, which indicated that the crystals nucleated on these sites enwrapped the groups and blocked the groups vibration. The decreases of peak intensity of amide I, II and III were different due to their different vibration modes. The result confirmed that the carbonyl group was one kind of the nucleation site during collagen mineralization. The relationship between the process of collagen mineralization and variety of amide bonds was also studied.