Infrared absorption spectrum of keratin. I. Spectra of α‐, β‐, and supercontracted keratin
Infrared absorption spectrum of keratin. I. Spectra of α‐, β‐, and supercontracted keratin
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DOI：
10.1002/bip.1966.360040506
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发表时间：
1966-05
期刊：
影响因子：
2.9
通讯作者：
E. Bendit
中科院分区：
文献类型：
--
作者：
E. Bendit
角蛋白红外光谱的一些基本特征得到了证实，并发现了一些新的特征：在3-μ区，α-角蛋白螺旋物质的酰胺A频率在3286 cm-1附近接近预期值，而α-角蛋白结晶相的酰胺A频率在3270 cm-1附近低于以前的报道。非晶相在3300 cm-1或更高附近吸收，这导致α-和β-角蛋白中酰胺A带的低强度成分出现在比高强度成分更高的频率处。在6-μ区域，非晶材料的酰胺II频率低于1525 cm-1。在溴化锂中变性的角蛋白，在洗掉试剂后，似乎具有相当大的螺旋含量，可能与原始蛋白质的螺旋含量一样多。水合作用会引起显著的光谱变化。在6亩;区域，结晶材料的酰胺I带的频率降低，而酰胺II带的频率增加，两者都增加了几个波数;非结晶材料的酰胺II频率也增加了几个波数。在3-μ区域，结晶材料的酰胺A频率没有观察到显著变化，而非结晶材料的频率降低。这些光谱变化被解释为结晶相中水与主链羰基的弱缔合，而在非结晶相中，水分子可能在多肽链之间形成氢键桥。酰胺A带的吸收系数和酰胺A、I和II带的积分吸收强度在所研究的三种形式的角蛋白中没有明显变化。
A number of basic features of the infrared spectrum of keratin have been confirmed and some new features have been found. In the 3‐μ region, the amide A frequency of helical material in α‐keratin at 3286 cm.−1 is close to the expected value, but that of the crystalline phase in α‐keratin, near 3270 cm.−1, is lower than had previously been reported. The noncrystalline phase absorbs in the vicinity of 3300 cm.−1 or above, and this causes the low‐intensity component of the amide A band in both α‐ and β‐keratin to occur at higher frequencies than those of the high‐intensity component. In the 6‐μ region, the amide II frequency of noncrystalline material is below 1525 cm.−1. Keratin denatured in lithium bromide, after washing out the reagent, appears to have a considerable helix content, possibly as much as that of the original protein. Hydration causes significant spectral changes. In the 6‐mu; region, the frequency of the amide I band of crystalline material is lowered, while that of the amide II band is increased, both by a few wavenumbers; the amide II frequency of noncrystaline material is also increased by a few wavenumbers. In the 3‐μ region, no significant change is observed in the amide A frequency of crystalline material, while the frequency of the noncrystaline material is reduced. These spectral changes are interpreted in terms of a weak association of water with main‐chain carbonyl groups in the crystalline phase, while in the noncrystaline phase it is thought likely that water molecules form hydrogen‐bond bridges between polypetide chains. The absorption coefficient of the amide A band and the integrated absorption intensities of the amide A, I, and II bands do not vary appreciably in the three forms of keratin investigated.