蛋白质结构测定.ppt

紫外与荧光光谱在蛋白质结构研究中的应用
利用分光光度法测定大分子溶液状态下的构象,其原理是利用环境对生物大分子生色基团的微扰而使吸收峰值的位置、强度和带宽发生变化,如利用溶剂、pH、温度、浓度等的微扰,使蛋白分子的酪氨酸的吸收峰发生变化,从而推断这些生色基团在大分子中的位置和状态。
1 紫外差光谱法(UV difference spectrum)
pH difference spectrum
denaturation difference spectrum
disturbance difference spectrum
Tyrosine(酪氨酸)
Role in structure: partially hydrophobic, Tyr prefers to be buried in protein hydrophobic cores. Tyr involved in stacking with other aromatic side-chains.
Role in function: Tyr contains a reactive hydroxyl group, thus making it much more likely to be involved in interactions with nonprotein atoms.
芳环氨基酸的重要性
Role in structure: Being hydrophobic, it prefers to be buried in protein hydrophobic cores. The aromatic side chain can also mean that Tryptophan is involved in stacking interactions with other aromatic side-chains.
Role in function: As it contains a non-carbon atom (nitrogen) in the aromatic ring system, Tryptophan is more reactive than phenylalanine(苯丙氨酸) though it is less reactive than tyrosine. The Tryptophan nitrogens can play a role in binding to non-protein atoms, but such instances are rare.
Tryptophan(色氨酸)
Phenylalanine(苯丙氨酸)
Role in structure: Being hydrophobic, Phenylalanine prefers to be buried in protein hydrophobic cores. The aromatic side chain can also mean that Phenyalanine is involved in stacking interactions with other aromatic side-chains.
Role in function: The Phenylalanine side chain is fairly non-reactive, and is thus rarely directly involved in protein function, though it can play a role in substrate recognition.
In general
In particular, hydrophobic amino acids can be involved in binding/recognition of hydrophobic ligands such as lipids. Aromatic residues can also be involved in interactions with non-protein ligands that themselves contain aromatic groups via stacking interactions.
Also aromatic amino acids mon in antibody variable domains and at the interface of other protein-plexes.
mon role for Tyr (Thr) within intracellular proteins is phosphoryl