蛋白质的二级结构ppt课件
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蛋白质的二级结构 The Secondary Structure of Protein
.
history
蛋白质构象研究的开创人鲍林(Pauling)和科里(Corey)在30年代后 期的研究中提出了一个重要的结论：
即蛋白质肽单位的刚性和共面性。
R1 O
H N Cα C HH
Biblioteka Baidu
R2 O
N Cα C OH HH
.
history
.
history
如图所示。 1、肽单位中碳基碳原子和氮原子之间所成的键(肽键)的键长为 0.32nm。这个键长介于单键C—N(0.149nm)和双键C=N（0.127间， 具有部分双键的性质，是刚性的。 2、相反，α-碳原子与羰基碳原子之间是单键，因此。α-碳原子 与氮原于之间也是一个纯粹的单键， 因此，在刚性的肽单位两侧的这些键具有充分转动自由。围绕这 两个键进行的转动用角φ和ψ来代表。Φ代表绕Cα一C单链的转动； ψ代表绕Cα-N单链的转动。如果每一个氨基酸残基的φ和ψ已知， 多肽主链的构象就完全确定。
His most notable scientific contributions were： the development of sundry physical techniques to study protein structure and function ，especially （氢-氘置换） hydrogen-deuterium exchange， his definitions of protein primary, secondary, tertiary and quaternary structure.
the unstretched protein molecules formed a helix (which he called the
α-form); and
the stretching caused the helix to uncoil, forming an extended state
(which he called the β-form).
在相邻的两个肽单位的构象中，非键合原 子间的接近有无障碍，是否符合标准接触距 离，即能量是否达到最低，也是肽链构象能 否稳定存在的重要立体化学原则。
.
history
Kaj Ulrik Linderstrøm-Lang (November 29, 1896 - May 25, 1959) was a Danish protein scientist, who was the director of the Carlsberg Laboratory （嘉士伯实验室） from 1939 until his death.
.
history
.
history
.
history
二面角（dihedral angle）
肽平面1 围绕 Cα2—N1 单键旋 转，其旋转的角度 用Φ表示；
肽平面2 也可 以围绕 Cα2—C2 单键旋转，其旋转 的角度用Ψ表示。
.
history
多肽链主链骨架的构象是由每个Cα的成
对二面角（Φ，Ψ）所决定的。 ②非键合原子间的最小接触距离
history Linus Pauling, Robert Corey and Herman Branson in 1951 developed the α-helix and the β-strand (Astbury's nomenclature was kept)
Linus Pauling and Robert Corey (A) and Herman Branson (B). Pauling's deep understanding of chemical structure and bonding, his retentive memory for details, and his creative flair were all factors in in the discovery of the α-helix. Robert Corey was a dignified and shy x-ray crystallographer with the knowhow and patience to work out difficult structures, providing Pauling with the fundamental information he needed. Herman Branson was a physicist on leave at the California Institute of Technology, who was directed by Pauling to find all helices consistent with the rules of structural chemistry that he and Corey had determined.
.
history Linus Pauling, Robert Corey and Herman Branson in 1951 developed the α-helix and the β-strand (Astbury's nomenclature was kept)
The wooden helix between Pauling and Corey has a scale of 1 inch per Å, an enlargement of 254,000,000 times. (A) Courtesy of the Archives, California Institute of Technology. (B) Courtesy of the Lincoln Universi.ty of Pennsylvania Archives.
.
history
In the early 1930s, William Astbury showed that there were drastic changes in the X-ray fiber diffraction of moist wool or hair fibers upon significant stretching. The data suggested that the unstretched fibers had a coiled molecular structure with a characteristic repeat of ~5.1 Å (= 0.51 nm).
Astbury initially proposed a kinked-chain structure for the fibers. He later joined other researchers (notably the American chemist Maurice Huggins) in proposing that:
.
history
蛋白质构象研究的开创人鲍林(Pauling)和科里(Corey)在30年代后 期的研究中提出了一个重要的结论：
即蛋白质肽单位的刚性和共面性。
R1 O
H N Cα C HH
Biblioteka Baidu
R2 O
N Cα C OH HH
.
history
.
history
如图所示。 1、肽单位中碳基碳原子和氮原子之间所成的键(肽键)的键长为 0.32nm。这个键长介于单键C—N(0.149nm)和双键C=N（0.127间， 具有部分双键的性质，是刚性的。 2、相反，α-碳原子与羰基碳原子之间是单键，因此。α-碳原子 与氮原于之间也是一个纯粹的单键， 因此，在刚性的肽单位两侧的这些键具有充分转动自由。围绕这 两个键进行的转动用角φ和ψ来代表。Φ代表绕Cα一C单链的转动； ψ代表绕Cα-N单链的转动。如果每一个氨基酸残基的φ和ψ已知， 多肽主链的构象就完全确定。
His most notable scientific contributions were： the development of sundry physical techniques to study protein structure and function ，especially （氢-氘置换） hydrogen-deuterium exchange， his definitions of protein primary, secondary, tertiary and quaternary structure.
the unstretched protein molecules formed a helix (which he called the
α-form); and
the stretching caused the helix to uncoil, forming an extended state
(which he called the β-form).
在相邻的两个肽单位的构象中，非键合原 子间的接近有无障碍，是否符合标准接触距 离，即能量是否达到最低，也是肽链构象能 否稳定存在的重要立体化学原则。
.
history
Kaj Ulrik Linderstrøm-Lang (November 29, 1896 - May 25, 1959) was a Danish protein scientist, who was the director of the Carlsberg Laboratory （嘉士伯实验室） from 1939 until his death.
.
history
.
history
.
history
二面角（dihedral angle）
肽平面1 围绕 Cα2—N1 单键旋 转，其旋转的角度 用Φ表示；
肽平面2 也可 以围绕 Cα2—C2 单键旋转，其旋转 的角度用Ψ表示。
.
history
多肽链主链骨架的构象是由每个Cα的成
对二面角（Φ，Ψ）所决定的。 ②非键合原子间的最小接触距离
history Linus Pauling, Robert Corey and Herman Branson in 1951 developed the α-helix and the β-strand (Astbury's nomenclature was kept)
Linus Pauling and Robert Corey (A) and Herman Branson (B). Pauling's deep understanding of chemical structure and bonding, his retentive memory for details, and his creative flair were all factors in in the discovery of the α-helix. Robert Corey was a dignified and shy x-ray crystallographer with the knowhow and patience to work out difficult structures, providing Pauling with the fundamental information he needed. Herman Branson was a physicist on leave at the California Institute of Technology, who was directed by Pauling to find all helices consistent with the rules of structural chemistry that he and Corey had determined.
.
history Linus Pauling, Robert Corey and Herman Branson in 1951 developed the α-helix and the β-strand (Astbury's nomenclature was kept)
The wooden helix between Pauling and Corey has a scale of 1 inch per Å, an enlargement of 254,000,000 times. (A) Courtesy of the Archives, California Institute of Technology. (B) Courtesy of the Lincoln Universi.ty of Pennsylvania Archives.
.
history
In the early 1930s, William Astbury showed that there were drastic changes in the X-ray fiber diffraction of moist wool or hair fibers upon significant stretching. The data suggested that the unstretched fibers had a coiled molecular structure with a characteristic repeat of ~5.1 Å (= 0.51 nm).
Astbury initially proposed a kinked-chain structure for the fibers. He later joined other researchers (notably the American chemist Maurice Huggins) in proposing that: