β-多肽

β-多肽（ Beta-多肽）是由β-胺基酸聚合而成的多肽。母體β-胺基酸是H₂NCH₂CH₂COOH，但大多數的情況下，取代基取代了一個或多個CH鍵。唯一常見的天然存在的β胺基酸是β-丙胺酸。自然界中一般不存在β-多肽。基於β肽的抗生素有潛力作為防止產生抗生素耐藥性的方法，^[1]1996年由Dieter Seebach ^[1]小組和 Samuel Gellman 小組於發表相關的早期研究。 ^[2]

β-丙胺酸，β胺基酸的一個例子。胺基不是連接到α碳而是連接到β碳，在這種情況下是亞甲基。

合成

存在兩種類型的β-多肽：胺旁邊具有有機殘基(R)的稱為β³-多肽，而在羰基旁邊具有有機殘基(R)的稱為β²-多肽。 ^[3]

β-胺基酸可以通過多種途徑製備，^[4] ^[5]包括通過Arndt-Eistert方法合成。

α、β³ 和 β²-多肽中側鏈的排列

二級結構

因為β-多肽比正常肽的骨架長，所以β-多肽會形成不同的二級結構。 β-胺基酸中α和β位的烷基取代基有利於α-碳和β-碳之間的鍵的左旋構象，同時也會影響結構的熱力學穩定性。

由β-多肽組成的許多類型的螺旋結構有許多報道。這些構象可以通過在溶液中形成的氫鍵環中的原子數進行分類：8-螺旋、10-螺旋、12-螺旋、14-螺旋、^[6]和10、12-螺旋。一般來說，β-肽比α-肽可以形成更穩定的螺旋。 ^[7]

臨床應用潛力

β-肽在體外和體內對蛋白酶解穩定，較天然肽有潛在優勢。 ^[8] β-多肽可以用於模擬天然多肽所衍生的抗生素，它們非常有效但因會被蛋白水解酶降解而難以用作藥物，例如馬蓋寧。 ^[9]

列表

存在8種β結構存在：丙胺酸、亮胺酸、賴胺酸、精胺酸、麩胺酸、麩醯胺酸、苯丙胺酸、酪胺酸的形式。 ^[10]天冬胺酸可以認為同時具有β形式和α形式，儘管β形式存在於微囊藻毒素中。 ^[10]

參考

^ ^1.0 ^1.1 β-Peptides: Synthesis by Arndt-Eistert homologation with concomitant peptide coupling. Structure determination by NMR and CD spectroscopy and by X-ray crystallography. Helical secondary structure of a -hexapeptide in solution and its stability towards pepsin. Helvetica Chimica Acta. June 1996, 79 (4): 913–941. doi:10.1002/hlca.19960790402.
^ β-Peptide Foldamers: Robust Helix Formation in a New Family of -Amino Acid Oligomers. J. Am. Chem. Soc. 1996, 118 (51): 13071–2. doi:10.1021/ja963290l.
^ β-Peptides: a surprise at every turn. Chem. Commun. 1997, (21): 2015–22. doi:10.1039/a704933a.
^ Conformationally constrained β-amino acid derivatives by intramolecular [2 + 2]-photocycloaddition of a tetronic acid amide and subsequent lactone ring opening. J. Org. Chem. November 2005, 70 (24): 9798–808. PMID 16292808. doi:10.1021/jo0515226.
^ Efficient synthesis of a β-peptide combinatorial library with microwave irradiation. J. Am. Chem. Soc. September 2005, 127 (38): 13271–80. PMID 16173757. doi:10.1021/ja052733v.
^ Vasantha, Basavalingappa; George, Gijo; Raghothama, Srinivasarao; Balaram, Padmanabhan. Homooligomeric β3 (R)-valine peptides: Transformation between C14 and C12 helical structures induced by a guest Aib residue. Biopolymers. January 2017, 108 (1): e22935 [2022-02-13]. ISSN 1097-0282. PMID 27539268. doi:10.1002/bip.22935. （原始內容存檔於2022-02-13）.
^ Beta-peptides: twisting and turning. Curr. Med. Chem. October 1999, 6 (10): 905–25. PMID 10519905.
^ Toward a rational design of β-peptide structures. J Comput Chem. January 2006, 27 (1): 20–38. PMID 16247761. doi:10.1002/jcc.20299.
^ Mimicry of host-defense peptides by unnatural oligomers: antimicrobial β-peptides. J. Am. Chem. Soc. 2002, 124 (25): 7324–30. PMID 12071741. doi:10.1021/ja0260871.
^ ^10.0 ^10.1 Enantioselective Synthesis of Beta-Amino Acids Sec 2.2, Eusebio Juaristi, Vadim A. Soloshonok

[:0-1] 1.0 ^1.1 β-Peptides: Synthesis by Arndt-Eistert homologation with concomitant peptide coupling. Structure determination by NMR and CD spectroscopy and by X-ray crystallography. Helical secondary structure of a -hexapeptide in solution and its stability towards pepsin. Helvetica Chimica Acta. June 1996, 79 (4): 913–941. doi:10.1002/hlca.19960790402.

[2] β-Peptide Foldamers: Robust Helix Formation in a New Family of -Amino Acid Oligomers. J. Am. Chem. Soc. 1996, 118 (51): 13071–2. doi:10.1021/ja963290l.

[3] β-Peptides: a surprise at every turn. Chem. Commun. 1997, (21): 2015–22. doi:10.1039/a704933a.

[4] Conformationally constrained β-amino acid derivatives by intramolecular [2 + 2]-photocycloaddition of a tetronic acid amide and subsequent lactone ring opening. J. Org. Chem. November 2005, 70 (24): 9798–808. PMID 16292808. doi:10.1021/jo0515226.

[5] Efficient synthesis of a β-peptide combinatorial library with microwave irradiation. J. Am. Chem. Soc. September 2005, 127 (38): 13271–80. PMID 16173757. doi:10.1021/ja052733v.

[6] Vasantha, Basavalingappa; George, Gijo; Raghothama, Srinivasarao; Balaram, Padmanabhan. Homooligomeric β3 (R)-valine peptides: Transformation between C14 and C12 helical structures induced by a guest Aib residue. Biopolymers. January 2017, 108 (1): e22935 [2022-02-13]. ISSN 1097-0282. PMID 27539268. doi:10.1002/bip.22935. （原始內容存檔於2022-02-13）.

[7] Beta-peptides: twisting and turning. Curr. Med. Chem. October 1999, 6 (10): 905–25. PMID 10519905.

[8] Toward a rational design of β-peptide structures. J Comput Chem. January 2006, 27 (1): 20–38. PMID 16247761. doi:10.1002/jcc.20299.

[9] Mimicry of host-defense peptides by unnatural oligomers: antimicrobial β-peptides. J. Am. Chem. Soc. 2002, 124 (25): 7324–30. PMID 12071741. doi:10.1021/ja0260871.

[esbaa-10] 10.0 ^10.1 Enantioselective Synthesis of Beta-Amino Acids Sec 2.2, Eusebio Juaristi, Vadim A. Soloshonok

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