Osterman D G, Kaiser E T
J Cell Biochem. 1985;29(2):57-72. doi: 10.1002/jcb.240290202.
To extend our studies on peptides and proteins with amphiphilic secondary structures, a series of peptides designed to form amphiphilic beta-strand structures was designed, synthesized, and characterized by circular dichroism and infrared spectroscopy. Amphiphilic beta-strand conformations may be likely to appear in a variety of surface-active proteins, including apolipoprotein B and fibronectin. In a beta-strand conformation, the synthetic peptides will possess a hydrophobic face composed of valine side chains and a hydrophilic face composed of alternating acidic (glutamic acid) and basic (ornithine or lysine) residues. The peptides studied had a variety of chain lengths (5, 9, and 13 residues), and had the amino groups either free or protected with the trifluoroacetyl group. While the peptides did not possess a high potential for beta-sheet formation based on the Chou Fasman parameters, they possessed significant beta-sheet content, with up to 90% beta-sheet calculated for the 13-residue protected peptide. The driving force for beta-sheet formation is the potential amphiphilicity of this conformation. The beta-strand conformation of the 13-residue deprotected peptide was stable in 50% trifluoroethanol, 6 M guanidine hydrochloride, and octanol. The peptides are strongly self-associating in water, which would reduce the unfavorable contacts of the hydrophobic residues with water. It is clear that small peptides can be designed to form stable beta-strand conformations.
为了拓展我们对具有两亲性二级结构的肽和蛋白质的研究，设计、合成了一系列旨在形成两亲性β-链结构的肽，并通过圆二色光谱和红外光谱对其进行了表征。两亲性β-链构象可能会出现在多种表面活性蛋白中，包括载脂蛋白B和纤连蛋白。在β-链构象中，合成肽将拥有一个由缬氨酸侧链组成的疏水表面和一个由交替的酸性（谷氨酸）和碱性（鸟氨酸或赖氨酸）残基组成的亲水表面。所研究的肽具有多种链长（5、9和13个残基），并且氨基要么是游离的，要么被三氟乙酰基保护。虽然根据周法斯曼参数，这些肽形成β-折叠的潜力不高，但它们具有显著的β-折叠含量，对于13个残基的保护肽，计算得出的β-折叠含量高达90%。β-折叠形成的驱动力是这种构象潜在的两亲性。13个残基的脱保护肽的β-链构象在50%三氟乙醇、6 M盐酸胍和辛醇中是稳定的。这些肽在水中强烈自缔合，这将减少疏水残基与水的不利接触。显然，可以设计小肽来形成稳定的β-链构象。
