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- Na vidíte krátký úsek polypeptidového řetězce, na kterém si ukážeme základní vlastnosti primární struktury proteinu. Atomy tvořící hlavní řetězec jsou v cik-cak uspořádání, jak vyplývá geometrie jejich vazebných orbitalů. Postranní řetězce aminokyselin (takzvané R skupiny) vyčnívají to prostoru po stranách hlavního řetězce.
- Podívejme se nyní na mezi dvěma aminokyselinami. Kvůli počtu elektronů ve vazebných orbitalech, peptidová vazba vykazuje některé vlastnosti dvojné vazby, která brání volné rotaci atomů na obou stranách této vazby. To znamená, že šest atomů v označených na modelu, jsou spoutané v planární konformaci. Přesvědčte se o tom na .
- Polypeptide chain backbone consist in a monotonous succession in wich the following sequenze repeats: , , . Minding the restrictions to free rotation in peptide bond, we can visualize the polypeptide chain as a succession of . Each of these rigid flats can freely rotate respect each other.
- Secondary structure.- In most proteins there are two main types of secondary structure.
- .- It is a helical structure with a thread pitch of 0.56 nm. Let's go to a . Now let's . The polypeptide chain backbone is coiled and placed at the center of structure, while amino acid side chains protrude outward from this backbone. Let's for a better understanding. Now, let's back to a . A highlights the helical folding of the backbone. Using again a we recover , now highlighted with a spectral color series. Alfa helix structure becomes stabilized by many . All peptide groups in the chain are involved in these hydrogen bonds. to a better understanding.
- Primary structure specifies secondary structure, i.e., is the amino acid sequence which determines that a polypeptide chain folds resulting a alfa helix or other secondary structure. Let's consider the effects of of either sign and the .
- .- Polypeptide chain is folded in zigzag arrangement. Let's and for a better understanding. Notice that a polypeptide chain can have several linear fragments separated by curvatures called beta turns. Now let's recover and highlight the between different linear sections of the chain. This hydrogen bonds give stability to the structure. Let's look now the polypeptide chain represented by a .
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