Tyrosine (酪胺酸)

tyrosine (酪胺酸)

tyrosine (酪胺酸) 湯偉晉編寫的英文字典

tyrosine (酪胺酸) 湯偉晉編寫的英文字典

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Tyrosine, an essential amino acid, is also an aromatic amino acid and is derived from phenylalanine by hydroxylation in the para position. （酪胺酸是一種必需胺基酸，同時也是一種芳香族胺基酸，並且是由苯丙胺酸在對位進行羥基化而來的。） While tyrosine is hydrophobic, it is significantly more soluble than is phenylalanine. （雖然酪胺酸具有疏水性，但其溶解度明顯高於苯丙胺酸。） The phenolic hydroxyl of tyrosine is significantly more acidic than are the aliphatic hydroxyls of either serine or threonine, having a pKa of about 9.8 in polypeptides. （酪胺酸的酚羥基顯著比絲胺酸或蘇胺酸的脂肪族羥基更具酸性，在多肽中其 pKa 約為 9.8。） As with all ionizable groups, the precise pKa will depend to a major degree upon the environment within the protein. （與所有可離子化的基團一樣，其確切的 pKa 在很大程度上取決於蛋白質內部的環境。） Tyrosines that are on the surface of a protein will generally have a lower pKa than those that are buried within a protein; ionization yielding the phenolate anion would be exceedingly unstable in the hydrophobic interior of a protein. （位於蛋白質表面的酪胺酸，其 pKa 通常會比埋藏於蛋白質內部的酪胺酸更低；因為離子化產生的酚鹽陰離子在蛋白質的疏水性內部將極不穩定。） Tyrosine absorbs ultraviolet radiation and contributes to the absorbance spectra of proteins. （酪胺酸能夠吸收紫外線，並對蛋白質的吸收光譜有所貢獻。） The absorbance spectrum of tyrosine will be shown later; the extinction of tyrosine is only about 1/5 that of tryptophan at 280 nm, which is the primary contributor to the UV absorbance of proteins depending upon the number of residues of each in the protein. （酪胺酸的吸收光譜將在後續展示；在 280 奈米波長處，酪胺酸的消光度僅為色胺酸的約五分之一，而蛋白質的紫外吸收主要取決於其內部這兩種殘基的數量。） (中文由 ChatGPT 負責翻譯)

資訊來源：

University of Arizona

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