Martínez del Pozo A, Gasset M, Oñaderra M, Gavilanes J G
Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad Complutense, Madrid, Spain.
Biochim Biophys Acta. 1988 Apr 14;953(3):280-8. doi: 10.1016/0167-4838(88)90036-2.
The antitumor protein alpha-sarcin is a single polypeptide chain produced by the mold Aspergillus giganteus. It inhibits protein synthesis in some tumor cells by inactivating the larger ribosomal subunit. The secondary structure of the molecule has been studied by circular dichroism and predictive methods. The protein contains about 40% of periodic structures, mainly located at both extremes of the polypeptide chain. beta-Turns and aperiodic conformation appear at the central part of the molecule. Two different tyrosine populations have been observed in alpha-sarcin. Attempts to correlate solvent accessibility and particular protein regions have been carried out by using CD in the near-ultraviolet region, fluorescence and absorbance spectroscopies as well as acrylamide quenching and hydropathy profiles. Five different pH-induced conformational transitions are detected. Two of them, at pH 2.5 and 10.2, are denaturing transitions. These results are explained in terms of the structural features of this molecule, and related to its ribonucleolytic activity and ability to cross cell membranes.
抗肿瘤蛋白α-肌动蛋白是由巨大曲霉产生的单条多肽链。它通过使较大的核糖体亚基失活来抑制某些肿瘤细胞中的蛋白质合成。该分子的二级结构已通过圆二色性和预测方法进行了研究。该蛋白质含有约40%的周期性结构，主要位于多肽链的两端。β-转角和非周期性构象出现在分子的中心部分。在α-肌动蛋白中观察到了两种不同的酪氨酸群体。通过使用近紫外区域的圆二色性、荧光和吸收光谱以及丙烯酰胺猝灭和亲水性图谱，尝试将溶剂可及性与特定的蛋白质区域相关联。检测到五种不同的pH诱导的构象转变。其中两种，在pH 2.5和10.2时，是变性转变。这些结果根据该分子的结构特征进行了解释，并与其核糖核酸酶活性和跨细胞膜的能力相关。
