一般氨基酸在pH 2～10之间溶解度受pH影响不是很大。

见下面文献。

超出这个范围，溶解度就很快变大，因为分子带上多余的电荷，这时溶剂化提供的自由能的降低能更好地抵消晶格能。

所以不一定是加碱不利溶解。

比如赖氨酸，中性很难溶，但是1M氢氧化钠就可以很好溶解。

“The influence of the pH on the solubility of amino acids has also been a topic of study. The results indicate that, although in the range of pH between 2 and 10 there is no significant difference on the solubility [12], outside the isoelectric band, a sharp increase on the solubility is observed [13,14].” http://pubs.***.org/doi/pdf/10.1021/ie0602097 http://www.***.org/publications/pac/2005/pdf/7703x0559.pdf参考文献：http://pubs.***.org/doi/pdf/10.1021/ie0602097。