【填空题】精氨酸的pK1(COOH)值为2.17,pK2值为9.04,pK3值为12.98,其pI(等电点时的pH值)为_________。天冬氨酸的pK1(COOH)值为1.88,pK2(COOH)值为3.65,pK3值为9.60,其pI值为_________