(a) (b) A NH> COOH B NH, COOH C NH COOH 电镜观察 B C NH, COOH B NH2 COOH A NH, COOH L Helical region Globular region (stalk) (heads) (d) Cr 活化C的电镜图 Cr CIs Ir Cs Is Ir Is Cs电镜观察活化 C1的电镜图