Problem 1

1.There are 4 chains : A,B,C,D.

2.The average is 35.41 anstron.

3.These three metal ions are potassiums(K).

4.They are Gly77, Gly79 and Tyr78 in all four chains.

Problem 2

Authors : D.A.Doyle, J.M.Cabral, R.A.Pfuetzner, A.Kuo, J.M.Gilbis, S.L.Cohen,     R.Mackinnon

Reference : The structure of the potassium channel : Molecular Basis of K+ Conduction and Selectivity. Science 280, pp. 69(1998)

          Abstract

Problem 3

    2. Chain A : helices 2,  beta-sheet 2
        Chain B : helices 2, beta-sheet 2

    3. Helix1 : Asn153--Thr179
        Helix2 : Glu209--Leu219

    4.