EX-4.1 3 a04-11458_1ex4d1.htm EX-4.1 Execution Copy UNIT PURCHASE AGREEMENT by and among MARKWEST ENERGY PARTNERS, L.P., MARKWEST ENERGY GP, L.L.C. KAYNE ANDERSON ENERGY FUND II, L.P., KAYNE ANDERSON CAPITAL INCOME PARTNERS (QP), L.P., KAYNE ANDERSON...