The systematics of the binding energies of stretched proton-neutron co
nfigurations (f7/2, g9/2)8-, (P3/2, g9/2)6-, (g9/2, p3/2)6- and (g9/2)
9+(2) are studied over a wide range of fp-shell nuclei. The effective
proton-neutron interaction energies deduced from the data are nearly c
onstant for (P3/2, g9/2)6- and g9/2)9+(2) states while the (f7/2,g9/2)
8- configuration reveals an additional repulsive term proportional to
the partial filling of the f7/2 orbit in the target ground state. Two-
body matrix elements are extracted. A crude shell model, which predict
s that the ''citation energy of a stretched state is equal to the sum
of the single-particle energies, works well for the 6- and 9+ states,
but fails for the 8- levels due to neglect of the additional interacti
ons described above. The physics underlying the empirically introduced
basic assumptions of the crude shell model is discussed. The binding
energies are found to be linearly dependent on the mass number A and t
he isospin T(z) component and are well described by the weak-coupling
model of Bansal and French. The derived parameters agree with averaged
values of a similar analysis for the single-particle states in the co
rresponding odd-even neighbours. The data indicate a significant chang
e of the particle-hole energies with closure of the proton f7/2 shell.