  The structure of proteins is essential for its function. The determination of
protein structures is possible by experimental or predicted by computational
methods, but also a combination of both approaches is possible. Here, first an
overview about experimental structure determination methods with their pros and
cons is given. Then we describe how mass spectrometry is useful for
semi-experimental integrative protein structure determination. We review the
methodology and describe software programs supporting such integrated protein
structure prediction approaches, making use of distance constraints got from
mass spectrometry cross-linking experiments
