The ubiquity of the linguistic metaphor in molecular biology, and part
icularly in sequence analysis was one of the main topics of the 1991 O
pen Problems in Computational Biology Workshop. This year I consider t
he application of a mechanical analogy to sequence analysis and in par
ticular to protein sequences and structures. The mechanistic metaphor
is easily recognized as one of the fundamental concepts behind experim
ental disciplines such as biochemistry, genetics, and cell biology. It
s application to analysis of protein sequences is most clearly seen in
the application of comparative approaches to associating structure wi
th function.