The scale-free nature of protein sequence space.

The sequence space of five protein superfamilies was investigated by constructing sequence networks. The nodes represent individual sequences, and two nodes are connected by an edge if the global sequence identity of two sequences exceeds a threshold. The networks were characterized by their degree distribution (number of nodes with a given number of neighbors) and by their fractal network dimension.

Network Analysis of Sequence-Function Relationships and Exploration of Sequence Space of TEM β-Lactamases.

The Lactamase Engineering Database (www.LacED.uni-stuttgart.