#  David Wheeler,
#  Department of Cell Biology, Baylor College of Medicine, Houston, Texas:
#  "Weight matrices for sequence similarity scoring."
#  Version 2.0, May 1996.
#  David Wheeler defined the Transition/Transversion Matrix as a penalty
#  matrix; the matrix below is a similarity matrix where
#  similarity = 5 - penalty.
   A  T  C  G
A  5  0  0  4
T  0  5  4  0
C  0  4  5  0
G  4  0  0  5
