ABSTRACT
For the past 20 years the study of snake venom metalloproteinases has been a very active area of scientific investigation. This is primarily due to the fact that some of the most toxic components in crotalid venoms, the hemorrhagic toxins, are metalloproteinases. The biochemical characterization and protein sequencing of these toxins led one to believe that these were unique proteins with no homologs existing from non-snake organisms. However, with the recent discovery and characterization of novel proteins on guinea pig sperm, it has become evident that there are similar proteins present in mammals which share many of the structural characteristics of the snake venom metalloproteinases. Now the focus of investigation, on both the snake venom metalloproteinases and the mammalian metalloproteinase homologs, is the biological function of these proteins with regard to novel proteolytic and non-proteolytic activities. The discovery of the mammalian proteins has reinvigorated the snake venom field and the existing knowledge of the snake venom metalloproteinases has accelerated the studies of the mammalian proteins. In this chapter we will review the existing information on one family of metalloproteinases, the reprolysins. This family is comprised of the snake venom metalloproteinases and the mammalian metalloproteinase homologs. Particular attention will be focused on the atrolysins, the metalloproteinases from Crotalus atrox, since they represent one of the most thoroughly characterized groups of snake venom metalloproteinases.
