(Abbreviated Contents Including Section Headings:) Serine Peptidases. Serine Peptidases and Their Clans. Family S1 of Trypsin (Clan SA). Tissue Kallikrein and Its Relatives. Other Families of Clan SA. Clan SB Containing the Subtilisin Family. Clan SC Containing Peptidases with the Alpha/Beta Hydrolase Fold. Clan SE Containing Serine-Type D-Ala-D-Ala Peptidases. Clan SF Containing Peptidases with a Ser/Lys Catalytic Dyad. Clan SH Containing Herpesvirus Assemblins. Clan TA Containing N-Terminal Nucleophile Peptidases. Other Families of Serine Peptidases. Unsequenced Serine Peptidases. Cysteine Peptidases. Cysteine Peptidases and Their Clans. Clan CA Containing Papain and Its Relatives. Clan CC Containing Viral 'Papain Like' Cysteine Endopeptidases. Clan CB Containing the Nodavirus Coat Protein. Other Families of Aspartic Endopeptidases. Metallopeptidases. Metallopeptidases and Their Clans. Clan MA Containing Thermolysin and Its Relatives. Family M1 of Membrane Alanyl Aminopeptidase. Other Families of Clan MA. Family M3 of Thimet Oligopeptidase. Clan MB Containing 'Metzincins' (Clan MB). Family M10 of Interstitial Collagenase (Clan MB). Family M12 of Astacin (Clan MB). Introduction to the Reprolysins (Family M12). Clan MC Containing the Metallocarboxypeptidases. Clan MD Containing Zinc D-Ala-D-Ala-Carboxypeptidase. Clan ME Containing Pitrilysin and Its Relatives. Clan MF Containing Co-Catalytic Leucyl Amino-Peptidases. Clan MG Containing the Methionyl Aminopeptidase Family. Clan MH Containing Varied Co-Catalytic Metallopeptidases. Other Families of Metallopeptidases. Metallopeptidases of Unknown Sequence. Unclassified Peptidases. Peptidases of Unknown Catalytic Type. Subject Index.