the free energy of the reactants is greater than that of the products. induced-fit model. A model of enzyme-catalyzed reactions in which the enzyme changes shape when substrates bind to the active site; this change in shape is called an induced fit. lock-and-key model A model of enzyme-catalyzed reactions in which the enzyme is a rigid lock and the substrates are the keys that fit into the lock and then react.
System administrator. For the privileged user account, see Superuser. A system administrator, or sysadmin, is a person who is responsible for the upkeep, configuration, and reliable operation of computer systems; especially multi-user computers, such as servers.
1 A security administrator is a specialist in computer and network security, including the administration of security devices such as firewalls, as well as consulting on general security measures.