A protein or polypeptide, including an enzyme, may be a ???native??? or ???wild-type???, meaning that it occurs in nature; or it may be a ???mutant???, ???variant??? or ???modified???, meaning that it has been made, altered, derived, or is in some way different or changed from a native protein or from another mutant. [0087] ???Amplification??? of a polynucleotide denotes the use of polymerase chai