1.1.99.20	expression in Escherichia coli for sequencing, gene is located a large plasmid, PEG genes have evolved in a plasmid-mediated manner	
1.1.99.20	gene cloned, sequenced and expressed in Escherichia coli	
1.1.99.20	mutant enzymes are expressed in Escherichia coli BL21(DE3)(pLysS) cells