4653
The overexpressed His6 - tagged GrsA derivatives were affinity - purified , and the catalytic properties of the deletion mutants were examined by biochemical studies including ATP - dependent amino acid activation , carboxyl thioester formation , and the ability to racemize the covalently bound phenylalanine from L - to the D - isomer .
 GENE: His6 - tagged GrsA derivatives
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
 Entities: His6 - tagged GrsA derivatives 
Answer:
 GENE: His6 - tagged GrsA derivatives