8199
However , a third one was discovered by the crystal structure of a bifunctional enzyme 4 - hydroxy - 2 - ketovalerate aldolase / acylating acetaldehyde dehydrogenase ( DmpFG ) from Pseudomonas sp . strain CF600 ( Manjasetty et al . , Proc . Natl . Acad . Sci . USA 100 ( 2003 ) 6992 - 6997 ) .
 Chemical: 4 - hydroxy - 2 - ketovalerate; Chemical: acetaldehyde
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: 4 - hydroxy - 2 - ketovalerate; Chemical: acetaldehyde