21176
Here , we determined the crystal structure of iPSP1 from H . thermophilus in the apo - form and in complex with its substrate l - phosphoserine to find structural units important for its phosphatase activity toward l - phosphoserine .
 Chemical: l - phosphoserine; Chemical: l - phosphoserine
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: l - phosphoserine; Chemical: l - phosphoserine