In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: This fits with the reduced concentration of p . Ala204Asp / p . Asp70Gly - p . Ala539Thr tetrameric enzyme in the plasma and non - detectable fast moving - bands on electrophoresis gels .
### Output Text:
This fits with the reduced concentration of p . Ala204Asp / p . Asp70Gly - p . Ala539Thr tetrameric enzyme in the plasma and non - detectable fast moving - bands on electrophoresis gels . 