Isatin hydrolase

Isatin has been used in the determination of the enzymatic activity of ketopantoyl-lactone reductase587"590 and other fungal carbonyl reductases591"594, as it is a substrate of these enzymes that is reduced to a dioxindole in a reaction that can be monitored by colourimetry. Ketopantoyl-lactone reductase, also named as isatin hydrolase, can be used to remove unwanted isatin from the broth of the microbial production of indigo595 596. 

A problem connected with the microbial production of indigo is the formation of a small amount of isatin, which could be partly suppressed by adjusting the 02 concentration [108]. Isatin reacts with indoxyl to give indirubin, which gives the finished denim an undesirable red cast. The introduction of an isatin-de-grading enzyme (isatin hydrolase from P. putida) satisfactorily reduced the level of indirubin [107]. 

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