Is there a database providing information about optimum temperature and inactive temperature of enzymes?
UniProtKB has annotations for biophysical and chemical properties, such as maximal absorption, kinetic parameters, pH dependence, redox potentials and temperature dependence.
http://www.uniprot.org/help/biophysicochemical_properties

Such annotations are currently available for about 6800 reviewed entries: http://www.uniprot.org/uniprot/?query=annotation%3A%28type%3Abiophysicochemical_properties%29&amp;sort=score

More specifically, temperature dependences is annotated in about 2000 entries: http://www.uniprot.org/uniprot/?query=annotation%3A%28type%3A%22temperature+dependence%22%29&amp;sort=score